Use of Models for Water Resources Management, Planning, and Policy

August 1982

NTIS order #PB83-103655 Library of Congress Catalog Card Number 82-600556

For sale by the Superintendent of Documents, U.S. Government Printing Office, Washington, D.C. 20402 Foreword.

The Nation'. water resource policies, affect many problem. in the ~$tates today-food production, energy, regional economic development, enviro:,"qual ity, and even our international balance of trade. As the country grows, and ~. ,. _"'I water supplies diminish, it becomes increasingly important to manage existing sup~th the greatest possible efficiency. In re~ent years, successfull11anagement andplanniag of water resources has increasingly been based on the results ,of mathematical~~.: ~~; Leaving aside the mystique of computers and ~pl~_ mathe~atics, mltematical models are simply tools used for understaIJ.ding w~~f~8odIc. and ",at~ re_e man agement activities. This part of water resource manaFm.~~ii thou~ not as apparent as dams and reservoirs or pipes and sewers, is a vital cOlripcmetif inIDetltiJ;lg tlriW'l ation' s water resource needs. Sophisticated analysis, through the ute of models, can improve our understanding of water resources and wat~r resource activities, and helpprev~ wasting both water and money. - This assessment of water resource models is therefore 'DOt an assessment Of_'$tical equations or computers, but of the Nation's ability t~ Use models to more e.·' tly and effectively analyze and solve our water resource prob~,m.. :, I •. ~rn-.' .. :", ',.,e ~ a:'~e, ssment :',.,' •.,:. rs not only the usefulness of the technology-the models-but _ability of Feder -,.,.' State water resource agencies to apply these analytic too1a ~~ly ..... ,' " : ':;;~~::;i The capabilities of water resource models vary ~ ~'~to ilalue. In. number of areas, further research and development is needed, but ~n~t am.s, usable", reliable tool. currently exist. However, as often occurs, these ~ba!C'OU.~ the capabilities of Federal, State, and local agencies ,to ~pport and effectively u' ',. To day, model use is increasing the efficiency and lowering'the cost ofwaterresou " :'. age ment, but the potential for further improvementtemains great.~1'~:

This report presents options that focus on ways of improving Federal, State-~-.,nd local use of available technologies to analyze water raOurce problems. Opportunities.~ iden tified for congressional action to improve water retOUcce management capabilitifl\-dtrough selective model use-throughout the Federal Government, within individual Fedlbl agen cies, and among State and local governments. The importance of water resource" to the Nation's well-being, ,and the magnitude ofpotenti~ water resource problems in the com ing decades, makes this technqlogy an important tool for ~suring our ability to provide for the water needs of cu~nfand future generations. ,;,,' I About 40 water resources professionals from Federal andState agencies, universities, and the private sector contributed, to this report~Many more provided useful cp~ments on draft materials. OTA was all9,aided by ~ntativ~8 from 27 Federal agencies and offices, and from all 50 States, w~o providedin(oimation in response to OTA surveys and inquiries regarding model use, as well as by·Fed.eral, ·university, and private sector participants in two series of workshops on modeling issues. OTA expresses sincere appre ciation to all these individuals for helping bring ~~~I amount of collective wisdom to this analysis. It~', :. ;1:, .• ' ., ::'

‘Director

iii Contributors to This Report

David Allee Ronald North Cornell University University of Georgia Mary Anderson Donald O’Connor University of Wisconsin, Madison Manhattan College Neil Armstrong John Peters University of Texas at Austin U.S. Army Corps of Engineers John Bredehoeft Charles ReVelle U.S. Geological Survey John Hopkins University James Chalmers Richard Ribbens Mountain West Research, Inc. Bureau of Reclamation Jared Cohon Donald Robey Johns Hopkins University U.S. Army Corps of Engineers Charles Faust Leonard Shabman GeoTrans, Inc. Virginia Polytechnic Institute A. J. Frederick Daniel Sheer Private consultant Interstate Commission on the Potomac River Basin James Geraghty Soroosh Sorooshian Geraghty & Miller Case Western Reserve University Warren Hall Clair Stalnaker Colorado State University U.S. Fish and Wildlife Service James Heany Roland Steiner University of Florida Johns Hopkins University Wayne Huber James Thomas University of Florida Bureau of Reclamation Richard Hyde Harry Torno Holcomb Research Institute U.S. Environmental Protection Agency L. Douglas James Richard Tucker Utah State University Dames & Moore William Johnson Andrew Waldo U.S. Army Corps of Engineers National Counsel Associates, Inc. William Lane Porter Ward Bureau of Reclamation U.S. Geological Survey Arun Malik Walter Wunderlich Johns Hopkins University Tennessee Valley Authority James Mercer Jeffrey Wright GeoTrans, Inc. Johns Hopkins University

OTA appreciates the assistance of many additional people who contributed to this report: ● Participants in the two OTA water resource modeling workshops. ● Federal agency personnel who responded to the OTA Federal agency survey. ● State agency personnel who responded to the OTA State agency survey, and directors of the State water resources research institutes who suggested appropriate respondents. ● The professional societies that reviewed technical materials, including the American Geophysical Union, the American Society of Civil Engineers, the American Water Resources Association, and the National Water Well Association. OTA Water Resource Models Assessment Staff

John Andelin, Assistant Director, (ITA Science, Information, and Natural Resources Division

Robert W, Niblock, Oceans and Environment Program Manager

Project Staff

Robert M. Friedman, Project Director

Chris Ansell, Research Assistant Stuart Diamond, * Writer/Editor Nancy Ikeda, Policy Analyst

Yacov Y. Haimes, Consultant

Administrative Staff

Kathleen A. Beil Linda G. Wade Jacquelynne R. Mulder

OTA Publishing Staff

John C. Holmes, Publishing Officer

John Bergling Kathie S. Boss Debra M. Datcher Joe Henson

● OTA contract personnel . -.------, + -,.-. .

.--. 1 Contents

I ‘.

Chapter Pqe 1. Summary, Issues, and Options...... * .,.***. . 3 2. Introduction to Water Resource Models ...... * ...***. . 25 i 3. General Issues in Model Development, Use, and Dissemination ...... 47 4. Federal Use and Support of Water Resource Models ...... 67 ...... { ...... 97 5. Use of Models by State Governments/ ...... 6. Modeling and Water Resource Issues ...... ,...... ,. . 119 I . . . . Appendix A. Summary of Findings from OTA Workshops on Water Resource Modem . 165 , -- Zig: B. Sumpary of Model Use by Individual Federal Agencies, ...... ***. . 172 c. Summaries of Related Modeling Studies ...... ’...... 199

D. Additional References to Models and Model~g Sm% ~”” “ “”” ● o .* .,,.*,. . 202 E. Tables of Responses to OTA Survey of State-Level~Model Use...... 216 .

Index ...... ● . “ . * . . 237

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Chapter 1 Summary, Issues, and Options [, , Scope ...... 4...... 3 Introduction ...... -...:., ...... 4 Findings ...... - Issues ...... “ Issue 1. Improving Federal Problem-Solv ng Capabilities , ...... Issue 2. Meeting the N’eeds of the States ..,., ...... ,, Issue 3. Establishing Appropriate Modeling Strategies Within Individual Federal Agencies ...... Issue 4. Providi n,g Potential Users With Information About Existing Models . Issue 5, Federal Support for Model-Related Training ......

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Chapter 1 Summary, Issues, and Options

‘. . ‘, . .’ SCOPE,., -..’ t“ , .— , This assessment is intended as a guide for Con- .The full report includes:., J.. , .

)

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4 ● Use of Mode/s for Water Resources Management, Planning, and Policy

INTRODUCTION

Between 1950 and 1975, the Federal Govern- cost of managing water resources. Although the ment spent over $45 billion to develop, maintain, Federal Government spends approximately $50 and improve the Nation’s water resources; 1 expend- million on water-related mathematical models an- itures have spiralled to even higher levels over the nually, such tools are instrumental in planning past decade. Federal efforts range from construc- billions of dollars of annual water resource in- ting dams to increase the reliability of water supplies, generate hydroelectric power, improve flood control, and provide recreational opportunities; to studies for determining whether flood plain areas are sufficiently safe to permit building activities; to providing wastewater treatment for reducing health and environmental risks due to polluted rivers, streams, and lakes. Decisions affecting water resources are made by the Federal, State, and local governments, and by the private sector. These decisions include designing day-to-day management procedures for operating facilities most efficiently, as well as planning and implementing long-range policies for water resources management and construction. Decisions of the latter kind involve large sums of money, and may affect the availability and quality of water for Photo credit: Environmental Protection Agency many decades to come. As the Nation grows, and excess water resource capacities diminish, it becomes increasingly important to manage existing facilities, improve the efficiency of water use, and make long-range plans in ways that maximize the return on natural, capital, and human resources. Mathematical models are among the most sophisticated tools available for analyzing water resource issues. They can use the capabilities of today’s digital computers to perform and integrate millions of calculations within seconds, in order to understand and project the consequences of alternative management, planning, or policy-level activities. Models only assist in decisionmaking—they provide information that people must interpret in light of existing laws, political and institutional Photo credit: U.S. Depaflment of Agriculture structures, and informed professional and scientific Federal, State, and local governments, and the private judgment. Nonetheless, models can significantly sector, provide billions of dollars to support the construction of dams, reservoirs, and water treatment improve the informational background on which facilities. Mathematical models are becoming decisions are based, and substantially reduce the increasingly important in determining the need for such facilities, and in planning, designing, and operating them. ‘Viessman, et al., 7%e Nation Water Outlook to the Year 2000. The Models can be used to help operate existing structures $45 billion estimate includes expenditures by the Army Corps of such as the McNary Dam on the Columbia River (top), Engineers, the Bureau of Reclamation, the Soil Conservation Serv- as well as to develop and run new facilities like the ice, the Tennessee Valley Authority, and the Environmental Protec- illustrated water purification system in tion Agency’s Construction Grants Program outlays. Duncan, Okla. (bottom) Ch. 7—Summary, Issues, and Options . 5 ——

vestments, and managing hundreds of billions of dollars of existing facilities. The role of models in managing water resources has grown dramatically over the past decade—a period in which water resource management itself has become increasingly important. High rates of economic and population growth in water-short areas of the country, decreased availability of water from major ground water aquifers, and increased public concern for the quality of its drinking water, lakes, and rivers have made it even more necessary to manage water resources carefully. In addition, the issue of who is to manage water resources has gained prominence in the political arena, as ways are sought to increase States’ responsibilities for assuring adequate and safe water supplies. The magnitude of the national investment in water resources calls for systematic use of the best analytic tools available to manage this investment. Over the past 20 years, models and sophisticated data processing systems have been advanced as promising great improvements in water resources management, planning, and policy. Yet many consider that these tools have not yet lived up to earlier expectations. OTA was requested to study the use of models in freshwater resources analysis in order to determine their current capabilities, identify ap- Photo credits; :’ Ted Spiege/, 1982 propriate roles for their use, and suggest options Pipelines to provide new supplies of water for the State for improving modeling efforts and model use. of Arizona (top) and the New York City water tunnel (bottom) demonstrate the magnitude of the Nation’s water resource needs. Reliable forecasts of an area’s water requirements are critical for designing efficient and adequate water transport and distribution systems. Models can be used to estimate future demands for water, and to assist in water system design

FINDINGS

Mathematical models have significantly ex- be performed empirically or without computer panded the Nation’s ability to understand and assistance. Further, models have made it feasible manage its water resources. They are currently to quantitatively compare the likely effects of alter- used to investigate virtually every type of water re- native resource decisions. A few examples of situa- source problem; for small- and large-scale studies tions in which models have been applied will il- and projects; and at all levels of decisionmaking. lustrate their uses: In some cases, models have increased the accuracy of estimates of future events to a level far ● Water in excess of amounts needed by crops beyond “best judgment” decisions. In other areas, is often applied to fields to leach out ac- they have made possible analyses that could not cumulated salts. This results in high water use /

e ● use of MOOE;S tor Water Resowces Management, Planning, and Pollcy . . -. ..- . -- -.

,. and high salt loadings in irr”iga&o~~ flows Additional objectives include maximizing hy- returned [(} streams. New hlexico scientists de- dropower production (by releasing water) and veloped ii , ,[)mP uter r~llake users, and releasing water for to maint~in crop yields and favorable soil stream and downstream lakti users). Mathe- salinities. The model has resulted in annual matical models’,have been used on many of the savings in lifter costs of $.’l~0,000 for the Pecos Natipn’s major river systems to address con- , River bas ;~ in New MexiLJ. In addition, the fi”~ ti~e demands by suggesting optimal lower irri~i~[ion return flows have reduced the arn~nf~’ and timing of reservoir releases. salt input i(~ the Pecos I? ~’.wr by 235,000 tons ,~: ~~ ‘~@@@y investigators developed a per year. ‘:. ~-opt;fitititionmcthdtodesi~asewer e The Clear~ Water Act curi(:ntly requires’~clis~ ~=#!&if~r ~hb Long Island Regional Plan- chargers to Aneet effluent---or ‘end-of-pipe’ ‘— ‘ ~ @tn=~%a~di.: The resulting analysis indicated standards. and, in addition, to discharge no !‘ th~~~~~+wer tietiyork that would meet commu- more of iJ. ) ‘(~llutant tha~-, w~eiving waters+?n ‘“&&&@s edut~-be built and operated for $40 safely C(if : v ~ according u; a fixed receivl~g z rniIIi& @ss’&@;cc@f a design developed by ~ ~~~~~ug~~vcti.~on~ ~n~ytic~ ~ethods. s water qui~ilt~ standard. Models are an @@@ tive means of projecting :1 (e rec~”ivimg W@’ quality lhc.t results from different leveh. bf discharge. and are thus ;~ major aid in deter+ mining WIIA[ levels of discharge are peivnissi- ble unchr ~ ~’eiving vat(’, :~andar~l’ ● For the l~~)~thern Virginia area, 197/ ;vas the driest year since 1950. The Occoquan Reser- voir servinv northern Virqinia was nearly empty, ai-i; ! daily withdr:i’”, JS exc~>~:~t:d daily inflows. I_rsing its extended streamflow prediction moclel, the National Weather Service (NWS) determined that there was a lo-percent risk of reaching emergency reservoir knds-a Mu&i. have the potential to provid&@# , risk deerr~; ~ I unacceptable by local authorities. greater benefits for water resource decisionmak- The model was then used to project that an ing in the future. As models are refined and acceptable 2- to 3-pereent risk of reaching receive wider acceptance, they will be able to in- emergency reservoir le~-els would require re- crease the efficiency of water resource manage- ducing J$ ithdrawals by about 20 percent.3 4 ment ~ eacourage cost-effective decisionmak- ● Reserv(~i~s are usual]> multiple-purpose facil- ing. Such rnodeis can do much to increase the ra- ities, m,. ~ i Y“ UJ whose [J!) it’~t i ~~? ‘I . conk[ or co~n- L imm.lity of regulations and [he standard-setting pete. Rcstrvoir mana~ers need to retain suffi- process, and can generally provide a sound scien- cient wtit(’r to ensure an adequate future sup- tific basis fa water policy. The following examples ply for users, yet must release enough for flood illustrate ~g, potential benefits of’ f’uture expansion i~~ m~~&@~: ~ ‘ control ~Ur~(JSes, M \\’Cll ZM t(-) ensure ZKkqUate -=+ ~ :3 ;: : . low-flow levels to protect aquatic life and minim- ● &.49k ad 1975, the Tennessee Valley ize the cost of pollution control downstream. Au@~, (TVA) spent over $2 billion for

‘Impacts of the L’ni~(rsi~ Water Resear~h Program, Task ~’or~c on Re- ~!&&~tir:es development and manage- search and Education in Water Resources, U.S. Department of the =~~~ovmg rainfall forecasting and reswp Interior, March 1981, p. 9. 3 Vt&$t?kxh.tling can make a very significazit D. C. Curtis andJ. C. Schaake, Jr., ‘‘The Nationat Weather Serv- ice Extended Sttiamflow Technique. ” Conference on Reservoir Sys- contribution to the benefits that accrue from teni Regulation, ASCE, Boulder, ~do., ~{lg. 14-17. 1979. these water development projects. Recent 41). P. Sheer, “Analyzing the Risk of Drought: The Occoquan Ex- perience,’’Journa/ of the A&an Water J4’orks Association, May 1980. szmpacts of t~ university Water Research Progam, OP. cit., P. 4. Ch. l-Summ6vy, Issues, and Options ● 7 I

I stuches on six TVA reservoirs found the potential for a 20-percent improvement in operations and annual savings of $4 million through ~\]{: ;mplenlcntation of a s~stcm of reser~roi’r scheduling models. G .NWS estimated that tht~ installation of a ~?fi~,ooo” ?n{}deling systenl m forecast floods on !Ike Connectictlt River basin would provide a reduction in flood damages exceeding $1.5 million per year.7 Nfcdels assist farmers in scheduling irrigz.ticm.s to optimize water conservation while md-intain- ing crop productivity. In INebraska, improved irrigation scheduling has resulted in 25- to 35-percent savings in water pumped #nd cfwy- 8 ~>’ (. CJsts pCX” year. t; ;1 ,,,i, Water resource models vary greatly i~&& capab~ !ities and limitations arid must be ciirehd+ ly selected and used by knowledgeable pro&- ‘ sionals, Some models are designed for manage- i]~t:iit ~~ithin small watersheds; others are uked in > ~ 7 fl n i ‘ ‘, for la C[W ge~-~~raphic:ll areas. Some are ;if~sigyle~ I [o prm’icie highly accurate rN.@ufic? ~~+ tin-mtes; others will provide only gene@ appt-@c- imations. some models are designed for dtuat~ohs i~ J whit. ~: data arc scarce: other r~mdels require large amounts of data. h some instances, decisionrna.kers - credit: C Ted Spiegel, ?982 need only “ballpark” accurac)’ to make decisions, Agriculture account$ for ovw 80 percent of U.S. water hll! in Orher instances mo(iel accuracy may be ex- use. Critical shortages of water for irrigation in many trcmcly important. A clecisionmaker may rccjuire areas of the country make models for w Iudulir’j irrigation a valuable tool for stretching lhY$fed and :1 differc~nt mod{’] in each case, even tlmugh similiar increasingly expensive supplies. Th6$&~odels kinds of problems are being analyz~d~ determine when plants requip water, and how.,@#fr.they will need; same can estimate reductions !rt c~-$ yields if ifrlgatfcm is delayed or reduced ~ ‘ Since modeling is a rapidly advancing and highly :- specialized field. it is extremely diffi~~:for deci- . ..-. .,.. . sionmakers and managers to stay abre~t of new “. developments, or ev(’n to fully unc$’&tan(l i he capabilities and limitations of the toolh’ they currently employ. Under suc~- circu~start~es; ‘a;c~r? tain amount of model misuse and rqis~~ust is; vir- tllally inevitable. A manager who t~~~. a, gi~~n ~node] to analyz( a si? uation it was n~~, tlf:d~:~ed to address; or who overrelies on” the accuracy”of ——— “’~”. Xl. Wunderlich, ‘‘Plannwl Enhanremerit of Mratcr hlanage- ~•• rnent Methods for the TVA Reservoir System,paper pxesermd at the National Workshop on Reservoir Systems Operation, Amerkan Society for Civil Engineers, Aug. 13-17, 1979. often the method of choice to meet the require- ( ‘H. J. Day and K. K. Lee, ‘ Flood Damage Reduction Potential ments of ledslation. Many current laws regarding ~)! R i~w’r Forecast Servicrs in the Connecticut River Basin, .\lf~ ~ ~ ‘J’echnical Memorandum NWS HYDRO-28, February 197 +, aler resources require antiyucai work normtuly ~,. 1 11 lr . - , . 81mpuct~ of the Uniwmlty Water Rc~earch Program, op. cir. , p. . . 1:’” . - , .-, ”. A Gti Ll us a . . 8 ● Use of Models for Water Resources Management, Planning, and Policy

legislation associated with model use at Federal, Memorandum (Sept. 5, 1979) strongly encourages State, or local levels includes: the use of models for performing wasteload allocations. The memo reads: ● Clean Water Act (Public Law 95-217) —sections 107, 201, 208, 209, 301, 302, 303, The link between wasteload allocations and 307, 311, 314, 316, 404, and 405; stream standards is a mathematical model to pre- ● Safe Drinking Water Act (Public Law 93-523) dict water quality as a function of waste discharges. —sections 1412, 1421, 1422, 1424, 1443, and Such models exist and are integral parts of the 9 1444; methodology. ● Toxic Substances Control Act (Public Law 94- 9’ ‘Funding of W’astc Load Allocations and Water Quality Anatyses 469)—sections 4, 5, and 6; for POTW Decisions, Construction Grants Program Requirements ● Resource Conservation and Recovery Act Memorandum, U.S. Environmental Protection Agcnc), PRNI No. (Public Law 94-580)–sections 1008 and 8006; 79-11, Sept. 5, 1979, “Preliminar) Technical Guidance for W’LA Studies, ” p. 4 ● Endangered Species Act (Public Law 93-205) —section 7; ● Surface Mining Control and Reclamation Act (Public Law 95-87)–sections 506, 510, and 515; ● Soil and Water Resource Conservation Act (Public Law 95-192)–sections 5 and 6; ● Water Resources Planning Act (Public Law 89-80)—section 102; ● Coastal Zone Management Act (Public Law 94-370)—section 305; ● Executive Order No. 11988 (Floodplain Man- agement); ● Flood Control Act of 1936 and Amendments— sections 1, 2, and 3; ● National Flood Insurance Act of 1968—section 73; ● Water Research and Development Act (Public Law 95-467)—section 1360; ● Federal Reclamation Act of 1902 and Amend- ments—43 U.S.C. 421 and 422; ● National Environmental Policy Act (Public Law 91-190)—sections 102 and 103; and ● Atomic Energy Act of 1954—10 CFR 20, 50, 61. In translating legislative requirements into management practices, agencies often recommend procedures that depend on the use of models. The Clean Water Act, for instance, requires States to determine the “total maximum daily loads” for those sources of pollutants that can- Photo credit: r Ted Spiegel, 1982 not meet water quality standards through effluent Models are important tools for determining whether individual point-sources of water pollution will prevent limitations regulations. This requires States to rivers, lakes, and streams from meeting Federal water predict the water quality resulting from a number quality standards. Using models, planners can determine of point-source loadings—a responsibility that im- what levels of discharge would be acceptable before treatment facilities are insta//ed; such information is plicitly requires the use of ‘wasteload allocation’ extremely valuable for designing effective models. EPA’s Waste Load Allocation Guidance treatment strategies Ch. l—Summary, Issues, and Options ● 9

Developing and using models is a complex agencies, and effective joint modeling efforts are undertaking, requiring personnel with highly rare. Agencies generally have little information developed technical capabilities, as well as ade- about models available through or being developed quate budgetary support for computer facilities, by other agencies; consequently, agencies tend to collecting and processing data, and numerous develop new models before taking advantage of pre- additional support services. Such capabilities vious or ongoing modeling efforts of other agen- presently reside primarily within the Federal cies. While independent agency-level development Government, or are secured from the private sec- may produce tools that are more responsive to spe- tor with Federal funding. For fiscal year 1979, cific agency needs, the lack of cooperative develop- direct and indirect Federal expenditures in sup- ment has often resulted in agencies being unable port of model development, dissemination, and to muster the resources to adequately develop and use for water resources are estimated at $40 support needed models. Testing models is a dif- million to $50 million annually. The Army Corps ficult, expensive process and very often a major bar- of Engineers, the U.S. Geological Survey (USGS), rier in the way of model use. OTA found instances and the Environmental Protection Agency (EPA) in which more than one agency had developed sim- are the principal agencies involved in water resource ilar models, none of which were used for lack of modeling activities, and together they account for adequate testing and validation. approximately 70 percent of the funds spent in support of water modeling at the Federal level. These Most Federal agencies have no overall strategy expenditures represent an ongoing investment for the development and use of models; conse- in information that supports and improves ex- quently many legislative requirements and deci- penditures of billions of dollars annually for sionmaker needs for information are not being water resource development and management. met. Due to the newness and technical complexity of the modeling field, levels of communication Federal training and assistance is also important between decisionmakers and modelers are low, in assuring the continuing availability of hydrolo- and little coordination of model development, gists, engineers, and modelers with expertise in dissemination, or use occurs within individual water resource issues. The demand for well-trained Federal agencies. Developers, working either as water resource professionals at Federal, State, and Federal employees or as private contractors, tend local government levels, as well as in the private to have a relatively free hand in creating and using sector, far exceeds the number of individuals who models. While the independence afforded to their graduate annually with relevant skills from Amer- development has facilitated rapid advances in ican colleges and universities. Federal support for design, the lack of accountability has resulted in university-level research and training, through the models that often fail to address decisionmakers’ University Water Research Program of the Depart- needs for information, require impractical ment of the Interior, amounted to about $11 million amounts of data, or are not well enough ex- in fiscal year 1980. In addition, a number of Federal plained to enable others to use them. agencies offer important training opportunities in water resources analysis and modeling for Federal Successful modeling requires adequate re- and non- Federal employees alike. While such train- sources for support services, such as user assisting is often critical for keeping professional employ- ance, as well as for development. Presently, ees abreast of developments in these fields, current model development has outstripped correspond- levels of instruction are clearly insufficient to meet ing support for models. In the past, model devel- the growing needs of Federal, State, and local per- opers have put a premium on developing models, sonnel. while support for models—documentation, valida- Virtually all Federal modeling activities are tion, dissemination, user assistance, and mainte- currently managed on an agency-by-agency ba- nance—has been neglected. Often, resources are sis. Little coordination of model development, focused on development, but are unavailable for dissemination, or use occurs among Federal support activities. The neglect of model support has

,–1 , , . - P 7 - .’ 10 Use of Mode/s for water Resources Management, p/annjng, and po/icy led to a multiplicity of models, most of which are sonnel with modeling skills. Consequently, most underutilized. Many of these models cannot be used States depend primarily on the Federal Govern- by personnel other than the developer, due to lack ment to provide them with suitable models, of documentation, access to the model, and user technical expertise, and training in model use. assistance. Those Federal agencies that have had considerable success in.assisting States have made substantial Federal agencies that have had considerable suc- commitments to providing support services— cess with modeling have devoted substantial atten- USGS runs a cooperative program that currently tion to the problem-solving needs of potential users assists over @Xl&ate and local agencies in develop- and decisionmakers, and to providing adequate ing and applying models, while the Corps of En- support services. These programs generally include gineers c Engineering Center (HEC) a central responsibility for disseminating software widely provides services to State and local govern- and documentation, providing training and techni- ments, an@- them in using HEC-built models. cal assistance, and updating and maintaining models. Lack of @#&nation is a major barrier to State and bed’@% models~personnel are often un- State governments frequently use water aware that models for a given type of analysis resource models, although many wish to use already exist. Additionally, many federally devel- them more extensively than is currently possi- oped models are inappropriate for use at the State ble. OTA’S survey of State water resources pro- level. The specific needs of States are infrequentl fessionals indicates that potential levels of model y co&de@@@’ ?&k+ rn@el devdopment. Many use at the State level are at least twice as high S-8$:;.% :=:= =,; &~t~th~ir ‘analytic and modeling as current use levels. Technical capabilities at the c+ad ‘ : I@%@%l l!i+ e.xpandcd if ,S(ates arf m State level tend to be limited—stalls are small, and a;sume ,a: .+-=”<- &’&l%d& iti-futllre tiatm resource &cj- .~g:., prevailing salary scales prevent many States from ; : hiring and/or retaining adequate numbers of per-

. . ~:-; ,+-7 . .... -r . ., .S . - . ., , ~idm%x~&*~. uwr~ A~uf ~- ,, ; The issues discussed in this section focus on the wi&ff&at\on potential to improve the Federal role in develop- jsting M&&‘‘ and “FMk%al Support for Moda~~ ing, using, and disseminating water resource mod- Rel@#~.~i@,” focus on impro~.ing modeling els. opportunities for increasing the efficiency and cap@M1~Kkt&&.tgh the provision of augmented effectiveness of current model-related efforts and mo@l-~@?t@;#&+ici#. ~ ,,~ , .> -* ..-, +, ., , programs are noted, although the general nature , .<- .., %:. ,. ,, , of the options set forth prohibit development of’ ‘-’~i~~~z Improving Federal specific cost estimates or estimates of the potential ..-.“l%6!@3&&i_Solving -4—’==. %+5 .=. + - -=, Capabilities savings associated with a given option. Each op- -..= ~--=-+ ;:+ . >Z+c:. = k ~ . tion presented for congressional consideration is designed to increase the productivity of the billions of dollars in}’ested annuall} in wat~r resources aiid water resource management. Issues 1 and 3, f’k- , proving Federal Problem-Solving Capabiliti~s,,” and “Establishing Appropriate Modeling Strategies Within Individual Federal Agencies, ” are directed toward making m~re effective use of the approxi- overall strategy for developing, using, dissemi- mately $50 million per year spent by the Federal nating, and maintaining these tools. Models tend Government on water resource modeling; issues 2, to be built on an ad hoc basis, in response to im- 4, and 5, “Meeting the Needs of the States, ” “Pro- mediate problems, rather than as a result of inte- Ch. 1-summary, Issues, and options ● 11 grated planning. In the absence of any comprehen- process for coordinating the Federal R&D agenda sive model development and support strategy, Fed- in water resources. Under the water Research and eral agencies are often unresponsive to State and Development Act of 1978, the Secretary of the In- Federal problem-solving needs, or to congressional terior is presently directed to develop a 5- year water directives expressed in water resources legislation. resources research program, drawing on the expertise and advice of appropriate Federal agencies, the The OTA survey of Federal agencies reveals State water resources research institutes, and other great variation in the use of water resource models. appropriate entities. The program is to indicate Although a particular law may assign similar ana- goals, objectives, priorities, and funding recom- lytic responsibilities to a number of agencies, some mendations to the President and Congress for water agencies will employ the most sophisticated com- resources R&D. That document is intended to serve puter tools available for their analyses, while others as the basis for funding allocations in the budget rely primarily on simpler approaches. In some processes of Congress and the Executive Office of cases, this may be all that is needed; however, in the President. , many instances, implementation of legislative requirements could be improved by more sophisti- While the 1978 act recognizes the need to cated Federal analytic capabilities. While a few strengthen, “The capability for assessment, plan- agencies are extensively involved in developing ning, and policy-formulation , . . at the Federal modeling expertise (e. g., Corps of Engineers and and State level, “ it provides no specific direction USGS) most agency modeling efforts vary greatly to determine what mix of research and problem- from issue to issue, from program to program, and solving capabilities can best meet Federal needs. from decisionmaker to decisionmaker. Moreover, by concentrating primarily on research needs, it misdirects mission agency Most water resource problems, and the Federal priorities toward research per se rather than legislation that deals with them, affect a number toward coordinated development and utilization of Federal agencies. However, each agency is indi- of scientific knowledge and related analytic ca- vidually responsible for developing and funding the pabilities. The research focus of the current act analytic tools it requires. While many models have also reinforces tendencies within individual agen- widespread potential use among a variety of Federal cies to fund projects that reflect the agency’s mis- institutions, it is often impossible for anyone agency sion, rather than priority problems identified by to commit the personnel and financial resources Congress and the Executive Office of the President. necessary to bring them to completion. Develop- ing these tools is expensive and technically com- Options available to Congress include: plex. For example, the problem of collecting enough data to fine-tune models and test their accuracy can inhibit model development by a single agency.Un- Congress could amend the Water Research less clear direction and priority-setting mech- and Developement Act of 1978 to specify the de- anisms are provided by Congress and the Exec- velopment of a multiyear plan emphasizing a utive Office of the President, the best analytic mix of R&D needs, unable analytic tools, and mrvices f~~ mmrring that these tools are tools will not be available throughout the Federal supp:~ , ,0 ~@& ~ w , gers. Government, and many needed models will not ... - be built or supported. At present, minimal Federal oversight exists for the finding of applied research and development (R&D) activities. The mechanisms that rently exist for coordinating water resources ana “- “fins almost entirely on research needs. Neith@t% information required for solving policy problems nor the analytic techniques needed to aid in deci- Over a dozen reports defining Federal water sionmaking are directly addressed in the current resources research needs have been prepared over . 12 ● Use of Models for Water Resources Management, Planning, and policy —.— —-—-——-——

the last 20 years. 10 The latest of these, the National opment Act to specifically address a broader range Research Council review of the draft Five-Year of analytic and problem-solving needs for water Plan specified by the act, lists major water resource resources decisionmaking, and provide a mecha- problems, and further states that: nism (such as an interagency coordinating committee) to carry out the intent of the act. For many of the foregoing problems the basic and applied research has already been accomplished in substantial part, if not entirely. What OPTION l-B: is often lacking, however, is adequate technology Congress could establish an interagency unit transfer . . . Solution of many other problems re- whose responsibilities include developing a mul- quires research and development to advance the tiyear plan for water resource analytical needs state of knowledge. and coordinating the implementation of the plan. The individual agency research plans submitted for use in developing the Five-Year Plan gave high Interagency representation may be necessary for priority to the development of mathematical mod- successful coordination. This unit might be housed els. Similarly, a 1977 report on research needs either within the Office of Science and Technology by the Committee on Water Resources Research Policy or in an interagency water resources policy stated that, “Throughout this ‘catalog of needed organization similar to the Water Resources Coun- research, there is a strong theme that calls for con- cil or its potential successor. The unit might be tinually improving mathematical and physical mod- directed to work closely with the Office of Manage- 1 ment and Budget for budgetary rev iew. eling capability. ‘I

As with previous plans, the latest Five-Year Plan OPTION l-C: proposal has not been as effective as it might have When addressing priority problems through been, due to its emphasis on a research agenda. legislation, Congress could establish specific While models have been acknowledged as impor- mechanisms to provide adequate Federal water tant research tools, little attention has been paid to resource analytic capabilities to meet the intent developing the analytic tools and support capability of the legislation. . needed to meet Federal and non-Federal water re- Congress could explicitly direct Federal agencies source problem-solving responsibilities. Major to provide institutional support for the analytic gains in the effectiveness of Federal modeling ef- capabilities needed to implement legislative goals. forts can be achieved through systematic provision A number of approaches could be used for provid- of such support services as assistance in locating ing these capabilities, including centers of excellence and obtaining usable existing models, testing and at universities, operating units within existing Gov- evaluating models for application to different con- ernment organizations, and agency and interagency ditions and decisionmaking needs, and training and demonstration programs for creating support units. technical assistance in using the models. Examples of such support units as the Fish and Mathematical models are an important compo- Wildlife Service Instream Flow Group are described nent of the water resource analysis needs of Federal in chapter 4. agencies. However, as with other forms of R&D, creating these tools is only the first step in estab- Issue 2: Meeting the Needs lishing needed analytic capabilities. Congress could of the States expand the scope of the Water Research and Devel- Most of the Nation’s major water resource legis- —— lation is based on the concept of a strong State-Fed- ~ ~~[>dela[ Walel //esOU7Ce> A Reolew oj the Propo red Flue- year %yarn Plan, Water Rcsourccs Research Re\iew Cornmlttec, Commission on eral partnership for managing and planning the use National Rcsf)ur( es, National Rescar( h Council: National Academy and protection of the Nation’s water. If States are Press, 1981 to fulfill their responsibilities, and take on an 18 DlrectlonJ In (J ~’ W’alo Research 1978-1982, Committee on Water increasing share of water resource management Resources Research of the Federal Coordinating Council for Science,

Engineering, and Technology (Springfield, Va. : National Technical delegations in the future, it is in the Nation’s Information Ser\ice PB 274278, (Xtohcr 1977), best interest to ensure that the States have ac- Ch. l—Summary, Issues, and Options ● 13 cess to, and are capable of using, the best avail- a 5-year coordinated Federal water resources re- able analytic tools. search program. As outlined in Issue 1, ‘ ‘Improv- ing Federal Problem-Solving Capabilities, such Many States depend heavily on Federal agen- a procedure focuses primarily on water resources cies for assistance in modeling, and rely primarily research, and does not give adequate consideration on models that: 1 ) are widely available, 2) have a to developing and supporting analytic tools for solv- long history of use, and 3) are well supported by ing important water resource problems. In addi- Federal agencies. Most States lack the financial tion, it makes the State water resources research resources and the technical expertise required to institutes the primary liaisons between the States develop models independently. States frequently and Federal water resource planning. The in- share common responsibilities or problems, and can stitutes, many of which were created by Federal take advantage of federally developed models de- legislation and operate primarily through Federal signed for application to a wide variety of natural, funding, are primarily research centers. social, and economic situations. Even for situations where differences among States require substantial- The capacities and functions of the State water ly different models, agencies of the Federal Govern- research institutes vary widely, Some compete ex- ment are important centers of expertise to which tensively for discretionary Federal research funding, States. turn for modeling assistance. while others operate primarily on the small basic allocation provided to all 54 institutions. Some are However, many of the models that Federal actively involved in pursuing solutions to water re- agencies routinely use are inappropriate to assist source problems that affect their States, while the States in fulfilling their water resources others concentrate on scientific problems that may responsibilities. Even when agencies develop have few near-term practical ramifications. models that relate to State concerns, they often have no mandate to assist the States in analyzing their Perhaps most importantly, the institutes have a water resource problems. Consequently, many federally authorized research focus that makes it States find that such models are too complex to use, difficult for them to adequately account for the ap- require more input data than States can afford to plied research and problem-solving needs of State collect, or fail to meet specific State analytical needs. and local water resources agencies. While they play a vitally important role in the long-term develop- Although a few agencies, such as EPA, solicit ment of expertise, the institutes are in a relatively general input from the States through advisory pan- weak position to voice State agency needs to the els or other means, State needs are largely ne- Federal Government. glected in Federal agency modeling processes. If State agencies are to utilize Federal models Two additional pressing needs identified in the to a greater extent, practical mechanisms must OTA survey of State water resource agencies are be devised for providing State input into the discussed in detail under issues 4 and 5: 1) better model development processes within individual access to information about existing models; and Federal agencies. 2) increased training opportunities in model use for State personnel. In addition, for the Federal Government to be effective in assisting States to analyze water resource Options available to Congress include: issues, it must first develop reliable means of obtaining information about State needs. Mechanisms OPTION 2-A: for assuring State input into Federal R&D proc- Congress could direct the States to designate esses, as specified under the Water Research and a lead State agency to assist the Secretary of the Development Act of 1978, are inadequate. The cur- Interior, or other designee, in developing a mul- rent act directs the 54 State (and territorial) water tiyear plan for water resource analysis needs. resources research institutes to develop 5-year re- The Water Research and Development Act di- search program reports in close consultation with rects the State water resources research institutes, appropriate State agencies, and to submit these to in consultation with State agencies, to provide in- the Secretary of the Interior for use in developing put to the Five-Year Plan mandated by the act. If f4 ● use of Mode/s for water Resources Management, planning, and policy the Federal Government is to assist States in meeting water-related responsibilities, it must take into account a wide range of State water resource agency information and analytic needs. Congress could amend the act to allow the States to designate a lead State agency or a water resources research institute to participate in planning a broader multiyear Fed- eral agenda.

OPTION 2-B: Congress could strengthen the States’ own capabilities to undertake sophisticated water* source analysis. As the States’ water resource management responsibilities have increased, so have the States’ requirements for sophisticated water resource analysis. Improving the States’ own analytic capabilities, either through federally sponsored training or by funding the States to develop and use their own analytic tools, could allow States to be less dependent on Federal agencies for analysis. For example, the Clean Water Act (Public Law 95-217) directs the Administrator of EPA to make grants to planning agencies to develop a comprehensive water quality control plan for a river basin. Congress might consider, similar programs for water resource development programs. If the States are to assume a greater role in the priority-setting process, Congress might consider including formula funding to strengthen States’ analytic capabilities.

OPTION 2-C: Congress could direct Federal water resource agencies to respond to the analytical needs of the States whenever States are to implement Federal programs.

,.4 - : . For example, under the Safe Drinking Water --- — -- . . - , Act, the States have primary enforcement responsibility for public water systems. The act specifically directs the Administrator of EPA to conduct research and demonstrations of improved methods (i) tO identify and measure the existence contaminants in drinking water (including methods which may be used by State and local health and water officials), and (ii) to identifi the source of such contaminants.” One activity undertaken by EPA— funding the Holcomb Ground Water Model Clear- inghouse—helps the States obtain ground water Many of the major Federal water resource quality models used to identify the transport and agencies lack an intergratedplan for developing fate of pollutants. and supporting models. These agencies general- ,

. Ch. l—Summary, Issues, and Options ● 15 ly develop models in response to an immediate need must be thoroughly explained, or documented, tested to solve particular problems. Few attempts have for use over a wide variety of conditions, easily ac- been made to integrate related modeling efforts cessible, and usable on many different computer within each agency. Moreover, many models are facilities without ma@ modifications. produced without serious attention to decisionmakers’ needs or significant managerial input. To assure that the models are widely and appro- Models may not have been tested to determine their priately used, the sponsoring agency must further ranges of error and applicability to different con- develop a coordinated program of user support ditions, and model assumptions and results may services, including;l) training programs—with not be explained well enough to allow decision- “hands-on” instruction, if possible; 2) one-on-one makers to interpret them properly. Consequently, technical assistance, for problems that arise in the some agencies may have a multiplicity of models, course of running the Model and interpreting its only a few of which are actuaIIy usable. results; and 3) model maintenance, to incorporate improvements and assure that users are informed A few Federal agencies or offices, however, of such modifications: - have established comprehensive strategies for , :,J s developing and supporting models. These strat- Agency expenditures support of such a pro- egies generally take two different forms,: 1) develop= gram need not be large .Services for frequently used ing the capacity to analyze priority water resource models are often provided by the private sector on problems encountered by many users, through a a paid COnsultant basis. Agencies may need only limited number of carefully selected models; or to provide rudimentary services, directing users to 2) developing a general capability for analyzing appropriate sources of further assistance. However, individual problems on a one-time or limited basis. the agency would need to ensure that the necessary Each involves different mixes of model development support is available of the highest quality. and support activities. More general modeling capabilities have been Outstanding examples of both modeling ap- developed by USGS, which maintains a cooperative proaches currently exist within the Federal Govern- assistance program that provides services on a cost- ment. The Hydrologic Engineering Center (HEC) sharing,. to over 600 State and local agencies. has extensively developed the capacity to maintain To meet the requirements of these dispersed users, and support 12 Corps-built models. HEC support USGS maintains numerous models that can be services include training in model use and technical adapted,.by its staff to specific local situations. assistance to users. EPA, upon the completion of its Stormwater Management Model (SWMM), es? USGS model-related activities are described in de- tablished the SWMM Users’ Group to encourage tail in chapter4. of this report. The diversity of user the model’s dissemination and use. Since its incep- need s, particularly for ground water modeling, tion in 1973, membership has grown to over 500 makes this approach particularly helpful for assist- users, who meet to exchange information and ideas ing non-Federal. ., agencies lacking inhouse model- relating to the model's use, assist each other in run- ing capabilities. ning it, and explore alternative analytic tools. A For users with unique information and ana- description of HEC and SWMM User Group ac- lytic needs,developing standard models to an- tivities is provided in chapter 4 of this report, *Jpat.;~:2 ,= ~ needs may be inappropriate. In i S J S Developing selective modeling capabilities can t$@~, J@#%~”$,Jr , strategies emphasizing general bean effective strategy when frequently occur- @~~@#@#~tiesS which stand in readiness ring priority problems appear’ to be solvable ~3@~@!,~~@Wt a model appropriate to each with some kind of standard technique. Models WW#,S,##@+@~ needs , may be more effective, for dealing with these problems are generally Such a strategy requires personel capable of developed in anticipation of repeated application routinely coordinating model development, bring- by a variety of users. Their design must give close ing scientific knowledge and modeling expertise to attention to user needs and capabilities. Models bear on unique situations. While the individual 16 Use of Mode/s for Water Resources Management, planning, and policy —— models require appropriate support (e. g., adequate Two elements that are integral to the develop- testing and documentation), the process focuses on ment of comprehensive modeling strategies—train- the needs of a single decisionmaker or decisionmaking and the availability of information about models ing group, rather than on those of many dispersed —are discussed below as issues 4 and 5. users. Developers must work closely with the user to adapt the model to the particular issue, test and Issue 4: Providing Potential Users apply the model, and interpret its results. With Information About Developing comprehensive strategies for Existing Models building and disseminating water resource models is a pressing need for each of the Federal Many models currently developed by Federal agencies involved in this field. Decisions on what agencies are intended for a single application—once kinds of modeling capabilities to develop, and what they have been built, and are used to analyze a levels of funding to allocate in support of them, need single problem, they are considered to have served to be made at top policymaking levels within each their purpose, and are shelved. Since they are not agency for the agency as a whole, taking into con- designed for distribution, information on their exist- sideration its present and future responsibilities, and ence is not typically made available outside the its role in providing other Federal, State, and local agency. Consequently, other agencies with poten- government entities with assistance in model use. tial uses for these models may be unaware that such While issue 1 addressed strategies for improving models even exist. Often the models are not tested interagency coordination of water resource model- to determine their accuracy and applicability to ing activities, long-range intra-agency planning for other situations, nor are they sufficiently docu- the models and related support services within each mented so that others may choose to use them. agency’s purview must supplement interagency co- Models developed by outside contractors, but which ordination efforts. are left undocumented or are documented inadequately, may not even be usable by other person- An option available to Congress includes: nel within the same agency.

OPTION 3-A: No entity within the Federal Government is Congress could, through its oversight respon- specifically charged with providing information sibilities, direct each of the major Federal water to potential users—Federal or non-Federal— resource agencies to develop a coordinated strat- about the governmentwide availability of water egy for the development, dissemination, and use resource models. Three existing units provide such of models. information as part of a more general mission; each, however, is limited in its ability to gather compre- OTA case studies indicate that coordinated planning is necessary for providing effective institutional hensive information on existing Federal models, support to encourage model development, dissemi- rapidly access that information for users, and match nation, and use. While the approaches used in exist- user needs to available models. ing programs differ widely, successful efforts have The Water Resources Scientific Information two elements in common: 1) the models are of high Center (WRSIC) has supported two major sources quality, have been evaluated over a wide range of of water resource information, Selected Water conditions, and are responsive to users’ needs; and Resources Abstracts, and the Water Resources 2) the models are well documented and maintained, Research in Progress File. Both have provided ref- easily accessible, and are associated with adequate erence services geared to trained water resource technical assistance. Oversight activities to ensure professionals— information on modeling activities the development of a strategy incorporating each is included, but not in a format that allows for ready of these elements could help promote a more effec- access to specific types of models. Moreover, the tive problem-solving capability within Federal agen- services do not reference models or documentation cies. directly. They can at most identify publications in Ch. l—Summary, Issues, and Optjons ● 17 —...— ——— —————————— ———— which models are cited or described, or ongoing resource concerns are the Department of Agricul- research projects that involve modeling activities. ture’s Land and Water Resources and Economic Recent cost-saving initiatives are projected to sub- Modeling System, and the EPA Center for Water stantially curtail WRSIC activities, particularly in Quality Modeling, both of which are described in the area of printed material; however, computer- detail in chapter 4 of this report. based information retrieval services for accessing published work are expected to be maintained. In recent years, the concept of a model clearinghouse has gained many adherents in the scientific The National Technical Information Service and managerial community. Such clearinghouses (NTIS) collects and sells data files, computer pro- would be designed to organize models for easy grams, and model documentation manuals from access by users with specific analytical needs. Federal sources. The sheer magnitude of the NTIS To test the utility of the clearinghouse approach, mission— responsibility for disseminating over 1 EPA has sponsored the development of the Inter- million publications —makes it extremely difficult national Clearinghouse for Ground Water Models for NTIS to provide detailed assistance to poten- (ICGWM) at the Holcomb Research Institute. An tial computer model users. Its information retrieval extensive description of ICGWM is provided in system is not well suited for locating available com- chapter 4 of this report. Preliminary findings indi- puter tapes of models. Recently, NTIS files of com- cate that ICGWM has been very successful in im- puter tapes have been combined with those of the proving the accessibility of ground water models. General Services Administration’s Federal Software Clearinghouses, however, remain a controversial Exchange Center (FSEC). approach. Some water resources professionals are FSEC serves as a central repository for computer skeptical of their cost effectiveness, and of any one programs that Federal agencies consider to be wide- organization’s ability to provide expertise about ly applicable. Its holdings span an extremely wide large numbers of mathematical models. range of subjects, and water resource models com- options available to Congress include: prise only a small portion of the available software. Since FSEC has a very limited staff, it cannot assist users in determining the capabilities and limitations OPTION 4-A: of its models, running them, or interpreting results. Congress could direct the Federal water resource agencies to make information on agen- Moreover, agencies provide models to the Center cy models available to outside users and to es- on a purely voluntary basis, and FSEC regulations tablish mechanisms to distribute these models prohibit the Center from identifying the agency that on request. developed the model to potential users without the agency’s expressed consent. Lacking access to the Several water resource agencies have already es- individuals who developed the model, users may tablished catalogs of existing models, but on the have difficulty in applying it to the problems they whole, it is extremely difficult to obtain informa- need to analyze. The organization’s inability to pro- tion about the existence and specifications of feder- vide user support limits its primary utility to pro- ally developed models. This information is generally fessionals with highly developed modeling expertise. unavailable to potential users in local, State, or All of these organizations provide information other Federal agencies. on models that have been documented and supplied A second component of information transfer is to them by various Federal agencies. However, the dissemination of the computer program for the many Federal models are not entered into any of model. Such programs are also generally difficult these systems, and many that have been entered to obtain. One office with extensive capabilities for have been inadequately documented. distributing models to potential users is HEC, A number of attempts have also been made at described in chapter 4. Congress could direct agen- agency levels to provide relatively detailed infor- cies that do not presently distribute the results of mation on models dealing with specific subject federally funded modeling activities to do so at rea- areas. Two of the larger systems dealing with water sonable cost to the user. 18 ● Use of Models for Water Resources Management, Planning, and policy

OPTION 4-B: “Seed money” would be required to start a na- Congress could expand the role of existing in- tional clearinghouse, but after several years of formation transfer agencies to be more respon- operation, equitably designed user fees could cover sive to the modeling information needs of water a substantial portion of clearinghouse operation managers, and encourage water resource agen- costs. The clearinghouse should provide, at a cies to use these existing mechanisms. minimum, information about available models. Ad- Either FSEC or WRSIC could be expanded to ditional services could include providing computer serve as a Federal Government-wide repository of programs, or more extensive services such as train- water resource models and model information. ing courses. Each of these groups currently provides limited information about water resource models-FSEC fo- OPtion 4-D: cuses directly on models, but has no water resource- Cogress could fund an interagency demon- related mission or expertise, while WRSIC is a stration project to evaluate and compare exist- comprehensive information source for water re- ing models for a representative range of field source research, with no model-related mission or conditions. expertise. Neither provides the support services re- Though thousands of water resource models are quired for assisting potential model users. currently available few have, been evaluated for conditions other than those under which they were Water resource agencies would have to be en- developed. Information about the accuracy of mod- couraged to assist the chosen information transfer ,- els is difficult to obtain-and for many models is agency in expanding its services. nonexistent. Poor validation of models is a major complaint of potential users and a significant con- OPTION 4-C: straint on model use. Congress could establish a national clearinghouse system for the distribution of water resource models. Though several model clearinghouses currently exist in the United States, many important water modeling areas are not covered by any existing organization. The Holcomb Clearinghouse contains an extensive file of ground water models, and EPA’s newly established Center for Water Qual- ity Modeling contains information on a few of the source community professional societies might be most popular surface water quality models. willing to jointly undertake the project. The results of these evaluations, ,,.$ would~ ~;:,: assist professionals in Due to the substantial interconnections and over- choosing tools appropriate to their needs, and give laps among water resource modeling activities, decisionmakers.: greater confidence nce in the results. many professionals consider it desirable to develop . . ., .,.,. .. - , a comprehensive center to which a water resource If the demonstration program is successful, a manager could turn to obtain complete informa- more formal mechanis for interagency model evaluation might be established. tion on the availability of models. Such a center , ::. . . ; . would bring together models developed by the Fed- eral Government, States, and the private sector. A centralized clearinghouse, or a series of clearinghouses, containing information on models of all aspects of water resources—quality and quantity of both ground and surface waters, as well as the social and economic implications of water use— interpret water resource models. However, Feder- could assist water managers to choose amongst the al, State, and private sector personnel reported multitude of available tools. that the inadequacy of current levels of model- .

Ch. 1-Summa#y, Issues, and Options ● 19

related training is a major impediment to meet- training in the use of individual water resource ing the needs of local, State, and Federal agen- models; and 3) continuing education for manager/ cies. State water resource professionals considered decisionmakers and users. Each involves a different increased federally sponsored training opportunities kind of Federal training support. to be a top priority. In addition, officials of Federal Educating water resources professionals in- . agencies that sponsor training programs acknowl- volves extensive academic training edge that inadequate resources are presently pro- and requires support for research and related overhead. Since vided for training nonagency personnel, and that 1965, the Office of Water Research and Technology current agency training opportunities fall far short (OWRT) of the Department of Interior has spon- of demand. If models are to be used effectively in sored the University Water Research Program. The water resource analysis, training in basic concepts program provides seed money, through the State of modeling and in proper interpretation of model water resources research institutes, for training results must be offered to decisionmakers at all lev- students in water-related studies and providing els of government. Finally, ’Federal support for the academic training of future water resource profes- equipment for students and faculty research work. sionals has been threatened by recent cost-saving Individuals who benefit from the program may become m&M developers, or water resources manag- initiatives. ers, or analysts who use water resource models. There are three major aspects to model-related Federal expenditures for the program amounted to training: 1) general educational opportunities in approximately $11 million for fiscal year 1980. water resources research and analysis; 2) specific Funding has been provided on a matching basis (

phOtO credit: Ted Spiegel,1982 A hydrologist at USGS headquarters In Reston, Va., instructs staff in the use of one of the agency’s. streamflow models at a desktop computer terminal 20 ● Use of Models for Water Resources Management, Planning, and policy with State governments, which contributed over Managers and decisionmakers are often unpre- $17 million to the institutes during the same fiscal pared for the problems and complications associated year. Over the past 16 years, the program has made with model use for water resource problems. Many a significant contribution to alleviating the short- have completed their formal education prior to the age of qualifled technical manpower for water re- widespread use of computer modeling techniques, source management. Federal appropriations for the and do not understand the concepts underlying University Water Research Program for fiscal year computer-based simulation and analysis. Few Fed- 1982 have been reduced to approximately $6 mil- eral agencies have yet made a significant com- lion. The fate of the University Water Research mitment to decisionmaker education and re- Program is still uncertain. OWRT has been sched- training to accommodate modeling techniques. uled for elimination, with its responsibilities to be The Instream Flow Group currently conducts an transferred to other offices and programs, before executive training program to enable field person- the end of the current fiscal year. nel and administrators to use model-based recommendations; ICGWM has recently begun a se- Model users require specific training to enable ries of ground water modeling workshops, the most them to use a particular model and apply it to introductory of which discusses the application and actual problems. Such training is a critical com- limitations of models for policymakers and decision- ponent in transferring modeling technologies makers. Nonetheless, Federal efforts to provide con- from the developer to the organizations charged tinuing education in model use for management- with solving water resource problems. Many level personnel are still in very early stages. models go unused, or are underused, because such training is not widely available. USGS and HEC Options available to Congress include: are among the Federal agencies that presently conduct training courses in model use—HEC training courses reserve approximately 10 percent of OPTION 5-A: classroom places for State and non-Corps of Engi- Congress could allocate resources to water neers Federal personnel in 24 weeks of formal train- resource agencies specifically for establishing in- ing programs per year. These courses have great- house and extramural training programs for ly expanded the use of HEC and USGS models, their personnel, and for water managers in State and local agencies. and improved the proficiency of water resource professionals in using them. While both agencies strongly support the concept of one-on-one train- Two types of training programs are needed: ing and “hands-on” workshops in model use, the 1) courses on the use of specific models for poten- cost involved in providing these forms of training tial model users; and 2) continuing education for limit their present use. Using a different approach managers and decisionmakers to understand t: e from that of HEC, the SWMM User’s Group pro- strengths and weaknesses of model-based analyses. vides such assistance informally, or on a fee basis among members. Use of the SWMM model has Several examples of training programs are de- become so widespread that a number of universities scribed in chapter 4. These range from courses of- around the country have begun to provide train- fered by HEC to the informal conferences of ing courses in its use; EPA has not been obliged SWMM’S Model User’s Group. While excellent to provide formal training instruction since the fall examples of training programs exist for agencies of 1976. to follow, the need for additional programs is great. Short training courses in a number of the more A variety of approaches could be used for devel- widely used models are available through public oping adequate training programs. Agencies could and private universities. These courses are highly arrange to fund training provided by universities valuable in providing users with the information with acknowledged expertise in water resource necessary to operate models and interpret their modeling, or develop inhouse training capabilities results. through agency personnel or outside contractors. Ch. l—Summary, Issues, and Options ● 21

OPTION 5-B: Educating students in state-of-the-art analysis Congress could expand the current programs techniques, often available at universities through- assisting university-level water resources edu- out the country but not within Federal, State, and cation. local agencies, brings these techniques to the agen- Training grants to universities, and research cies when these students graduate and are hired. grants that provide the opportunity for students to Research and training programs offered through obtain experience in analyzing water resource prob- the National Science Foundation and OWRT are lems, are two mechanisms by which Congress can important mechanisms for meeting future agency- help provide an adequate supply of well-trained level analytical needs. professionals. ,

Chapter 2 Introduction to Water Resource Models Contents

Page Introduction ...... 25 Introduction to Water Resource Models ...... 26

Water Resource Issues ● ***... ● **.*.** .***...... *...* +...... 30 Case Study of Model Use: Water Resources in Long Island, N.Y...... 40

TABLE

Tab&No. Page 1. Specific Resource Issues Report ...... 26

FIGURES

Fipre No. Page 1. Inadequate Surface Water Supply and Related Problems...... 32 2. Surface Water Pollution Problems From Point Sources ...... 36 3, Surface Water Pollution Problems From Nonpoint Sources ...... 37 4. Ground Water Overdraft and Related Problems ...... 38 Chapter 2 Introduction to Water Resource Models

INTRODUCTION

The Nation’s water resource policies affect many regulations, problems must be analyzed to deter- domestic problems in the United States today— mine an appropriate way to proceed. energy, the environment, food production, regional This part of water resource management, though economic development, and even the international not as apparent as the reservoirs, pipes and sewers, balance of trade. As the country grows, excess water is a vital component in meeting the Nations water supplies diminish, and it becomes increasingly im- resource needs. As the desire for more and cleaner portant to manage existing supplies with the great- water grows, careful analysis becomes more impor- est possible efficiency. Americans are demanding tant. Today, wasting water reduces the amounts more water—and cleaner water—for households, available for others. Over-building dams or sewage industry, agriculture, energy development, recrea- treatment plants wastes money that could be avail- tional use, and aquatic life. For many areas of the able for other purposes. country, the availability of adequate water supplies is a limiting factor in residential construction, Sophisticated analysis, through the use of models, agricultural production, and economic development can improve our understanding of water resources in general. and water resource activities, and help prevent wasting both water and money. As the Nation approaches full utilization of its water resources, water resource management is be- This assessment of water resource models is coming more complex. Different kinds of uses, and therefore not an assessment of mathematical equa- user groups, increasingly compete for limited sup- tions or computers, but of the Nation’s ability to plies. Moreover, interconnections among virtual- use models to more efficiently and effectively ana- ly all aspects of water systems are increasingly lyze and solve water resource problems. The assess- apparent— stream flows affect underground reser- ment considers not only the usefulness of the tech- voirs, for example, while manmade civil works, nology-the models—but the ability of Federal and laws, and relations have profound consequences State water resource agencies to effectively use these for the hydrologic balances of entire regions. analytic tools. Thus, the ability to manage and plan the use of Models have been available to assist water America’s water resources—and determine the con- resources management, planning, and policy for sequences of resource decisionmaking-becomes in- several decades. In 1959, the former Senate Select creasingly important and increasingly difficult as Committee on National Water Resources made one well. In recent years, successful management and of the earliest uses of models for policy purposes. planning has increasingly been based on the results The committee investigated the importance of water of mathematical models. The information provided resources to the national interest, and considered by these tools is used to help make such decisions the Federal activities required to provide the desired as funding flood control structures, planning pollu- quantity and quality of water. To aid in its investi- tion control programs, or operating water supply gations, the committee called on Resources for the reservoirs. Future to develop a model of water supply and projected use for 1980 and 2000.1 Leaving aside the mystique of computers and complex mathematics, mathematical models are During the 1950’s and early 1960’s, many water simply tools used to help understand water re- resource professionals began to realize the poten- sources and water resource management activities. Before the dams and sewage treatment plants are built, before actions are taken to comply with

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26 ● Use of Mode/s for water Resources Management, p/arming, and pO/iCY —

tial of models for improving management and plan- The following section of this chapter outlines the ning—but were overly optimistic about the ease basic principles and functions of water resource with which these tools could be developed and models, and briefly describes the major types and adopted for general use. During the 1970’s, as com- classifications of the models. A further section in- puters became more readily available and the cost troduces the 33 major water resource issues (table of computation decreased, model development 1) for which model use was analyzed and surveyed. flourished. However, as often occurs, the technol- The chapter concludes with a case study that illus- ogy outstripped the capability of the institutions— trates how models were used to deal with a variety the State and Federal agencies—to support it. of water resource problems in the Riverhead-Pecon- Today, model use is increasing the efficiency and ic area of Long Island, N.Y. lowering the cost of water resource management, but the potential for further improvement remains great.

Table I.—Specific Water Resource Issues Addressed in Report .- Surface water flow and supply Ground water—quality and quantity Hydrology: Quantity: Flood forecasting and control Available supplies and safe yields Drought and low-flow river forecasting Conjunctive use of ground and surface waters Streamflow regulation (including reservoirs) Quality: Instream flow needs (fish and wildlife, recreation, hydro- Accidental (and preexisting) contamination of ground electricity, etc. water for drinking water (including toxic substances) Use: Agricultural pollutants to ground water Domestic water supply Movement of pollutants into and through ground waters Irrigated agriculture from waste disposal (landfill siting, injection, etc.) Off stream use (other than domestic and agriculture) Saltwater intrusion Water use efficiency and conservation Economic and sociai Surface water quality Economic: Nonpoint source pollution and land use: Effects of water pricing on use Urban runoff Economic costs of pollution control by industrial sector Erosion and sedimentation Benefit/cost analysis Salinity Regional economic development implications of water Agricultural runoff (other than erosion and salinity) resource policy Airborne pollutants Social and integrative: Water quality (other than nonpoint source and land use): Forecasting water use Wasteload allocation (point source discharges) Social impact analysis Thermal pollution Risk/benefit analysis Toxic materials Competitive water use demands (by region, by sector Drinking water quality and water quality objectives Water quality impacts on aquatic life (including eutrophi- Unified river basin planning and management cation)

SOURCE: Office of Technology Assessment

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INTRODUCTION TO WATER RESOURCE MODELS

What are water resource models? Briefly, they dicting the workings of a water system. Models are are analytical tools used to determine the conse- used to synthesize and analyze the substantial quences of proposed actions or forecast the quan- amounts of water quality, quantity, and societal in- tity or quality of the water in the Nation’s rivers, formation needed for effective planning and man- lakes, or ground waters. These models, which range agement, Effective models condense large amounts in sophistication from simple work with a desk cal- of data, simulate the physical and biological dynam- culator to complex computer programs, are the sci- ics within a water body, or suggest solutions that entific community’s way of understanding and pre- are most equitable to competing water users. Ch. 2—introduction to Water Resource Models ● 27

A model is a ‘‘numerical representation’ of how meaningfuhy quantified, they can be included in the real world or some part of it—a lake, a dam, a mathematical representation, or model, of the or a community—works. More precisely, a model river basin. uses numbers or symbols to represent relationships Models deal with the interrelationships among among the components of these real-world systems. the components of a system. For example, the deci- A river basin, for example, is composed of water sion to store water behind a dam will increase (or flowing in natural (and manmade) channels, and maintain) the size of a lake behind the dam, and may have dams that generate electricity and create decrease the amount of water flowing below the water impoundments. The river’s waters are often dam and the amount of electricity generated at the used by domestic, industrial, and agricultural con- site. The action may increase the number of fish sumers within the basin. The basin normally con- in the lake, attracting more fishing enthusiasts, and tains a wide variety of aquatic and related wildlife, reduce the level of water in a marsh downstream, and may attract numerous users of recreation and inducing birds and other wildlife to migrate else- recreational facilities. All of these may be considered where. Models are simply series of equations that components of a river basin system; if they can be express such relationships in mathematical form.

Photo credit: @ Ted Spiegel, 19S2 In addition to generating hydropower, this dam helps to control streamflow on the lower reaches of the river, and assure adequate water supplies in time of drought. Achieving the multiple objectives involved in reservoir management can be significantly improved and simplified through the use of management-related mathematical models 28 . Use of Models for Water Resources Management, Planning, and policy —

To take the illustration a step further, if a model If a model is found to be a reasonable represen- accurately represents a system, it can be highly use- tation of the real system, it can serve a number of ful in analyzing conflicts among different objectives functions. First, it can be used descriptively to aid for managing that system, or ways in which man- analysts in understanding how the real system agement objectives are complementary. For ensur- works. By way of illustration, when a landfill leaks ing adequate water supplies in times of drought, pollutants into ground water reserves, a model can reservoirs must retain as much water as possible. be used to show how far the contamination has But to control floods, unused storage capacities of spread, and to estimate pollution levels in a given reservoirs must be available to receive excess flows. area. Since these factors can only be measured by Mathematical expressions are used to represent the time-consuming drilling of test wells, the model pro- quantity of flood waters that can be stored when vides the quickest indication of the extent and seri- a given amount of water is being held in reserve ousness of the problem. The insights gained from for water supplies. the model can then be used to determine the probable location of the most contaminated sites, so that A model is necessarily a simplification of the sys- detailed field calculations can be made in those tem it describes. It would not be possible to con- areas. struct a model that accounted for all the minute interactions of a complex system—but perhaps more Models can also be used as Predictive tools. In a important, it would not be useful to do so, either. river, for instance, dissolved oxygen levels depend A model’s value as an analytical tool lies in its abil- to a large degree on levels of bacterial activity, ity to reduce the number of factors to be considered because as organic matter bacterially decomposes, to a manageable size, selecting the most significant the bacteria consume dissolved oxygen. Dissolved interactions in a system, and assuming that other oxygen concentrations also depend on the exchange factors have negligible effects. of oxygen between the river and the atmosphere, Models of how pollutants are transported in a algal photosynthesis and respiration, temperature, river are good examples of the need for simplify- sunlight, and many other interactions. Experiments ing assumptions. In reality, the flow of a river is to determine the direct effects of pollution on dis- three dimensional-the river moves and pollutants solved oxygen levels would require inducing many are dispersed in all directions. It is often prohibitive- different levels of pollution into the river, attempt- ly complex to represent three-dimensional polluting to keep all the other factors constant, and meas- ant transport, however; most river models are de- uring the result. The experiment would be time- signed to describe the transport of pollutants in only consuming, costly, and difficult to control; more- one direction—downstream —and ignore vertical over, it may be highly undesirable to run such an or across-channel flow. For purposes of predicting experiment in the real world. Because equations the concentration of pollutants at a location far that represent the major factors in determining oxy- downstream, i.e., at a drinking water intake pipe, gen levels can be easily manipulated, models can at a specific time, these influences on pollutant predict the direct effects of various pollution levels. transport are negligible. These models can be used to determine what levels of sewage treatment will be necessary for meeting To determine if model assumptions—like those water quality standards before a sewage treatment made for pollutant transport—are valid, model plant is built. results are tested against actual measurements. For example, if the model’s forecast of the time of arriv- Often, however, it is not sufficient to predict the al and the concentration of pollutants at the down- consequences of a single event or series of actions. stream intake pipe is close to the concentration ac- Preventing floods on a river system, for example, tually measured at that time, it would appear that involves opening the floodgates of a dam to a par- it is valid to make these assumptions, at least under ticular position in order to release the greatest possi- these conditions. Usually, in validating a model, as ble amount of water without flooding downstream this process is called, the model is compared with areas. Yet if a river system had 10 floodgates, and actual measurements under a variety of conditions. each floodgate had only 10 positions, a river man- Ch. 2—introduction to Water Resource Models 29 ager would be faced with 10 billion ( 1010) possible otherwise unavailable information incorporate choices (or combinations) of floodgate settings to methodologies that require computer assistance for choose from in the event of a flood. Assuming that their execution. a computer model can predict the amount of water Water resources models can also be characterized that will be released by a particular combination, by the purpose for which they are used. These in- and the impact of the release downstream, in about clude: 1) operations and management; 2) planning; half a minute, evaluating all the possible floodgate 3) policy development; 4) regulation; and 5) data settings would require approximately 10,000 years. management. However, models can also be designed as optimizing tools that use mathematical logic to determine Models for operations and management are used to the best available choice of settings that satisfies the support short-term managerial decisions. These requirements. models might be used to control the operation of The models analyzed in this report address a a sewage treatment plant or to regulate waterflows wide range of water-related issues. These issues can through a system of reservoirs within a river basin. be organized into four broad categories: surface Models that support Planning activities are often water flow and supply, surface water quality, broader in scope than operations and management ground water quality and quantity, and economic models, as they are used as an aid to medium-range and social. decisionmaking. Planning models might be used The category of surface water flow and supply in- to evaluate alternatives for future expansion of a cludes surface hydrology and water use. Hydrology treatment plant or to study the impact of the pro- refers to physical factors that influence the move- posed development of a water-consuming industry ment of water in rivers and streams. Use, in this along a river or stream. case, means water that is withdrawn from a stream Models used for long-range planning would fall for a specific purpose. under the class of policy development models. Policy Surface water quality issues are divided into point models might be used to estimate the effects of sources (e. g., discharges from a factory) and non- energy development on western U.S. water re- point sources (e. g., agricultural runoff). sources. The third category contains issues pertaining to Models for regulation are those used in direct sup- ground water, including available supply and qual- port of enforcement or promulgation of standards ity with respect to intended use. Also included in or in the issuance of permits. For example, a regula- this grouping are factors relating to the possible in- tion model might be used to determine the allowable teractions between ground and surface water re- discharge level for a sewage treatment facility prior sources. to the issuance of a permit for facility expansion. Economic, social, and interrelated factors fall into Some models are developed solely for data manage- the fourth and final category. Included are the eco- ment-organizing and accessing data. These models nomic and/or social factors that might influence, usually are supported by extensive monitoring and either directly or indirectly, the availability, quality, reporting networks, and may include data for a or demand for water resources. wide range of water-related issues. In further categorizing models, it is often useful Yet another method to classify models is by their to distinguish between two major benefits that technical characteristics. Two of the technical cate- models can provide: 1) delivering information more gories most germane to this report are: 1) prescrip- efficiently than was previously possible; and 2) inte- tive v. descriptive models; and 2) deterministic v. grating data to create information that would not probabilistic models. otherwise be available. Models that perform the first function rely on established methodologies (e. g., Descriptive, or simulation, models “describe” how traditional engineering formulae) but use the com- a system operates, and are used to determine puter to speed calculation. Models that produce changes resulting from a specific course of action. 30 . Use of Models for Water Resources Management, Planning, and Policy

They are often used to test alternative plans until in the resulting calculations. The quantitative rela- a satisfactory option is found. tionships among the parts of the system are fixed— results are completely ‘‘determined’ by the model Prescriptive, or optimization, models, on the other and the data provided. hand, “prescribe” a course of action that best meets a specified objective (e. g., least cost or greatest Probabilistic, or stochastic, models produce data water yield). If more than one objective is specified, that are expressed as a range of probable results. these models can be used to describe the tradeoffs Such models take into account the fact that many among best solutions for the various objectives. events appear to occur randomly. For example, the intensity and timing of any particular rainfall event In deterministic models, the results of an event or cannot be precisely predicted, but must be de- series of events are given as a single number or data scribed as a probability of occurrence. series, without indication of extent of possible error

WATER RESOURCE ISSUES

A broad spectrum of activities is involved in land-use activities can aggravate flooding problems. managing water resources. Networks for receiving, In 1975 alone, 107 lives were lost and $3.4 billion routing, and using rainfall—both manmade facil- in property damage resulted from flooding. At the ities and alterations to natural systems—must be same time, $13 billion has been spent on flood man- planned, built, and operated. The quality of various agement and control since 1936.2 water supplies must be analyzed, regulated, and, To a degree, man has learned to manage floods. if necessary, improved through treatment and other Dams have been constructed that can store flood- management practices. Supplies and qualities of waters, releasing them gradually. Stream channels ground water reserves must be determined, and re- have been straightened and dredged to transport sponsible planning provided for their continued use. floodwaters more efficiently. More recently, non- Perhaps most importantly, effective and efficient structural alternatives, including flood forecasting, strategies must be designed for aiding users to get restrictions on building in flood plains, and flood- the greatest possible benefit from the water they proofing, have received attention. Models have consume—in agriculture, residential uses, and in- been widely used to assist in both structural and dustry, as well as for recreational purposes and the nonstructural flood management, including the de- protection of natural environments. sign and operation of dams and other structural Professionals have found modeling useful in vir- controls, the delineation of flood-prone lands, and tually all aspects of these activities. Chapter 6, advanced warnings of floods. “Modeling and Water Resource Issues, ” presents While some areas of the country are plagued with 32 of the 33 specific issue areas in water resource too much water, other regions may be troubled by management listed in table 1, and details the man- a lack of it. Low rates of precipitation, both ner and extent of current model use for each. A regionally and seasonally, can result in both drought broad and more general overview is provided be- and low stream flows. The Water Resources Coun - low, to introduce the reader to the kinds of activities cil has identified 17 out of 106 water resource involved in model-aided water resource analysis and subregions that either have serious water deficien- management. Italicized words or phrases represent cies at present or are projected to have them by the issues specifically analyzed for this report, and ad- year 2000.3 Figure 1 illustrates the regions projected dressed in chapter 6. Perhaps the most striking example of man’s interaction with the hydrologic cycle is flooding. In ‘U. S Water Resources Council, 73e Nation Water Resources 1975-2000, (Washington, D. C.: U.S. Government Printing Office, addition to the natural potential from spring rains, 1978). (Hereafter: WRC, 1978). hurricanes, and the like, urbanization and other ‘Ibid. Ch. Z—Introduction to Water Resource Models . 31

to experience surface water supply and related prob- tives, so that managers can determine an equitable lems through 2000. strategy for operating reservoirs.

Models similar to those used for flood forecasting Conflicting objectives for water are not limited and control can estimate the frequency, timing, and to reservoir operation; intense competition between extent of droughts or low flows. This information instream and offstream uses also exists. Instreamj70w can assist reservoir managers in preparing for po- needs include adequate water for fish and wildlife tential conditions of limited water or in instituting habitat, recreation, navigation, and the generation appropriate conservation measures prior to periods of hydroelectricity. Offjstream uses include irrigated of water shortage. agriculture; domestic water supply; and water for manufacturing, minerals, and energy production. Streamflow regulation is often associated with When water is withdrawn from streams in the tradeoffs among competing objectives. For exam- United States, about two-thirds is returned; the ple, storing reservoir water for droughts may reduce one-third not returned is termed ‘‘consumptive the availability of water for downstream fish and use. Among offstream uses, by far the greatest wildlife habitats. Reservoirs must be operated to consumptive user of water is agriculture. In 1975, meet often-conflicting multiple objectives. Models agriculture accounted for over 80 percent of the can help evaluate the tradeoffs among these objec- total U.S. water consumption. 32 . Use of Models for Water Resources Management, Planning, and Policy

Figure 1 .—Inadequate Surface Water Supply and Related Problems

Explanation Subregion with Inadequate streamflow (1975-2000) Instream use ● 70 percent depleted in average year Fish and wildlife habitat or outdoor recreation 70 percent depleted in dry year t Hydroelectric generation or navigation u Less than 70 percent depleted Boundaries Specific problems as Identified by Federa/ and State/Regkvra/ Study Teams — Water resources region * Conflict between off stream uses “-...”.”... Subregion Inadequate supply of fresh surface water to support— OfLstream use ● Central (municipal) and noncentral (rural) domestic use x Industry or energy resource development A Crop irrigation

SOURCE: U.S. Water Resources Council, The Nation’s Water Resources, 1975-2000, Volume 1: Summary, December 1978.

Total withdrawal of water for offstream use is analyses, resulting in major financial and energy- expected to decline slightly by 2000 due to im- related savings, and alleviating demands on scarce provements in water use efficiency and conservation. ground and surface water reserves. However, while Significant improvements in the efficiency of irriga- withdrawals are expected to decline by 2000, it is tion practices have been made through model-based predicted that the annual consumption of water will Ch. 2—Introduction to Water Resource Models . 33 —— ———.—- ———. — increase by 27 percent over the same period.4 This Runoff and irrigation return flows contribute high increase in consumptive use will aggravate the con- concentrations of fertilizers, pesticides, herbicides, flicts between instream and offstream water uses. sediment, salts, and minerals. Excessive salinity, due to the leaching of salts from the soil by irrigation Decisionmakers at all levels of government are water, may affect receiving waters to the extent that responsible for balancing these competing uses; a they cannot be used for irrigation downstream. wide variety of models is available to assist the deci- Models can be used to help farmers design ‘ ‘best sionmaker with this charge. Models can assist in management practices’ to minimize nonpoint allocating streamflow among conflicting users, and source agricultural pollutants. help forecast future water needs for formulating current policies, long-range planning, and manage- Although erosion, and the resulting sedimentation ment practices. in waterways, are natural processes, human activities— in particular, agriculture—have accelerated Despite the progress made over the last decade, natural rates of soil loss. Sediments from erosion the effects of municipal and industrial point source clog waterways and build up in the slower reaches waste discharges on water quality are still wide- of streams, lakes, and reservoirs. Sediments also spread. About 90 and 65 percent of the Nation’s carry such pollutants as phosphates and pesticides. river basins are affected by municipal and industrial Models are widely used to evaluate land-use man- discharges, respectively. 5 Figure 2 illustrates the agement practices for minimizing soil erosion, as regions of the country exposed to point-source sur- well as to assess the transport and deposition of sedi- face water pollution problems. Models can estimate ments for river management. the ability of streams to assimilate pollutants from these various point sources so as to meet receiving Storm runoff from urban areas—containing oil and water quality standards. Such wasteload allocation grease, lawn fertilizer, garbage, and soil from con- models are extensively relied on for planning struction sites— affects half of the Nations river purposes. basins. Models of urban runoff can be used to simulate the quantity and quality of pollutants from Therma/ additions from electric power generation a particular area and to compare the effectiveness and manufacturing sources elevate stream tempera- of alternative control strategies. tures, and can significantly affect aquatic life if the temperature rise or rate of change is great enough. Airborne pollution is also a source of nonpoint con- Models are routinely employed to estimate the ef- taminants. For example, the combustion of fossil fects of thermal wastes from existing and planned fuels produces sulfur and nitrogen oxides, which facilities. have been linked to the phenomenon of “acid rain. While the ultimate effects of airborne Dispersed nonpoint pollution sources are equally pollutants are not certain, increased rainfall acidi- significant contributors of contaminants to the Na- ty has led to such effects as the loss of fish in sen- tion’s waterways, and are significantly more diffi- sitive lakes. Models that deal with acid rain and cult to analyze and control than point sources. other airborne pollution to water are currently being Figure 3 illustrates the areas of the country exposed developed. to nonpoint pollution problems. An Environmen- tal Protection Agency inventory estimates that Water pollution from both point and nonpoint about one-third of the oxygen-demanding loads, sources can have harmful effects on aquatic life. Exces- two-thirds of the phosphorous, and three-quarters sive concentrations of nutrients can cause explosive of the nitrogen discharged to streams comes from growth of aquatic plants. organic wastes, such as nonpoint agricultural sources. Agricultural runoff, the sewage, can reduce oxygen levels in lakes and most widespread nonpoint source problem, affects streams, adversely affecting fish. Models can be 70 percent of the country’s major river basins.6 used to assist biologists in determining the effects of various pollutants on aquatic life. + 1 bid 11 ‘ .$ L P .4 .!’a[~ona[ JI kt~r Qua[lt) In~ rotor) — 1‘}77 R@Jrt to (,’on - Toxic pollution of drinking water is one of the most <~fj~, f:I’.A-44f)/4-78-f)ol serious water quality problems facing the Nat ion “It)l(~ today. The magnitude of the problem is large— 34 ● Use of Models for Water Resources Management, Planning, and Policy

Photo cred/t: G Ted Spiegel, 1932 Fry at left have been raised with only 20 percent of the normal oxygen level of freshwater. The EPA laboratory in Duluth, Minn., performs experiments like these to determine what conditions are necessary to assure that offspring develop normally, like those on the right. Models that estimate oxygen levels in water bodies, when combined with Iaboratoty data, can be used for estimating effects of actual conditions in rivers, lakes, and streams on aquatic life

30,000 chemicals identified as toxic to humans are ground water, which serves up to 40 percent of the presently produced commercially. Many toxicants population, is frequently consumed untreated from are difficult to detect and remove using present individual wells. Toxicology models, which relate technologies. Extensive potential exists for using concentrations of hazardous substances to human models to trace the transport and fate of toxicants health, are used to aid in setting standards. through the environment, and to test different man- Stored underground in the Nation’s ground agement approaches for preventing toxicants from water reserves is an amount of water equal to 35 reaching water supplies. years of surface water runoff. Nonetheless, ground Other agents of water-borne disease also pose water resources are exhaustible. Aquifers—water- threats to drinking water quality, including bacteria bearing soil or rock— can be overexploited if ground and viruses. Over 4,000 cases of water-related ill- water is removed faster than it can be recharged. nesses are reported each year, primarily from bac- Ground water ‘‘overdraft’ can result in increased terial and viral sources. 7 While surface waters are water pumping costs, declines in streamflow, land extensively treated before distribution to users, subsidence, and saltwater intrusion. Figure 4 illustrates the regions of the country experiencing 7WRC, 1978. significant ground water overdraft. Assessing avail- Ch. Z—Introduction to Water Resource Models 35

Photo credit: C Ted Spiege/, 1982

A soil scientist examines damage to cotton crop caused by excess salinity in the San Joaquin Valley, Calif. 36 ● Use of Mode/s for Water Resources Management, Planning, and Policy

Figure 2.—Surface Water Pollution Problems From Point Sources (municipai and industrial waste) (as identified by Federai and State/Regionai study teams)

Explanation Area problem Area in which significant surface water pollution from point sources is occurring Unshaded area may not be problem-free, but the problem was not considered major Specific types of point source pollutants Coliform bacteria from municipal waste or feedlot drainage PCB (polychlorinated biphenyls), PBB (polybromated biphenyls, PVC (polyvinyl chloride), and related industrial chemicals Heavy metals (e.g., mercury, zinc, copper, cadmium, lead) Nutrients from municipal and industrial discharges Heat from manufacturing and power generation Boundaries Water resources region Subregion SOURCE: US. Water Resources Council, The Nation’s Water Resources, 1975-2000, Volume 1: Summary, December 1978. Ch. 2—Introduction to Water Resource Models . 37

Figure 3.—Surface Water Pollution Problems From Nonpoint Sources

Explanation Area problem Area in which significant surface water pollution from nonpoint sources is occurring Unshaded area may not be problem-free, but the problem was not considered major Specific types of nonpoint source pollutants

● Herbicides, pesticides, and other agricultural chemicals

Irrigation return flows with high concentration of dissolved solids

● Seawater intrusion

o Mine drainage

Boundaries

— Water resources region

● “-..... Subregion

SOURCE: U.S. Water Resources CounciL The Nation’s Water Resources, 197fKW00, WMume 1: Summary, December 1978 able supplies and aquifer yields from individual aqui- In some areas, however, the excessive use of fers is a pressing need; models are widely used tools ground water has stopped too late. Major drops in for managing, regulating, and planning the use of ground water levels have caused the land to settle ground water. Models can be used to design a well or subside, damaging buildings, roads, and rail- field for greatest efficiency, to assess the extent of roads, and causing flooding in coastal areas. Sa/t- usable supplies, and to predict water-level declines water intrusion-penetration of underlying saltwaters resulting from alternative development schemes. into the freshwater layer—has also been caused in 38 Use of Models for Water Resources Management, Planning, and Policy

Figure 4.—Ground Water Overdraft and Reiated Probiems

1 I -1

Explanation

SOURCE: U.S. Water Resources Council, The Nation’s Water Resources, 1975 -2(W0, Volume 1: Summary, December 1978. coastal areas by excessive pumping. Similarly, Many ground water users are now attempting ground water overdrafting may draw poor quality to manage the conjunctiue use of ground and surface ground water near the land surface into deeper, waters to assure adequate water supplies. When high-quality ground water reservoirs. The likeli- available, surface waters are used to meet demands, hood of encountering these problems in a particular while ground water is relied on primarily during community or region can be assessed with models. dry periods. Ground water aquifers are often hy- Models can also help to evaluate management strat- drologically connected to surface lakes and streams; egies to minimize the risk of such occurrences. models can be used to analyze their interaction and Ch. 2—introduction to Water Resource Models 39 aid in their combined management, providing in- Part of the need to consider the social impacts of formation about both quantity and quality aspects many water resource programs and projects stems of ground and surface water interrelationships. from the uneven distribution of benefits and differing perceptions of the effects by various groups. In the past, ground water was generally consid- Models can assist the decisionmaker by both orga- ered to be a reliable source of high-quality water. nizing information on the social implications of a Yet pollutants from many sources enter the ground project and determining what social effects may oc- water system, though the extent and seriousness of cur and who may be affected. contamination has only recently been recognized. Moreover, the ability of aquifers to rid themselves Closely associated with social impacts are the of pollutants is limited by the slow movement of regional economic development implications of water ground water. resource policies and projects. A new reservoir might stimulate increased recreational activities that Accidental ground water pollution frequently subsequently attract new businesses to an area, or went unnoticed due to the ubiquitous nature of make a region more desirable for siting industries contamination—from road salt, oil and gasoline, or utilities. Models have been developed that pro- and other chemical spills and leaks. Waste disposal ject changes in the level of local or regional eco- has also been a major source of ground water nomic activities resulting from water resource pro- contamination. Wastes are sometimes injected in- grams and projects. to deep wells, which, if improperly designed, can contaminate drinking water. Toxic chemicals have The desirability of a project or policy may often found their way into ground water from municipal be studied using a benefit/cost analysis, which attempts and industrial landfills and dumps. Seepage from to assess relative economic efficiencies, weighing septic tanks has for many years been recognized the monetary benefits of a project against economic as a major source of bacterial contamination of costs. Models can be used both to assist in measur- ground water. In addition, agricultural pollution of ing the benefits and costs and to undertake the ground water can occur from pesticides, fertilizers, benefit/cost analysis itself. and salts leached from the soil by irrigation waters. The costs to industry of pollution control can also have Once contamination occurs, the time and cost of economic implications that affect such factors as in- reversing the process can far exceed the cost of dustry location and national inflation levels. Models preventing it. Models can be used to estimate the are used to determine the impacts of these costs on infiltration of these pollutants into ground water economic indicators like the Consumer Price In- and the movement of contaminated water through dex and the gross national product, as well as to an aquifer. They also have potential for aiding the determine the impact of these costs on specific in- design of waste-disposal landfills and injection wells dustries. to minimize the potential for polluting ground water. Since the economic and social effects of water- related development extend beyond a project’s im- Shortages of water, poor water quality, and mediate location, it is often important to analyze flooding have obvious effects on society. Perhaps these effects on a regional basis. Water resource less obvious are the indirect economic and social strategies can be developed through unified river basin effects that result from efforts to ensure or enhance planning and management, in which projected water water supplies and quality. The construction of a use demands, water quality objectives, and numer- multipurpose reservoir, for instance, will bring an ous secondary considerations, including desired influx of construction workers from outside the local levels of economic development, are balanced and community. A part of the salaries these workers re- coordinated. Models are useful in many aspects of ceive will be spent within the community, thus stim- such planning. ulating the local economy. An increased population, however, may also tax the local community’s Another analysis that is often necessary in the ability to provide adequate services such as educa- project-planning process is the consideration of un- tion or police protection. certainty. Risk/benefit analysis weighs the proba- 40 ● Use of Models for Water Resources Management, Planning, and POliCY

bility of some outcome—a flood or drought— tion of expensive, large-capacity structural supply against the benefit that would potentially be de- systems and the necessity for regulating water use. rived, for instance, if a reservoir were built to Models can determine the effects of water pricing on mitigate the impacts of these floods or droughts. use by analyzing consumer response to price. Models can help evaluate both the risks and benefits involved in projects to aid decisionmakers in deter- For regional and national analyses, forecasting mining acceptable levels of risk. water use requires an evaluation of population and economic growth, employment, industrial expan- One influence on present use of water is price; sion, etc. to project future water needs. Models can raising the cost of water can reduce demand in some estimate future levels of water use both by project- sectors, especially agriculture. This economic ap- ing past economic and demographic trends and by proach to conservation is particularly important be- simulating the relationships between these factors cause it can alleviate both the need for construc- and water use.

CASE STUDY OF MODEL USE: WATER RESOURCES IN LONG ISLAND, N.Y.

On Long Island, N. Y., water is a critical resource. Ground water is the sole source of drinking water for the island’s 3 million residents and is endangered by contaminants from leakage of septic tanks, landfills, and other sources. Along Long Island’s coast, rapid overdrafting of ground water has caused the intrusion of saltwater into freshwater . aquifers. In addition, Long Island’s rivers, bays, and estuaries, foundations of a fishing and tourist- based economy, are threatened by domestic and industrial wastes. In the past, contamination from these wastes has resulted in bans on fishing and the closing of public beaches. In 1970, the Nassau-Suffolk Regional Planning Board found that the most obvious limit to future growth on Long Island was the availability of pot- able water. The board developed a Comprehensive Land Use Plan, which recommended seeking additional funds to conduct water quality studies on Long Island, and provided an impetus for more rational management of the island’s water resources. Soon after, section 208 of the Federal Water Pollution Control Act of 1972 became the vehicle for undertaking these further studies and developing a regional strategy for treating and disposing of domestic and industrial waste. The Ch. 2—introduction to Water Resource Models 41

Nassau-Suffolk Regional Planning Commission it or allow it to infiltrate into the aquifer. The com- was designated as the local agency responsible for mission also considered nonpoint sources of wastes carrying out this investigation. and alternative means of controlling them—zoning, street cleaning, special agricultural practices, etc. In designing a waste management strategy, the commission relied heavily on models to provide a The commission had to use several models to quantitative framework for making management evaluate the various alternatives. First, to deter- decisions. a While water quality conditions were di- mine the quantity of water and the amount of pol- rectly measured whenever possible, the geographic lutants originating from nonpoint sources, the com- scope of the island and the expense of drilling test mission utilized a water budget model. For a given wells to analyze groundwater conditions precluded quantity of precipitation, this model projects the extensive direct measurement. The executive direc- amount of water that will infiltrate the aquifer; tor of the Nassau-Suffolk section 208 study noted return to the atmosphere via evaporation or plant that a wide variety of models was necessary to pro- transpiration; or reach rivers and streams overland. vide information for evaluating alternative waste Changes in land-use practices—particularly the management strategies and plans: construction of impervious surfaces, like parking lots, and the removal of vegetation—alter the pro- Long Island’s $5.2 million 208 study could not portions of ground water infiltration, evapotranspi- have been completed without the application of management, physical, chemical, analogue and ration, and runoff. The water budget model can hydrogeological models. These models were neces- respond to actual or hypothetical changes in land sary to help replicate a 1,200 square mile, geologic- use by estimating changes in the proportional dis- ally complex area. g tribution of precipitation. In most cases, with increasing development, recharge to the aquifer The nature of the management decisions facing decreases, while runoff normally increases. Long Island also favored the use of models. To minimize the environmental impact of a wastewater An increase in overland runoff tends to increase treatment plant, for example, it is necessary to eval- the load of pollutants discharged—e. g., sediment uate many alternative sites to determine its opti- from construction areas, grease from urban streets, mum location. The time and resources available and fertilizers from agricultural land. Runoff can for measurement limits the number of alternatives thus contribute a major source of contaminants to that can be evaluated. Models can help eliminate water bodies such as the Peconic River and Flan- less desirable alternatives, focusing time and ders Bay. The water budget model can be extended resources for detailed field testing on the most feasi- to estimate the load of nutrients contained in ur- ble sites. ban runoff and the total input of these nutrients to the bay. Thus, as a planning tool, the water Several options, for example, were available for budget model can be used to: 1) estimate the ef- managing the wastes of the Riverhead-Peconic area fects of altering land-use practices to reduce excess of Long Island (fig. 5). One or more regional, sub- runoff and ensure recharge of ground water; regional, or local sewage treatment plants could be 2) estimate the effects of altering land-use practices constructed to handle domestic wastes; alternative- to reduce sources of nonpoint source contaminants; ly, wastes could be diverted to the existing River- and 3) determine the relative amounts of total bay head plant. One factor in the decision was the rela- and river system contamination contributed by tive impact of waste discharges from the various nonpoint sources. treatment alternatives. Several options were again available: dispose of the wastewater in Flander’s Other models are used to predict the impact of Bay, discharge it into the Peconic River, or inject waste discharges from point sources on the Peconic River and Flanders Bay. These models simulate 8 The Long ~s[and Comjvehenslue i~’aste Treatment .~ana{ement plan, \’o]- the currents and circulation patterns of these water ume 1 : Summary Plan; \’olume 2: Summary, Documentation ( Haup- bodies and project the transport and fate of pollut- pauge, .N, Y.: .Nassau-Suffolk Regional Planning Board, 1978), ‘Lee H Koppelman, personal commu nicat ion to OTA staff, No\, ants once discharged. Different models must be 24, 198] used for the river and the bay because of differences

c 1– . I – c - 42 . Use of Mode/s for Water Resources Management, Planning, and Policy

Figure 5.—Riverhead-Peconic Area, Long Island, N.Y.

r-~ (n 6“ South

c m Peconic

& Flanders Bay , *

Calverton

p econl ~swan POnd pond Lake Cedar .7

Wildvw30d Lake “charge %w ESTPl Sewage Treatment Faclllty Alternatives d::::.?.]

~BellowS Pond

SOURCE: The Long Island Comprehensive Waste Treatment Management Plan, vol. 2, figs. 7-27, 7-28. Ch. Z—Introduction to Water Resource Models ● 43 in their currents and circulation patterns. Not all areas of a bay or river disperse pollutants equally; e.g., some sections of Flander’s Bay are isolated from its primary circulation patterns. Since nutrients stimulate algal growth, which can severely affect water quality, it is advantageous to rapidly disperse wastewater discharges to the bay. The river and estuary models can assist in determining an acceptable location for wastewater disposal. The river and bay models assume that the growth of algae in these water bodies depends primarily on the concentration of nutrients from waste discharge, However, other factors like ‘‘grazing’ of the algae by herbivorous zooplankton and recycling of nutrients from decomposing organic matter also influence algal populations. To account for these factors, the commission used an ecological model that simulates algal growth more accurately, The ecological model more fully explores the impacts of both point and nonpoint source discharges on the bay ecosystem. An alternative to discharging wastewater to the bay or river is to discharge treated effluents by either injecting them directly into the ground water or allowing them to slowly percolate into the aquifer. These approaches have the potential advantage of recharging declining ground water levels; however, they could also contaminate the ground water. Photo credit: O Ted Spkge/, 1982 Several different models were used to assess the im- Construction crews prepare a wastewater injection well pact of recharging ground water with wastewater on Long Island. Wastewater will be pumped directly into in the Riverhead-Peconic area. One model type the ground water table to prevent saltwater intrusion. projects the effect of recharge on the height of the Prior to construction, models were used to assess the injection well’s potential to recharge (elevate) ground water table and the flow and distribution of recharge water levels, as well as to assess the possibility that water in the aquifer. wastewater could contaminate ground water supplies A second model describes the way in which pol- pie, while a model may help to guide the selection lutants are transported with ground water flow. of an adequate location for releasing treated sewage This type of model is used to estimate how a leak- outflows in terms of water quality considerations, ing septic tank, an injection well, or a recharge it does not consider many other factors, like a site’s basin will affect ground water quality. recreation or habitat potential, which are necessary

It is important to note that these models are not aspects of the decisi~nmaking process. Models are designed to make management decisions them- virtuall y indispensable, however, for their ability selves. Many qualitative and quantitative consider- to both describe and project, in a quantitative ations that affect management decisions are not framework, the effects of alternative management within the scope of the models’ analyses. For exam- decisions. Chapter 3 General Issues in Model Development, Use, and Dissemination Contents

Page Support Services for Disseminating and Using Existing Models Effectively . 47 Documentation ...... 48 Informing Users of Available Models ...... 49 Training ...... 50 User Assistance ...... 51 Maintenance and Improvement of Models ...... 52 Additional Model Characteristics Affecting Ease of Model Use ...... 52 Issues in the Development and Use of Models ...... 53 Interaction Between Modelers and Decisionmakers ...... 53 Evaluating Models for Use by Water Resource Managers ...... 55 Mechanisms for Assuring Adequate Oversight of Model Development ...... 59 Legal Aspects of Model Use in Administrative Processes ...... 61

FIGURE

FigureNo. Page 6. Comparison of Measured and Computed Runoff for the Storm of Aug. 2, i963—Oakdale Avenue Catchment—EPA Stormwater Management Model 57 Chapter 3 General Issues in Model Development, Use, and Dissemination

Models are increasingly used to analyze a wide hand and mid- and upper-level managers on the variety of resource issues because they can provide other. Yet decisionmakers are often unprepared to information that is either unavailable from other involve themselves in the modeling process, and sources, more accurate than that provided by other may consequently be uncertain of how to use model sources, or quicker and less costly than that pro- results. Similarly, modelers may be equally un- vided by other sources. However, as with many prepared to build models that provide the kinds of new information technologies, institutions have en- information decisionmakers need. For institutions countered problems in integrating modeling and to make effective use of models, links must be model-generated information with established oper- created among modelers, model users, and deci- ating procedures, professional responsibilities, and sionmakers, and effective incentives be devised to channels of communication. make model development and use an interactive process among them. Further, institutions need to When modeling efforts are supported by public develop procedures for evaluating the models they funds, institutions that develop models have respon- use, overseeing model development, and assessing sibilities for ensuring the availability y and usability the legal implications and consequences of their of such tools for other institutions. To effectively model use. carry out these responsibilities, model-sponsoring organizations must devise strategies to inform This chapter reviews the major issues associated potential users of the existence of relevant models, with the development, use, and dissemination of ensure that the model’s purpose and workings are water resource models. Many of the significant explained in writing so that decisionmakers can problems associated with current model use for determine its applicability to a given problem, and water resource analysis are encountered throughout disseminate the model to those who request it. Ad- the modeling profession; they tend to reflect the ditional support services include developing pro- newness of the modeling field, and institutional un- grams to train and assist users to operate models preparedness for overseeing, supporting, and guid- and interpret results, maintaining and improving ing model use. existing models, and designing models for ease of use by other institutions. The chapter is comprised of two major secf “ens:

The process of developing and using models also Support Services for Disseminating and Using Ex-

requires extensive consultation between highly isting Models Effectively; and Issues in the trained technical and scientific personnel on one Development and Use of Models.

SUPPORT SERVICES FOR DISSEMINATING AND USING EXISTING MODELS EFFECTIVELY

Once a model is operational, any potential user quate user-oriented support services, it is likely to normally needs a great deal of information from remain unused by anyone other than its developer. the developer if he or she is to become proficient Within the modeling profession, such support serv- in running the model and interpreting its results. ices are called technology transfer and assistance. This A model may have been rigorously developed and section discusses those aspects of modeling that aid thoroughly evaluated, yet in the absence of ade- users in employing an existing model. Five sup-

47 48 . Use of Models for Water Resources Management, P/arming, and Policy port activities are treated in depth; the section con- ly developed command of technical computer lan- cludes with an overview of additional model charac- guages—it is in these languages that they actually teristics that are linked to technology transfer ca- work. Documentation requires translating the in- pabilities: structions written in these languages into clearly understandable English. The task is not only time- ● documentation; consuming— a medium-sized computer program ● informing users of available models; may consist of 4,000 sets of instructions—but it is ● training; also one for which a technical specialist may have ● user assistance; little skill or motivation. The developer of a model . maintenance and improvement of models; and has no inherent need for documentation, other than . additional model characteristics affecting ease as a reminder of what he may forget. Documenta- of model use. tion is principally for successive users, and few incentives currently exist for the developer to take user Documentation needs into account in the process of model develop- Documentation is the process of setting out ex- ment, plicit written instructions on how to use a model Consequently, for most models, documentation and interpret its results. Although documentation either does not exist, or exists in inadequate form, is critical to the proper use and dissemination of lacking in detail, and failing to serve users’ needs. 1 models, it is rarely carried out adequately, and is Model documentation is typically so brief or poorly considered by professionals to be one of the most written that the user is forced to resort to a trial- neglected aspects of modeling. The lack of proper and-error approach to learn proper use of the mod- documentation prevents potential users from dis- el, or to seek personal assistance from those who covering existing models that suit their needs— developed the model. causing costly duplication in model development— Documentation is the primary mechanism for in- and increases the difficulty and cost of using previ- formed communication among those involved in ously developed models. modeling efforts —developers, users, analysts, and Documentation has two purposes. First, it pro- decisionmakers. Without it, the purpose, premises, vides a nontechnical description of the basic con- and capabilities of the model remain obscure, and cepts employed in a model, and its limitations. Such it becomes impossible to: 1) decide whether a model a description must include sufficient information applies to a given problem, 2) operate the model to allow a decisionmaker to determine whether a independently of the developer, and 3) adequately given model is suitable (and available) for a specific interpret and use model results. 2 Further, compe- use. Second, it provides technical information on tent documentation is important in facilitating mod- the basis of which a user/analyst can evaluate, du- el evaluation by third parties, and in encouraging plicate, and operate the model. Three kinds of doc- continued maintenance and updating to keep mod- uments are generally used to document computer els current. models: Few institutions encourage proper documenta- 1. a detailed description of the model’s purpose tion. Seldom are funds specifically provided for the and assumptions; documentation phase of model development. Even 2. users’ manuals, which give instruction on run- when funds are provided, if the funding organiza- ning the model—i. e., how to prepare input tion lacks a unit that critically evaluates documen- to get the desired output; and tation in the context of using the model, developers 3. programmers’ manuals, which explain the model’s logic and internal functions, enabling the user to adjust and adapt the model to fit his ‘S. Gass, Computer .ilodel Documentation A Retleu and An Approach, NBS Special Publication 500-39, National Bureau of Standards, 1979. particular needs. ‘G. Fromm, W. L. Hamilton, and E. E. Hamilton, Federa[~ Sup- ported ,Vlathematzca[ .h!ode[s Surue) and AnalYsz~, Gp(l stock Good documentation is difficult to prepare. Mod- #038 -000-00221-0 (Washington D. C.: Gmernmcnt Printing Office, elers and computer programmers usually have a high- 1975), p. 44, Ch. 3—General Issues in Model Development, Use, and Dissemination ● 49 may have little incentive to spend time and effort mitted manuscript, causing significant delays in on the quality of their documentation work. In most communicating the availability of a model. modeling efforts, documentation is done ‘‘after the fact, as part of the cleanup operation at the end Three ways to make information on existing of the project, necessitating searches through old models available to potential users were suggested records at a point when both time and money are at the OTA workshops: 1 ) catalogs, 2) newsletters, in short supply. and 3) model clearinghouses. Moreover, modelers and programmers have little professional incentive to produce high-quality Catalogs documentation work. Documentation is a long and tedious process. Most developers see it as noncre- Various Government agencies and research orga- ative, in that it calls not for analytical or technical nizations have published catalogs of available mod- skills, but rather for communicative abilities that els. Such attempts to distribute model information the modeler frequently lacks. At present, documen- have had mixed success. In the rapidly advancing tation is also seen as contributing little or nothing field of modeling, many catalogs quickly become to the modeler’s standing in his field. outdated, since new models are regularly introduced and old models must continually be updated If documentation is to be upgraded, it must be- to remain current. Consequently, the maintenance come an integral part of model development. The and updating of a usable catalog must be performed most efficient mode of creating written documenta- on a continuing basis by a staff with relatively high tion is to do so concurrently with the development levels of expertise. of the model—this helps to ensure that the written instructions accurately reflect the actual computer A number of Federal organizations have included program. model-related information in catalogs dealing with water resources—most importantly, the Selected Informing Users of Available Models Water Resources Abstracts and the Water Resources Research in Progress File Catalog of the Water Although numerous models are available to assist Resources Scientific Information Center. and var- water resources managers, these models are difficult ious publications of the National Technical Infor- for users to identify, locate, and obtain. OTA found mation Service. However, these services are not that many potential model users, and even modelers designed to rapidly access modeling information, themselves, considered the need for effective com- and are too far removed from developers to be ex- munication about existing models more important tensively used or adequately maintained. than the need for developing new models. Fre- quently, the difficulty of identifying and locating In addition, the Federal Software Exchange Cen- a suitable model causes the decisionmaker to either ter (FSEC) publishes catalogs of computer pro- forego model use for water management decisions, grams that Federal agencies consider to be usable or leads to the development of a new model. De- by other Federal, State, and local government agen- veloping new models is extremely costly and time- cies. However, the catalogs are not intended to pro- consuming, while existing models that have been vide comprehensive coverage of even federally de- evaluated may need only minor adjustments and veloped models, and provide relatively scanty infor- ‘ ‘fine tuning’ to be applied to the user’s problem. mation regarding the models that have been included, Moreover, FSEC regulations prohibit dis- Presently, most information on existing models closure of the identity of the developing agency is available only in technical journals. These tech- without its prior consent, frequently precluding fur- nical publications are geared primarily to use by ther inquiries by and assistance to potential users. scientists and modelers. Few journals aim to communicate with decisionmakers and managers, and An extensive discussion of the functions of these their distribution is often limited to a handful of organizations that relate to modeling is provided subscribers. Most take over a year to publish a sub- in chapter 4 of this report. 50 . Use of Models for Water Resources Management, Planning, and policy

Newsletters specific problem, would submit information on the nature of the pertinent water resource problem and Newsletters are a useful vehicle for disseminating on any other requirements that influence the choice information about available models. An organiza- of a model—such as cost, level of complexity, as- tion can publish newsletters relatively inexpensively sumptions of the model, etc. In turn, trained clear- as a service to current and potential users of its inghouse staff could quickly locate models that gen- models. Newsletter services for the Environmen- erally fulfill these requirements. tal Protection Agency’s (EPA) Stormwater Man- agement Model (SWMM) Users’s Group and the Clearinghouses can provide assistance in other EPA Center for Water Quality Modeling are de- areas as well. State survey respondents indicated scribed in chapter 4 of this report. a need for information on sources of technical assistance, training, and data, as well as information on Model Clearinghouses existing models. Some respondents suggested that clearinghouses serve as technical assistance and Clearinghouses offer a comprehensive approach training centers. Clearinghouses could also have for disseminating information about models evaluative functions —developing standards for as- available from a broad range of participating agen- sessing the materials submitted, and providing tech- cies and organizations. Model clearinghouses serve nical help in evaluating the utility of available as a central resource for obtaining information choices. about available models, and help to address such modeling problems as duplication of model develop- It is unlikely that a clearinghouse could initially ment efforts, and improper selection of models. be self-financing. Seed money would invariably be needed to get it started, and outside funding might A clearinghouse’s primary function is to collect be needed throughout its existence. Clearinghouses models and model-related information, and dissem- could be partially funded by private business or inate these models and information to the user com- Federal agencies, and earn the remaining necessary munity. The majority of persons contacted for this operating funds by charging for their services. study indicated a strong need for a model clearing- Another option is for the clearinghouse to conduct house. One established clearinghouse for ground and charge tuition for training courses, which would water models at the Holcomb Research Institute publicize the organization as well as generate is discussed in chapter 4 of this report. income. Of those surveyed by OTA, most who favored the model clearinghouse concept felt that the clear- Training inghouse’s primary or central role should be to inventory existing models. This inventory might con- User training is among the most effective means sist of a central catalog of models by subject area, for improving the use of water resource models. a list of available models, a list of agencies that use Both model developers and model users who were models, and a notation of a contact person or agen- contacted during the OTA study consider training cy for further information about each model. For an important aspect of model support. At the pres- Federal agencies, an inventory would help avoid ent time, neither governmental water resource duplication of existing models and could improve agencies nor the private sector are providing the interagency coordination of modeling efforts. For necessary training for applying models to the deci- State agencies, an inventory would serve as a source sionmaking process. In response to an OTA survey, of information on available state-of-the-art model- State-level water resource professionals ranked fed- ing tools. erally sponsored training a priority second only to data needs, and indicated a need for training assist- To meet model users’ needs, the clearinghouse ance in all phases of modeling activities. could also establish a catalog of model characteristics to help users compare the advantages and disad- Several mechanisms can be employed for train- vantages of different models. Users seeking infor- ing model users and decisionmakers. Individuals mat ion on a particular model, or on models for a surveyed for this study generally agreed that one- Ch. 3—Genera/ Issues in Model Development, User and Disssemjnatjon . 51

Photo credit: Ted Spiege/, 1982 A senior hydrologist at USGS headquarters in Reston, Va., demonstrates steps in modeiing river currents. A tape from the underwater monitoring equipment pictured in left foreground provides data as input to the model, which is run on the computer terminal above. A portion of the model converts numerical information into charts and maps of current patterns in the river itself. to-one interaction between developer and user is report. Some agencies are using videotapes of train- the most successful training approach; however, it ing sessions as less expensive teaching tools. other was also identified as the most expensive training innovative techniques may be applicable-. to train- method. Hands-on workshops, which allow users ing model users, including programed teaching aids to run models on computers under supervision, and self-instruction methods. were identified as the next best method. Traditional seminar approaches were the third choice for user User Assistance training. Documentation, training, and other user aids can A number of Federal agencies conduct user train- go a long way in preparing the decisionmaker for ing programs. The U.S. Geological Survey con- using water resource models. However, direct as- ducts numerous courses in many aspects of mod- sistance by experienced modelers and computer eling, while the Army Corps of Engineers’ Hydro- programmers will often be needed. Sometimes the logic Engineering Center (HEC) provides exten- problem can be solved simply by a phone call; at sive training courses in the use of its major models. other times, direct contact with a modeler or pro- The Instream Flow Group (IFG) at the Department gramer who is familiar with the model may be of the Interior specializes in training both managers needed. and technicians in instream flow analysis, problem solving, and related model use. Federal training ef- User assistance may range from merely pro- forts are described in detail in chapter 4 of this viding information on the status of a new model, 52 . Use of Models for Water Resources Management, Planning, and policy —.—. — ——— ——— ————. ———————— -— -———

to advising on model application or preparing in- in the following section, Issues in the Development and put data and analyzing results. User assistance also Use of Models), there are other factors that affect the helps the modeler to better understand the problems value of models as aids to decisionmakers. These of applying models by interacting with the deci- incude: sionmaker-user. Complex models may even require 1. computational efficiency-is the model Cost ‘‘tutored application ‘‘ in which modeling specialists effective in terms of computer use; and users work together in applying the model to 2. ease of use—is the model understandable and the user’s problem. Federal agency user support easily operable by users; and groups that have devised procedures for assisting 3. transportability-is the model designed for use users include the SWMM User’s Group, HEC, on a range of different computers? and IFG. Their experiences in this area are described in chapter 4 of this report. Computational Efficiency Maintenance and Improvement Computational efficiency pertains to computer of Models costs associated with operating a model. It is generally achieved by carefully designing the model to The development and improvement of models make the best use of the capabilities of a particular seldom stops at evaluation and fine-tuning for real- computer and by applying state-of-the-art proce- world applications. Models are constantly modified dures for manipulating and solving equations with- and improved based on users’ experience, new in- in the model itself. formation, or new methodologies and techniques. Each change in a model must be documented, and Ease of Use the users notified of the modification and ad- The ease with which a model can be used de- justments in operating procedures that it requires. pends on the design of its input and output char- It is important that the institutions that sponsor acteristics. The input characteristics of a good and support model development make provisions ‘ ‘user-oriented’ model, i.e. , a model that is de- for updating and maintaining models after they signed for use by persons other than the modeler, become operational. Unfortunately, history has ensures that information and data needed for run- shown that few institutions, whether Government ning the model can be introduced into the model agencies or academic institutions, provide for the with the least effort and with minimum chances for contingencies of model updating and maintenance. errors. Such a model checks the data for com- Clearinghouses or central repositories can play an pleteness and reasonableness, and transforms it into important role in ensuring that models are updated usable form for processing. The output of a good and improved. OTA workshop participants sug- user-oriented model can be adjusted to provide the gested assigning ‘ ‘lead agency’ responsibility to a level of detail and organization of information that Federal Government entity for systematically track- best suits the user. If a computer run cannot be ing Government-wide model development and up- completed due to errors or incompatibility of data, keep. an effective model will provide an analysis of the problem encountered (diagnostic information), and Modeling support groups such as HEC are effec- will warn when computer-generated information tive means for assessing model deficiencies, main- exceeds predetermined bounds. taining and improving a model, and notifying users of subsequent changes in a model. Transportabilit y

Additional Model Characteristics Model transportability is the ease with which Affecting Ease of Model Use models can be transferred from one computer system to another. Characteristics of computer systems

In addition to the technical assessment of a mod- vary substantially among manufacturers. A model el’s capabilities and the qualitative evaluation of designed to take full advantage of the various fea- its credibility through operational testing (described tures of a particular computer system, e.g., for stor- Ch. 3—General Issues in Model Development, Use, and Dissemination ● 53 — —.- ing information or solving equations, may need often results in sacrifices of computational efficiency major revisions for use on another computer sys- and ease of use. tem. Costs associated with restructuring and Designing for transportability requires knowl- retesting models can be substantial. If a model is edge of the characteristics of a variety of computer intended for use on a number of different computer systems. Such knowledge is difficult to acquire and systems, the modeler must avoid using system- is not widespread among model developers, since dependent features of any particular computer it must be gained through operating experience on system. However, designing a transportable model a range of computer systems.

ISSUES IN THE DEVELOPMENT AND USE OF MODELS

The model development process begins when a Because modeling is a relatively new field, few decisionmaker, scientist, or manager identifies an decisionmakers have had an opportunity to use information need that can best be met through some models as part of their formal education, or to par- form of mathematical analysis. A team of profes- ticipate in model development processes. While this sionals subsequently analyzes the issue and gathers trend is changing as a new generation of water re- data on it, develops the mathematical equations that source managers assumes positions of responsibil- comprise the model, fine-tunes the model to specif- ity, lack of familiarity with models and modeling ic conditions, evaluates model results, and presents concepts remains a key impediment to increased the model-generated information to the individual reliance on model-based information. Individuals requesting it. Oversight from the supporting orga- contacted or surveyed by OTA repeatedly stated nization must be provided to assure that model that models are not used in many water resource development proceeds effectively, and that model areas because ‘ ‘they are not trusted’ by those results are appropriately used. This section assesses responsible for management and decisionmaking. four major aspects of the process of developing and Conversely, models tend to enjoy high levels of using mathematical models: credibility among users and decisionmakers who are familiar with modeling techniques and with the ● interaction between modelers and decision- results of specific models. makers; ● evaluating models for use by water resource Managers who are inexperienced in the use of managers; these techniques tend to base their judgments about ● mechanisms for assuring adequate oversight the value of models on the experience of others. Dr. of model development; and William Johnson of HEC observed that ‘ ‘the cll- ● legal aspects of model use in administrative terion of trustworthiness is determined by an ac- processes. ceptable record of use (preferably by those other than the model developer). Results of OTA Interaction Between Modelers surveys and workshops on modeling* suggest that and Decision makers the use of models in water resources management can be broadened by a concerted effort to familiar- The goal of the modeling process is normally to ize resource managers and decisionmakers with the provide results that are usable in decisionmaking development and operation of mathematical mod- processes—including day-to-day operations and els. management, medium- and long-range planning, regulator y purposes, and policymaking. To effectively aid decisionmaking, models must provide information that is relevant to the decision alternatives at hand. In addition, model results must be considered reliable by those responsible for making decisions. 54 ● Use of Models for Water Resources Management, Planning, and Policy

When a decisionmaker initiates a model development effort, the value of the information he ultimately receives depends directly on his ability to specify what he needs to know. Yet many professionals routinely state their information objectives in qualitative terms, and their conception of the problem to be solved may not lend itself to quantification. Decisionmakers may also look to the model to explain the issue, when in fact a clear specification of the issue is a prerequisite to developing models of it. A modeler who is confronted with an imprecise request for information will normally attempt to provide the kind of results that he or she considers critical to the decision—often without success. Mod- elers usually have a technical or scientific background that is significantly different from that of the decisionmaker, although there are some exceptions. Without inputs from decisionmakers, modelers may tend to concentrate on ‘ ‘technically cor- rect’ solutions without regard to political considerations that may affect the outcome of a decision.

Photo credts: @ Ted Spiegel, 19S2 Evidence that PCB levels in the Hudson River had the potential to interfere with commercial shad fishing led the New York State Hudson River Valley Commission to develop models to analyze the problem Ch. 3—General Issues in Model Development, Use, and Dissemination ● 55

Modelers may also have professional motivations The modeler-decisionmaker team needs to en- that lead them to concentrate on developing model- sure that four questions are continually addressed ing techniques and mathematical sophistications for during model development or use: the primary purpose of advancing the state of the ● Are we developing or using the model to modeling art. Rewards are frequently given on the answer the proper questions? basis of professional contribution to the field of ● Is the model capable of producing sufficient- modeling rather than for developing models that ly accurate answers? have utility for the decisionmakers. A 1975 survey ● Will the model be an improvement over exist- of model development project directors conducted ing techniques? by Fromm, Hamilton, and Hamilton,3 found that ● Will the improvement in results justify model the two most frequently identified benefits of model- costs? ing were: 1) ‘ ‘educated the model builders’ (78 percent); and 2) ‘‘pointed a way for further research’ Neither model developers nor decisionmakers (76 percent). ‘‘ Helped in making policy choices’ can answer these questions in isolation from each ranked only fifth (58 percent). The modeler’s preoc- other. But bringing the expertise of each group to cupation with advancing the state of the art of bear jointly on model development and use is in modeling, while highly useful for anticipating future itself a complex undertaking. Creating appropriate needs and identifying critical emerging issues, often incentive structures in institutions where modeling leads in the short run to overly complicated models activities take place can have a major influence on that require more information and data for their how well the interested parties work together to pro- use than is practically available to the user/decision- duce appropriately designed models. The profes- maker. sional climate established by top policymakers plays an important role in encouraging the use of models, Finally, unless the modeler thoroughly instructs training decisionmakers to use models effectively, the decisionmaker on how to interpret model re- and stimulating the development of usable model- sults, the information provided may inadvertently ing tools. be misleading. By constructing the model, a modeler normally gains an appreciation of its capabilities and limitations—in particular the range of Evaluating Models for Use error associated with various model results. If the by Water Resource Managers decisionmaker is merely presented with a set of fig- Once developed, models must be evaluated to ures and projections, he or she may tend to overrely ensure that the information they generate adequate- on the model accuracy or misinterpret the mean- ly covers the range of conditions that the decision ing of the information produced. Such overreliance objectives demand. This requires not only an assess- may result in a misdirected decision, and cause the ment of the technical capabilities and limitations decisionmaker to avoid the use of models in the of the model, but also qualitative judgments con- future. cerning the nature and extent of the information The most effective way to avoid these pitfalls in needed for the decision at hand. model development and use is to ensure that mod- The evaluation process aims to answer three elers and decisionmakers interact and communicate questions concerning the model: with each other throughout the model development process. The institutional setting should encourage ● How well does the model’s structure corre- multidisciplinary approaches to problem solving, spond to the structure of events in the real involving scientists, modelers, model users, and world? Since models are simplified mathematic- manager-decisionmakers. The success of the model- al representations of real, complex relation- ing effort will often depend on stimulating and ships, we need to know how adequately such maintaining communications among these groups. simplifications reflect the essentials of these real-world relationships. Are the model’s assumptions about real-world behavior reason- 3Fromm, Hamilton, and Hamilton, op. cit., p 66 able? Does the model take account of the fac- 56 Use of Models for Water Resources Management, Planning, and Policy

tors that actually characterize and control the able and can be addressed by a procedure called real-world phenomenon? Is the model sensitive ‘ ‘validation. The third addresses the relevance of to changes in those factors that could affect the the information provided, and involves subjective real-world response? analysis of the nature of the problem being stud- How accurately does the model predict events ied. Modelers and decisionmakers must understand in the real world? What is the degree of possi- the outcomes of all three kinds of questions if they ble error gaged by some measure of perform- are to evaluate the models they use and the infor- ance? mation that models provide them. The following Does the model provide the degree of accuracy discussion outlines the major techniques used to and flexibility required by the user? Is infor- provide these answers. mation provided at an appropriate level of detail? Technical Assessment of Models The first question is conceptually the most diffi- Three technical procedures collectively determine cult, and requires both technical and qualitative the accuracy of a mathematical model: 1) verifica- analysis of any given model. The second is quantifi- tion—assuring that the computer program actually performs as designed; 2) calibration-developing values for the constants and coefficients in the computer program from field data, in order to accurate-

h ly predict real-world events; and 3) validation-as- + sessing the model’s accuracy in predicting real- world events. Verification. —A model is said to be verified when it is determined that the designer’s conception of the model is accurately embodied in the program written and run on the computer. Such a procedure is applicable to any model, and involves technical checks to ensure that:

● the written program accurately describes the model’s design; ● the program is accurately mechanized on the computer; and ● the mechanized program runs as expected. Verification of a computer model may require considerable effort to ‘‘debug’ (adjust the program so that it runs properly), particularly if the model is large and complex. Although the process of verification is straightforward, and to a large extent mechanical, the expense and time delays to debug a program can be significant. ‘i -*46P% Calibration. —Models must be “fitted’ or ‘‘fine- tuned’ to the specific characteristics of the real- Photo credit: @ Ted Spiegel, 1!?s2 world system being studied. Each model contains Researchers take ice core samples to measure PCB deposits at Thompson Island Dam, Ft. Edwards, N.Y. a set of parameters, i.e., values of coefficients, Often, data-gathering must be closely coordinated with that establish the relationship between the model’s modeling activities if models are to provide information predictions and the information supplied to the relevant to the problem at hand. Models can also be used to help pinpoint those aspects of the problem for which computer for analysis. A model is considered to be additional data collection is required calibrated when model results match experimen- Ch. 3—General Issues in Model Development, Use, and Dissemination ● 57 tal observations taken from the particular system ly new set of data, gathered at a different time or under investigation. Calibration is, thus, the proce- place than those data used to develop and calibrate dure used to determine a specific mathematical val- the model. However, in instances of limited data, ue for the parameters of a model. a single data set may be split, and the two halves be used for calibration and validation respectively. Calibration depends on a reliable set of data collected under conditions as similar as practical to The simplest validation measure is a graphic those prevailing at the time of the decision. Often, comparison of observed data and computed values. however, data are not available, and the modeler It allows the analyst to make qualitative judgments must depend on assumed values or average values about the adequacy of the model and its suitabil- observed previously for estimates of the parameters. ity for additional use, and provides a clearly visi- The use of assumed or hypothetical values often ble, easily understood assessment of model results. reduces the reliability of the model. An example of simple graphic comparison is present in figure 6. More complex models may require Validation. —Validation is the process of deter- statistical indicators of accuracy to supplement or mining how accurately the model can predict real- supplant graphic presentation. Simple statistical world events under conditions different from those measures comparing observed and computed values on which the model is developed and calibrated. include correlation coefficients, computation of To validate a model, a different set of field data relative error, and comparison of means. is used as input to the model and the output is compared to actual observations of the new field con- Validation depends on a reliable standard for ditions. Where possible, validation uses a complete- comparison. The lack of comparative data often

Figure 6.–Comparison of Measured and Computed Runoff for the storm of Aug. 2, 1963– Oakdale Avenue Catchment—EPA Stormwater Management Model

The graph above compares measured runoff to SWMM estimates of runoff for a single storm event at an individual stormwater catchment. Amounts of precipitation falling during the course of the storm are shown at the top, and are calculated by the scale at the right; actual and estimated discharge to the catchment is shown by the lower lines, and is measured by the scale at the left. SOURCE EPA Stormwater Management Model, 58 . Use of Models for Water Resources Management, Planning, and policy precludes adequate validation. If a model describes a model’s predictions are sufficiently reliable to a unique system or event, then comparisons with serve as an input to decision processes. data from other systems (or times) may be impossi- Three techniques can be used to assess complex ble. Some models, e.g., models of physical processes predictive models in a qualitative or semiquan- which are governed by law of physics and engineer- titative manner: 1) parts of a complex model can ing, are often adaptable for a wide range of applica- sometimes be validated independently of the re- tions. Such models can be validated from time- mainder of the model, using historical data to test series observations at a single location—comparing the accuracy of the projections; 2) professional con- results with prior historical data—or in combina- sensus can be obtained among experts who review tion with similar data from other locations. the reasonableness of the model’s parameters and Social and economic behavioral models, how- structure; and 3) users can perform sensitivity anal- ever, are difficult to validate in the strict sense. yses, i.e., comparing the changes in model output Human behavior cannot be analyzed in the same that result when the model is run successively with sense as interactions that take place in the physical small changes in model assumptions. Sensitivity sciences. Human interactions may be extremely analysis places less emphasis on the absolute accu- complex, and involve many factors not readily sub- racy of projections, and more on the differences that ject to quantification. At best, social scientists can result from incremental changes in policy, for ex- estimate statistical variations in human behaviors ample. under a set of assumed conditions— yet there is no The decisionmaker must be a major participant way to gage the likelihood that the assumed condi- in the qualitative assessment of a model. In the ab- tions will come to pass. This difficulty is com- sence of statistical and objective measures of per- pounded by the necessity to forecast changes in a formance, one must rely on the intuition and expe- number of highly uncertain economic and social rience of the decisionmaker in judging the quality variables, e.g., inflation, commodity prices, and of the information the model supplies and in weigh- demographic and employment patterns. Moreover, ing that against the informational needs for deci- the complex interactions of the economic and social sionmaking. Similarly, the user/decisionmaker systems are dynamic, i.e., the nature of the system must be the final arbiter in evaluating the sensitivity itself continues to change, thus requiring constant of the model to changing inputs and conditions. changes in the model. Under circumstances of changing system structure, it is nearly impossible Assessing the Relevance of the Model to use long-term time-series data for validating models. A major reason for expending the time, effort, and funds necessary for using a model is to pro- Qualitative Assessment of Models vide information that is not available from other sources. A model’s utility to the decision process Socioeconomic and integrated models are used depends both on its ability to analyze information by decisionmakers to predict the likely economic and on the relevance of the information to the deci- and social effects of policy decisions. As explained sions to be made. Thus, in the find analysis, the above, such models cannot be validated in the tech- decisionmaker must gage the usefulness of the mod- nical sense because there are no statistical means el against the profile of the decision itself. for assessing the accuracy of the model’s predictions until the predictions have come to pass—or In some instances, a model’s primary use may failed to do so. Moreover, the presence of factors be to identify further information that may be that have influenced the outcome but have not been needed to approach the decision; thus the evalua- included in the model may preclude any statistical tion of the model proceeds as an integral part of check on the model’s accuracy. One must therefore the issue analysis. The term forum analysis is rely on qualitative indicators of the model’s cred- sometimes used to indicate a procedure in which ibility and reasonableness to assess its usefulness a number of models are analyzed to determine their and reliability. Properly understood, such proce- relevance to a given issue. The forum analysis be- dures permit policymakers to determine whether gins as a comparative exercise, in which different Ch. 3—General Issues in Model Development, Use, and Dissemination ● 59

models that provide short-term forecasts of streamflow. 4 The project used data sets from six rivers with different physical and climatological characteristics to determine the models’ relative advantages and disadvantages for assessing streamflows in a variety of river types, and under differing institutional constraints and accuracy requirements. The exercise allowed participants in a technical conference to compare the performance of the tested models, and to develop guidelines for model selection based on such criteria as the purpose of the forecast, the prevailing climate within the river basin, and the quality and type of data and computers available.

Mechanisms for Assuring Adequate Oversight of Model Development Although there is broad agreement among the modeling community that additional measures are needed to standardize and improve the quality of models, there is significant disagreement among modelers as to how this should be achieved. Among the means of ensuring quality control of models are: guidelines, standards, contractual agreements, and peer review. Each of these could potentially limit the individual modeler’s flexibility and freedom to approach problems, hence any proposal to create Photo credit: @ Ted Spiegel, 19S2 standards and impose uniformity is a contentious Decisionmakers must understand the assumptions Issue. underlying model-generated information to use it in deciding policy questions Guidelines and Standards models are run with the same data set in order to Proponents of establishing Government-wide determine the fundamental differences in their pro- guidelines for model evaluation consider guidelines cedures and results. The information generated is an effective means of standardizing and ensuring then used as a focal point for examining the issue compatibility among model development efforts, itself, as participants attempt to specify the factors as well as a way to screen bad models while enhanc- that influence the situation in the real world, and ing the acceptance of good ones. Such guidelines to improve the model’s capacities to reflect those could promote uniformity in evaluation criteria, factors. The “forum’ for carrying out this assess- and contribute to achieving compatibility among ment simultaneously involves modelers, model ana- model results. lysts, and policymakers. Forum analysis can be a powerful tool to advance the state of the art of mod- Opponents point out, however, that the wide va- eling for a specific problem area, and can also con- riety of user needs may preclude the use of uniform tribute to a better understanding of the problem guidelines. Since a model needs primarily to match by providing an analytical framework for considering the issues. 4“Intercomparison of Conceptual Models Used in Operational Hy- A recent World Meteorological Organization drological Forecasting, “ World Meteorological Organization, WMO forum analysis project compared 10 hydrological No. 429, Geneva, Switzerland, 1975. 60 Use of Models for Water Resources Management, Planning, and Policy the informational needs of an individual user, the The guidance factors are not intended as abso- user is in the best position to determine appropriate lute requirements. Rather, they represent a pre- standards. Guidelines written to deal with a range liminary listing of procedures a manager should of models would likely be either too vague to be consider when undertaking a model development effort. These techniques are meant to provide the potentially useful, or limited in applicability to a manager with an awareness of the total develop- few specific models. In either case, guidelines could ment process—not necessarily to establish a check- inhibit innovative modeling efforts which depart list for compliance. Most of the people we talked from accepted practice. This could inhibit advances to stated that such guidance would be useful if it in the state of the art in modeling research. remained flexible. A further difficulty arises in the use of guidelines Standards developed for use by a single organiza- within an organizational framework. Procedures in- tion are less likely to encounter objections. For extended as general suggestions to guide model ample, the Corps of Engineers has established development and use may tend in practice to be guidelines for models that are incorporated in the used as standards governing modeling activities. A Corps’ Engineering Computer Programs Library. b manager’s natural desire to minimize risk and pre- The stated objectives of the guidelines are to assure clude responsibility for failure could place pressure that models distributed through the library are: on users and developers alike to follow accepted, 1) immediately usable, broad in scope, easy to conventional procedures. In the rapidly advancing modify; 2) consistent with accepted engineering field of modeling, such a bias could conflict strongly principles and practices; 3) uniformly and well with the objective of incorporating the best available documented; and 4) readily understandable by knowledge into current modeling activities. others and easy to set up and apply. A General Accounting Office (GAO) report5 sup- The standards specify the programing language ports the guideline concept, while acknowledging to be used, and suggest specific programing prac- that variations in model development efforts re- tices that will enhance program usability. Detailed quire that guidelines be highly flexible. GAO’s guidelines are provided for preparation of model survey of model developers in the Northwestern documentation. Models that are incorporated in the United States revealed skepticism about guide- library are placed in one of three categories, de- lines—both in general, and in reference to specific pending on the nature of the model and the level GAO proposals: of review it has received. For example, a model in the highest category will have been designed for A primary concern was the fear that the guidance factors could become requirements for all Corps-wide application, and will have received in- modeling efforts. Respondents noted that model dependent review and approval by the Corps’ Of- development efforts are not all the same. They dif- fice of the Chief of Engineers. A further discussion fer in size, complexity, and level of the technology of Corps’ procedures for developing and dissemi- being applied. In addition, the contractual process nating water resource models is included in the as well as the contractual management relation- description of HEC in chapter 4. ship will vary from project to project. Respondents pointed to these structural and management dif- Contractual Mechanisms ferences as evidence of the need for flexibility in implementing any set of guidance factors. More Numerous proposals have emerged for strength- specifically they noted the need to allow the man- ening quality control by requiring the performance ager freedom in determining which factors to con- of certain procedures or the attainment of perform- sider and the level of activity required. ance standards as part of the legal contract for devel- Survey responses prompted GAO to qualify its oping a model. For example, developers might be proposals for modeling guidelines:

6B. Eichert, ‘ ‘Experiences of the Hydrologic Engineering Center in Maintaining Widely Used Hydrologic and Water Resource Com- 5 Wa} ! to Improw ,Management OJ b’edera[~ h’unded Computerized Model~, puter Models, Technical Paper No. 56, Hydrologic Engineering Cen- LT s (;{)vernnlc.nt A(c ounting {)ffi( (,, 1.C;L)-75- 111, 1976. ter, 1978. Ch. 3—General Issues in Model Development, Use, and Dissemination ● 61 — .—— required to provide specific levels of documenta- basis might be impossible. The use of less qualified tion acceptable to a review panel, or to achieve a reviewers for such a panel would reduce the weight specific level of accuracy before final payment on and value of its recommendations. their contracts. Another GAO proposal called for Federal agen- Legal Aspects of Model Use in cy review of contractor performance at the end of Administrative Processes each of five phases in developing models. Both the Models are often used to project the effect of a agency and the developer would have an opportu- proposed administrative action, Managers emplo nity to terminate the development process at the y model forecasts to minimize the possibility of caus- end of each phase: ing costly errors or potential damages associated A contract with a breakpoint at the end of each with inappropriate decisions. Major decisions in- phase should be used so that a developer cannot volving millions of dollars may be based on model- proceed from one phase to the next without writ- generated information. If, for some reason, the ten approval from the user. Each phase or break- models do not accurately simulate real conditions, point should be separately priced so that a termina- administrative decisions based on model results tion at the end of a specific phase will limit the could misdirect regulations, misguide management Government’s liability under the contract to those directives, and misallocate capital investments. costs incurred for the contractor’s performance up to the breakpoint . . . . This gives the manager the Using models in regulatory processes raises the opportunity to stop development if the model is prospect that unforeseen errors may cause adminis- not going to be useful. trative actions to either fall short of their intended

purpose or unreasonably burden those who are reg- Such procedures could increase an organization’s ulated. control over ongoing model development projects, and, if properly managed, could offer incentives Legal issues regarding the use of models in ad- for developers to maintain professional standards ministrative processes have arisen in three areas: and provide adequate user-oriented services. How- 1) standards for Federal judicial review; 2) judicial ever, additional contractual specifications inevitably review of State-level regulations; and 3) use of mod- add to the complexity of monitoring model devel- els for planning and program development. opment. Standards for Federal Judicial Review Peer Review Although judicial consideration of water resource Peer review procedures have been proposed as models dates back to a 1943 Supreme Court case a means of identifying and promoting high-quality involving an interstate dispute over water rights, 7 models without losing the flexibility required for virtually all judicial notice has been in the context innovative modeling. Review panels, composed of of recently promulgated water quality effluent limi- high-caliber professionals who are sensitive to the tations. a Courts have also examined water quality applications for which individual models are de- models that have been used as the basis for analyz- signed, could provide valuable advice to model de- ing an environmental impact statement under the velopers, and assure sponsoring institutions of the National Environmental Protection Act. g value of the models they fund. Opponents of the peer review approach cite the ‘Colorado v. Kansas, 320 U S. 383 ( 1943) 8Assoctatton ojPacJic Ftshenes ~’. E P A , 61.5 F 2d 794 (9th C ir , 1980); bureaucratic burden of establishing and maintain- Kennecott Copper V. E. P A 612 F.2d 1232 (10 Cir. , 1979); I?AS’F Wyan- { ing review policies and procedures, and they ques- dotte Corp v. Cost[e, 598 F 2d 637 (1st Cir, , 1979); ,Vatzonal Crushed Stone Association v. E P A 601 F.2d 111 (4th Cir., 1979); American Zron tion the relative value of the additional informa- and .Steef Instttute v, E P A ( 1 1), 568 F 2d 284 (3rd Cir, , 1977); FMC tion as compared to its probable cost. These oppo- t. 7’razn, 539 h’, 2d 973(4th L’ir. , 1976); API V, L’ P A , 540 F’. 2d 1023 nents also point out that seasoned modeling profes- (lO{h Cir., 1976); A I S 1 \ EPA (1~, 568 F,2ci 284 (3r(i Ctr., 1977), sionals are in relatively short supply—obtainin ‘ohlo Ex t?d Ilrouw L. E P A , 460 F, Supp. 248 (S L) oh,, 1978); g Con~erLatton Counctl oj ,Yrorth Carollna ,, Froehlke, 435 F Supp, 775 their services for a review panel on a continuing (M D N C , 1977), 62 Use of Models for Water Resources Management, Planning, and Policy

Models used for agency rulemaking are adminis- However, the documentation of the model must trative actions reviewable by the courts. 10 The provide an ‘‘adequate explanation’ of the basis for review standard is narrow: the regulation, absent which the court will over- 16 turn the regulation. What constitutes ‘‘sufficient As in other cases involving review of an ad- material upon which to make a reasoned decision, ministrative agency’s rulemaking actions we are governed by an ‘‘abuse of discretion’ standard— though, leaves a great deal of latitude to an Thus, there is a disinclination to ‘‘second in other words, we must not substitute our judg- agency. ment for that of the agency, but must determine guess the agency’s expert determinations as to the whether the administrator’s actions were ‘ ‘ar- model . . . bitrary, capricious, are abuses of discretion, or Federal courts have proved relatively flexible in otherwise not in accordance with law . . . .‘ In order to facilitate meaningful judicial review, we applying the ‘‘reasonable basis’ test to disputed should require administrative agencies to ‘ ‘ar- regulations. In a case where a model simplified the ticulate the standards and principles that govern simulation of complex hydraulic flows in plastic their discretionary decisions in as much detail as manufacturing plants to the degree that the range possible . . . . “11 of flows departed from the model’s results by a factor of 10, the court found no reasonable basis for Most courts reviewing models as a basis for ad- the challenged regulation. In another instance, ministrative decisions rely on the standard set out although the court heard arguments that the chal- in the U.S. Supreme Court case, Citizens to Preserve lenged model process differed from actual opera- Overton Park v. Volpe, 12 that a court reviewing an tion by a factor of 5, it sustained the contested agency’s action should conduct a searching and regulation, being convinced that a reasonable ex- careful inquiry into the facts, but should not planation for the variation existed.20 substitute its judgment for that of the agency. The court held that the agency’s use of the model should The courts’ reluctance to involve themselves in be accorded a ‘ ‘presumption of regularity. “13 evaluating models per se is further illustrated by a case involving proprietary models. In Cleveland This judicial standard has significant implications Electric, which challenged the imposition of a sulfur for an agency’s use of models in regulation, and dioxide control plan based on the use of an EPA grants broad discretion to the agency. When other model, the agency’s model was contested as inferior models have been used to challenge an agency’s to a proprietary model developed by an engineer- model, the courts have examined only whether the ing company. Although expert witnesses testified agency’s model constitutes a ‘‘rational choice. 14 that a superior method of control existed, the com- Although judicial inquiry will include a thorough pany refused to reveal the operating details of its evaluation of a model, it does not extend to the 15 model. As the court saw the problem: determination of the “best possible approach. ’ While such withholding may be both defensi- ble as a matter of law and understandable as a matter of economics, this court cannot consider En- viroplan’s model as available technology until and l’JThe Feder~ Administrative Procedure Act provides that ‘‘except unless it is fully disclosed and evaluated by United to the extent that—( 1 ) statutes preclude judicial review; or (2) agency action is committed to agency discretion by law, 5 U. SC. sec. States E.P.A. —the agency charged by Congress zz 701 (a) ( 1976), ‘ ‘final agency action for which there is no other ade- with making these decisions. quate remedy in a court (is) subject to judicial review. 5 U. S.C. sec. 704( 1976). For a discussion, see, D. P, Currie, ‘ ‘Judicial Re- view Under Federal Potlution Laws, 62 Iowa Law Review 1221 ( 1977).

11A. 1. S. 1. V. E P A. (1), 526 F. 2d 1027 (3d C ir., 1975). lZC1t1zen5 to prt-sovt ouerton park, Inc v. Volpe, 401 U.S. 402 416 ~6Kmneco~t COO/MT V. E. p. A , 612 F.2d 1232, 1240 (lOth Cir,, 1979). (1971). ~~A150ciation oJPul@ Fishmtes v. E. P.A , 615 F. 2d 794, 803 (9th Cir., Isol,flton Park, 401 U.S. at 415. 1980). 14Cleve]and E]ec[r;c I]fuminating CO. V. E. P. A., 5~’2 F.zd 1150, lapacl~ic Ftsheries, 615 F. 2d at 810. 1161 (6th Cir., 1978), cert. denied, 439 U.S. 910 (1978); U.S. Steel t9FA~C coTp, v, Train, 539 F, 2d 973, 980 (qth C ir. , 1976). Corp. v. E. P. A., 605 F.2d 283, 292 (7th Cir., 1979). zopacl~lc F1fhU1e5, 615 F. 2d at 810, 814. 1 BCleLle[and Electric, 572 F. 2d at 1150, 116 1; see also, b’ermont Yankee 21572 F,2d at 1163. A’uclear Power Corp v. NRDC, 435 U.S. 519, 549 ( 1977). ‘z Ibid, Ch. 3—General Issues in Model Development, Use, and Dissemination ● 63

Judicial Review of State-Level Regulations Use of Models for Planning and Program Development Relatively few legal controversies have arisen over use of models by a State government as a basis Probably in no other area is the use of models for decisionmaking. The lack of reported cases may more prevalent than in planning and program de- be partly attributable to a general lack of model use velopment. However, errors in planning programs by States for regulatory purposes. Another reason which are based solely on analysis by models can may be the close link between Federal and State be perpetuated in decisions made on the basis of programs —such conflicts may arise in the context such plans. Mandated ‘‘consistency’ requirements of the applicable Federal programs. are potentially a major avenue for institutionaliz- ing this kind of error. States have occasionally used models as evidence in administrative proceedings to determine whether For example, the Clean Water Act requires that a violation of an environmental control law has oc- the National Pollution Discharge Elimination curred; this is particularly true in the area of air System permits issued for point sources of pollu- pollution control .23 For instance, the Illinois Pollu- tion must not conflict with an approved section 208 tion Control Board applied a ‘‘general theoretical areawide management plan.28 In this manner, Con- formula” to the processing data of a smelting com- gress established a ‘‘consistent’ planning system, pany to find the company in violation of air pollu- linking different elements to areawide planning tion standards, However, upon review, an Illinois under section 208. Consistency requirements also court held that such modeling evidence was insuf- extend to construction of publicly owned treatment ficient to support the board’s determination.24 facilities, which must conform with the approved section 208 plan to be accepted.2g Section 208 plans Litigation over regulations predicated on infor- depend heavily on modeling. This statutory linkage mation from a ground water model occurred in the between the areawide planning programs and reg- State of Washington in 1975. The State had devel- ulation or construction activities raises the ques- oped a computer model for defining maximum rates tion of whether unforeseen modeling errors in plans of withdrawal and issuing new rights to ground may cause significant problems during implemen- waters. For the Odessa area, which had been de- tation, and subsequently lead to litigation. clared a critical ground water region, the State issued regulations to establish ceilings on withdraw- An important corollary to this issue is the ques- als with the assistance of the developed models. 25 tion of a modeler’s liability for the effects of in- Affected ground water users disputed the accuracy accurate model results. No ruling yet exists on of the model results;26 however, the courts upheld whether model use involves an express or implied the regulation. Subsequent corrections to the model guarantee that the operation of a system will sub- have altered model results, though not to the degree stantially conform to model-generated information. of affecting the regulation’s efficacy in the eyes of If an individual or organization is placed in the posi- State officials. Nonetheless, no further challenges tion of certifying compliance with regulatory stand- to the regulation have been offered .27 ards based on model results, whose responsibility is any subsequent nonattainment of such standards?

23 Absent any definitive ruling on the issue, new For a discussion, see, R. A. Brazcuer, “Air Pollution Control; Sufficiency of Evidence of Violatlon in Administrative Proceedings regulatory programs involving modeling and the Terminating in Abatement Orders, ” 48 A L R 3d 795 use of highly sophisticated modeling analysis may ~~.4[[ted Me[a[ C. v I[[lnou Po[[utton Control Board, 22 I ~ ~ APP. 3d increase the liability of the design professional. Sim- 823,318 N E.2 257, 264 (1974).

Z5G. E, .Maddox, et d., ‘‘,Management of Groundwater in Eastern ilar problems have arisen over the professional lia- 1+’ashington, Engineering, Geology, and Soils Symposium, 13th An- bilities of technically trained staff in other fields. nual Proceedings, University of Idaho, Moscow, Apr. 2-4, 1975, p. The modeling community has already indicated its 201, published by Idaho Transportation Department, Division of Highways, Boise, 1975. concern over exposure to liability in the context of ZbConversation with Alan Wald, Hydrologist, Washington Depm- ment of Ecology. *pConversation with Charles Roe, Senior Assistant Attorney Gen- Zsclean water Act, sec. 208(e), 33 U. SC. sec. 1288(e). eral, Washington Department of Ecology. ZgC]ean Water Act, sec. 208(d), 33 U. S.C. sec. 1288(d). 64 . Use of Models for Water Resources Management, Planning, and Policy certifying compliance with building energy per- Increased use of complex modeling systems, and formance standards under the Energy Conserva- layered model use to develop State ‘ ‘equivalent’ tion Standards for New Buildings Act of 1976.30 standards or programs under Federal mandates, may compound initially acceptable modeling errors, 30Milt I.unch, “DOE’s New BEPS Pose Many Legal, Liability Questions for Design Professionals, ” Engineering Times, April 1980; and also increase a modeler’s potential liability. Statement of E. K. Riddick for the National Society of Professional Engineers on the Proposed Building Energy Performance Standards, Mar. 24, 1980, pp. 14-16. 3 I Testimony of D, carter for the American Consult Ing F.ngineers Council, hearings before the Senate Governmental Al’fairs Commit- tee, Nov. 20, 1979, p. 167. Chapter 4 Federal Use and Support of Water Resource Models .

Contents

Page Analysis of Current Federal Modeling Capabilities ...... 67 Methods Used to Survey and Analyze Federal Model Use...... 67 Findings From the Federal Agency Survey ...... 70 Findings From the Federal Workshop ...... 72 Current Approaches to Federal Model Management ...... 76 Consideration of Models in Governmentwide Water R&D Policies ...... 77 Existing Governmentwide Mechanisms for Coordinating Modeling and Model-Related Information ...... 80 Existing Support Structures for Agency-Level Modeling Activities ...... 84 Agency-Level Mechanisms for Providing Information on and Access to Existing Models ...... 88

TABLES Table No. Page 3. Federal Model Use by Program ...... 68 4. Agency Estimates of Fiscal Year 1979 Expenditures for Water Resource Models and Related Activities ...... 70 Chapter 4 Federal Use and Support of Water Resource Models

The Federal Government has a very broad range These responsibilities are expressed in numerous of water resource responsibilities. It is a major in- laws, and are administered by an array of Federal vestor in facilities to control water supplies and treat departments, agencies, and regulatory authorities. polluted waters. It has taken the lead in programs Water resource concerns touch virtually every as- to bring additional supplies to water-short areas of pect of the Nation’s economic, social, and political the country, and more recently to encourage more well-being; thus, they are an integral part of the cost-effective approaches to water use in these areas. missions of many governmental institutions. It has provided the legal and institutional frame- In analyzing Federal use of water resource mod- work within which States work to set water qual- els, the Office of Technology Assessment (OTA) ity standards and ensure that they are met. More- collected and evaluated information from over 20 over, it is responsible for managing the water that agencies and agency offices. Model use was exam- flows through the 776 million acres of the country ined by agency, by authorizing legislation, by re- directly under Federal jurisdiction. source issue, and by professional discipline.

ANALYSIS OF CURRENT FEDERAL MODELING CAPABILITIES

Methods Used to Survey and model-related concerns. Major findings from the Analyze Federal Model Use workshop are summarized below; a more extensive summary of the Federal workshop, and of a subse- OTA used two primary approaches in soliciting quent workshop held for modelers from universities information on Federal modeling efforts. It initially and the private sector, is presented in appendix A. held a 2-day workshop for Federal modelers dur- The second major component of OTA’s informa- ing October 1979, to determine their views on cur- tion-gathering activity was a survey of the 22 Fed- rent major problems in Federal water resource eral entities with substantive water resource respon- modeling efforts. Attended by representatives from sibilities, conducted in June 1980. Each agency or 21 Federal organizations, the workshop revealed office was requested to provide information on its significant institutional constraints to effective model use under more than 20 major pieces of model development and use. In preparation for the water resource legislation. Respondents were asked workshops, each agency represented was requested to specify legislatively assigned responsibilities, and to provide written responses to questions regarding areas in which models are employed, according to its current use and development of models; critical eight general use categories: 1 ) program planning; problem areas, appropriate roles, and reasons for 2) promulgating regulations; 3) enforcing regula- using models; anticipated future modeling needs; tions; 4) complying with regulations; 5) planning and current levels of monetary and personnel re- or evaluating projects; 6) allocating funds; 7) tech- sources devoted to modeling. nology transfer; and 8) operations and manage- At the workshop, modelers met in groups accord- ment. Statistical results of this survey are tabulated ing to areas of professional expertise. Each group in table 3. Detailed descriptions of each agency’s listed, discussed, and ranked the importance of its model use under specific laws and programs are

67 68 . Use of Models for Water Resources Management, Planning, and policy

Table 3.—Federal Model Use by Program

Number of agencies Agencies using Number of agencies using models to models to meet with program meet program program Section involvement responsibilities responsibilities Federal Water Pollution Control Act Amendments of 1972 (as amended by the Clean Water Act of 1977) Grants for pollution control program...... 106 2 0 Mine water pollution control programs...... 107 2 2 FS, BM Grants for construction of treatment works...... 201 5 4 ESCS, CORPS, USGS, EPA-OWRS Areawide waste treatment management...... 208 7 6 EPA-OWRS, BR, FS, ESCS, SEA Basin planning...... 209 9 7 BR, FS, EPA-OWRS, ESCS, NOAA, WRC, USGS Water quality waivers...... 301 2 2 EPA-OWE, NOAA Water quality-related effluent limitations...... 302 4 1 EPA-OWRS Water quality standards and implementation plans...... 303 6 4 BR,FS, NOAA, EPA-SWER Toxic and pretreatment effluent standards...... 307 8 2 EPA-OWRS, NOAA Oil and hazardous substances liability...... 311 4 1 USGS Clean lakes...... 314 6 3 FS, NOAA, USGS Thermal discharges and exemptions...... 316 3 2 USGS, EPA-OWE Guidelines and permits for dredged or fill material...... 404 7 1 USGS Disposal of sewage sludge...... 405 7 1 ESCS Safe Drinking Act Determining adverse health effects...... 1412 1 1 EPA-DW Protection of underground sources of drinking water...... 1421 8 3 USGS, MINES, EPA-DW Protection of sole-source aquifer systems...... 1424 1 1 EPA-DW Surface impoundment assessment. 1442 1 1 EPA-DW State program grants...... 1443 1 1 EPA-DW Special study and demonstration project grants...... 1444 5 1 USGS Toxic Substances Control Act Testing of chemical substances and mixtures...... 4 4 1 EPA-PTS Regulation of hazardous chemicals and mixtures...... 6 5 1 EPA-PTS Resource Conservation and Recovery Act Solid waste management guidelines 1008 4 1 USGS Identification and listing of hazardous wastes...... 3001 4 0 Standards for owners and operators of hazardous waste treatment, storage, and disposal facilities. . . 3004 7 0 Consolidated permits for hazardous waste management facilities. . . . . 3005 5 0 Ch. 4—Federal Use and Support of Water Resource Models 69

Table 3.-Federal Model Use by Program (Continued)

Number of agencies Agencies using Number of agencies using models to models to meet with program meet program program Section involvement responsibilities responsibilities Grants for State resource recovery and conservation plans...... 4008 1 0 Full-scale demonstration facilities grants ...... 8004 1 0 Resource recovery system and improved solid waste...... 8006 3 1 USGS Endangered Species Act Minimizations of impacts of Federal activities modifying critical habitats...... 7 9 3 BR, FS, FWS Surface Mining Control and Reclamation Act Surface coal mine reclamation permitting...... 506 6 3 FS, USGS, OSM Permit approval or denial...... 510 1 1 OSM Environmental protection performance standards for surface coal mine reclamation. . . 515 6 4 FS, USGS, BM, OSM Soil and Water Resource Conservation Act of 1977 Data collection about soil, water, and related resources...... 5 6 2 FS, USGS Soil and water conservation programs...... 6 7 5 FS, ESCS, NOAA USGS, BM Water Resources Planning Act Regional or river basin plans and programs and their relation to larger requirements...... 102 10 7 BM, BR, ESCS, CORPS, NOAA, Coordinating Federal water and USGS, WRC related land resources programs and policies...... 102 7 2 USGS, BM Assessemnt of the Nation’s water resources conditions...... 102 1 1 WRC Coastal Zone Management Act State coastal zone land and water resources management program development and management grants...... 305 6 2 NOAA, USGS Executive Order 11988 Flood plain management...... 2&3 9 5 FS, CORPS, USGS, WRC, NRC Flood Control Act of 1936 and Amendments Flood control structures...... 1,2,3, 7 5 BR, FS, CORPS, NOAA, USGS National Flood Insurance Act of 1968 Identification of flood-prone areas. . 1360 2 2 FEMA, SCS Federal Reclamation Act of 1902 and Amendments Irrigation distribution systems. . . . . (43U.S.C.421) 5 3 USGS, FS, BR Construction of small projects. . . . . (43U.S.C.422) 3 1 FWS National Environmental Policy Act Administration; EIS review and comment...... 102,103 5 5 BR, FS, CORPS, NOAA, NRC 70 ● use of Mode/s for Water Resources Management, planning, and policy

Table 3.–Federal Model Use by Program (Continued)

Number of agencies Agencies using Number of agencies using models to models to meet with program meet program program Section involvement responsibilities responsibilities

Atomic Energy Acf of 1954 Flood protection of nuclear facilities...... 10 CFR 50 1 1 NRC Water supply for nuclear power facilities...... 10 CFR 50 1 1 NRC Limitation of radioactive liquid to ground and surface water...... 10 CFR 20, 50, 61 2 2 NRC, USGS Fish and Wildlife Coordination Act Consultation and provision of recommendations; surveys and investigations...... 182 2 2 FWS, NOAA Colorado River Basin Salinity Control Program...... 10, 201, 202, 203 2 2 BR, SCS Agency abbreviation key:

ASCS — Agricultural Stabilization and Conservation Service ESCS — Economics and Statistics Cooperative Service CORPS – Army Corps of Engineers FEMA — Federal Emergency Management Agency BM – Bureau of Mines FS — Forest Service BR – Bureau of Reclamation FWS — Fish and Wildlife Service DOE – Department of Energy NOAA — National Oceanic and Atmospheric Administration EPA – Environmental Protection Agency NRC — Nuclear Regulatory Commission DW – Office of Drinking Water OSM — Office of Surface Mining Reclamation and Enforcement OWE – Office of Water Enforcement Scs — Soil Consewation Service OWRS – Office of Water Regulations and Standards SEA — Science and Education Administration SWER – Solid Waste and Emergency Response Program USGS — U.S. Geological Survey PTS — Pesticides and Toxic Substances Program WRC — Water Resources Council provided in appendix B. Insofar as OTA has been Table 4.—Agency Estimates of Fiscal Year 1979 able to ascertain, no previous governmentwide Expenditures for Water Resource Models and compendium of water resource model use and ap- Related Activities (in millions of dollars) plication has been attempted. U.S. Geological Survey: Research...... 3.0–4.0 These information-gathering activities were sup- Application...... 12.0—15.0 plemented by OTA-commissioned reports on Army Corps of Engineers...... 6.5—7.7 model uses, limitations, and appropriate roles in National Science Foundation...... 2.8 National Oceanic and four broad water resource areas, and by telephone Atmospheric Administration...... 2.8 surveys regarding costs associated with modeling Department of Energy...... 0.9–1 .1 activities for fiscal year 1979. Estimates of fiscal year Department of Agriculture...... o.7a Department of Interior...... 4.7—5.9 1979 expenditures for water resource models are Environmental Protection Agency...... 7.8—9.4 provided in table 4. OTA has also relied on previ- Total...... 40.2—49.4 ously published studies of Federal, Canadian, and alncludes estimates only from SCS and ESCS. international model use to corroborate its general SOURCE: Developed from information provided in agency responses to OTA questions regarding model use, October 1979, and from a June 1979 findings. Five of the most relevant studies are sum- telephone survey of selected Federal agencies. Figures include expend- marized in appendix C; individual references to itures for both research and application. these findings are also made throughout this chapter. general indication of current patterns of Federal water resource activities and model use. As might Findings From the be expected, the more comprehensive the scope of Federal Agency Survey a water resource-related law, the greater the number of agencies whose missions are affected by it. Table 3, which summarizes agency model use The widest-ranging of current water resource laws, by law, and compares areas of responsibility to the Clean Water Act of 1977, involves about 15 areas in which models are employed, provides a agencies and offices, which are assigned various Ch. 4—Federal Use and Support of Water Resource Models ● 71 responsibilities under or must comply with regulation are routinely carried out with models. Under tions stemming from 14 different sections of the law. the Forest and Rangeland Renewable Resources Twelve agencies or offices indicated model use Act of 1974 (Public Law 93-378), for example, the under this act. Some laws, such as the National Forest Service of the U.S. Department of Agricul- Flood Insurance Act of 1968 (Public Law 90-448), ture (USDA) is charged with developing and imple- are the responsibility of a single agency—in this menting long-range land and resource management case, the Federal Emergency Management Agen- plans for the federally owned forests under its juris- cy. On the whole, however, most pieces of Federal diction. It uses models that assess the effects of dif- legislation affect more than a single agency, office, ferent management practices on water supply, or regulatory authority. water quality, other significant natural resources, and local economic activity. The information generated by these models is used in determining Na- None of the laws identified in the Federal agen- tional Forest Management Act Regulations. cy survey specifically require the use of models to analyze a water resource issue. However, many of Much of the current Federal legislation directs the analytic responsibilities specified in the legisla- individual agencies to determine standards that may 72 . use of Mode/s for Water Resources Management, Planning, and policy

affect the program responsibilities of other agen- been developed elsewhere in the Federal Govern- cies. Under the Clean Water Act (Public Law ment. When practicable, model adaptation permits 95-21 7), the Safe Drinking Water Act (Public Law significant cost-savings, although adequate data 93-523), and the Toxic Substances Control Act bases and computer facilities, in addition to tech- (Public Law 94-469), the Environmental Protec- nical assistance in adapting the model, are still nection Agency (EPA) regulates and sets allowable con- essary, However, information about the availability centrations for a number of toxic substances, organ- of many existing Federal models is not readily ob- ic chemicals, pesticides, and other residuals. A vari- tainable. Few agencies have taken steps to dissemi- ety of models are used to determine how these sub- nate information on the models they have devel- stances are transported to and within receiving oped. In addition, Federal models are often so poor- waters, and to estimate their effects on human and ly documented that a manager cannot determine aquatic populations. Such regulations must subse- their suitability for use by his agency. quently be incorporated into analyses performed by various agencies of USDA and the Bureau of Mines, land and forest management practices of Findings From the Federal Workshop the Department of the Interior (DOI) and the Although Federal agency modelers met and dis- Forest Service, and permitting processes of the cussed issues in four separate professional group- Nuclear Regulatory Commission for thermal ef- ings—l) surface water flow and supply; 2) surface fluents, among others. water quality; 3) ground water; and 4) economic/ The findings outlined in table 3 reflect a highly social-the majority of their concerns were not spe- uneven pat tern of Federal model use for water re- cific to these areas, but encompassed the broader source analysis. While some agencies use models problem of providing adequate and appropriate in- to analyze a particular resource issue throughout stitutional support for modeling activities in the range of their statutorily assigned program general. Indepth summaries of modelers’ delibera- responsibilities, others use them only for a particu tions on such issues as research and development lar responsibility (e.g., complying with regulations), (R&D) needs, data needs, documentation, valida- and still others rely solely on noncomputerized ana- tion, technology transfer, model maintenance, the lytical approaches. These inconsistencies cause such utility of model clearinghouses, and interagency problems as inconsistent flood plain delineations by coordination, are provided in appendix A. different agencies, confusion over best management Participants ranked the following issues as being practices for controlling nonpoint source pollution, among the most significant of those discussed: and disputes over projections of the amount of water available for energy development in the West- ● collecting accurate and adequate data to ern United States. Further, while highly efficient develop, test, and apply models; model-based management techniques have been de- improving decisionmaker understanding 01 veloped in several Federal agencies (e. g,, for operat- general capabilities and limitations of models; ing reservoirs), many agencies do not benefit from ● improvements in user support, training in this already-developed expertise. model use, and analysis of results; A number of factors underlie agency decisions ● greater emphasis on documentation of models; regarding model use. Developing a model is an ex- ● improved planning and resources for model pensive and technically complex undertaking, in- maintenance and management; volving highly specialized personnel requirements, ● making federally developed models known and extensive computer facilities, and appropriate data available to other Federal agencies and to the bases. If the problem to be analyzed is not directly public; and related to the agency’s mission, the agency will ● improving coordination among agencies for often be reluctant to commit the resources necessary model development and use. to develop a model to address the problem. The significance of these issues to water resource Moreover, substantial difficulties often deter analysis and problem-solving capabilities at the Fed- agencies from adapting models that have already eral level is discussed below. Ch. 4—Federal Use and Support of Water Resource Models 73

Data Availability The availability of sufficient data to characterize a physical system is critical to modeling it successfully. Computer models are often highly data intensive, requiring independent data sets for development, calibration, verification, and application phases. Workshop participants pointed to the expense of collecting water resource data as a major limiting factor in constructing models. Most existing Federal data bases are created to serve program purposes rather than for research and analysis per se. Developers consequently find much of the existing data unsuitable for modeling activities. Participants suggested coordinated approaches to data collection and model development, as well as sensitizing model developers to the potential data requirements (and costs) of their models. Emphasis was also placed on the need to improve access to existing data bases, and improve the cost effectiveness of future data collection efforts, particularly through interagency coordination and data base consolidation. Coordinating and integrating data collection on a governmentwide basis is a major Federal management issue, and concerns many informational purposes in addition to modeling efforts. Consequently, an indepth analysis of Federal data-gathering activities is beyond the scope of this report. However, results from the OTA workshop and surveys, as well as surveys of federally developed models by the National Science Foundation (NSF)l and the General Accounting Office (GAO),2 indicate that minimize additional data-gathering costs associated modelers and managers alike consider problems in with future modeling efforts. obtaining data to be the most prevalent limitation on model development efforts. Three of the four Improving Decisionmaker OTA workshop groups considered this to be their Understanding of Models top priority concern, while respondents to the GAO Information gaps between decisionmakers and survey attributed one-fifth of all identified model- modelers were among the top three priorit con- ing problems to data availability. Any future at- y cerns for all four modeling groups at the OTA Fed- tempts to improve Federal data-gathering practices eral workshop. Workshop participants focused on and procedures will have major effects on the mod- the relationship between modeling and the decision- eling community. Input from this community making process as a major deficienc in current should be solicited in data collection planning to y Federal modeling practices. Upper-level managers

‘Gary Fmmm, William L. Hamilton, and Diane E. Hamilton, Fed- were characterized as being unaware of basic mod- erally Supported Mathematical Models Survey and A nalysls, under contract eling concepts and of the limitations and capabilities with the Division of Social Systems and Human Resources of the Na- of the specific models they use. Modelers pointed tional Science Foundation, June 1974. 2 Ways to Improue Management oj Federally Funded Computerized Models, to a lack of mechanisms throughout the Federal General Accounting Office, August 1976. Government for bringing managers and modelers 74 ● Use of Mode/s for water Resources Management, Planning, and policy together to plan and develop models. Such a lack result, and are quickly abandoned to agency ar- of interaction was seen as a major contributor to chives. management-level mistrust of models, and the inadequacy of current levels of support for planning User Support long-range model development, documenting and Participants in the OTA modeling workshop fre- maintaining models, and providing user services. quently asserted that Federal modeling efforts have These findings are strongly in accord with those overconcentrated on model development, and de- from earlier studies. The survey of 222 nondefense voted inadequate resources to transferring model- Federal models conducted in 1974 for NSF found ing technology and expertise to potential users. All highest rates of failure in modeling projects designed four workshop groups placed some aspect of user to provide information to policy makers. The low services among their top three priorities. Many par- utilization rate of such models was attributed pri- ticipants stated, however, that current agency ca- marily to lack of communication between model reer evaluation systems discourage modelers from builders and potential policy makers during model providing such technology transfer to model users. development, and secondarily to policymakers’ lim- While incentives are provided for developing in- ited understanding of models that had already been creasingly sophisticated models, no incentive struc- developed. 3 Similarly, one-fifth of modeling prob- ture currently encourages modelers to aid users in lems identified in the GAO survey (1976) were at- understanding, running, and interpreting the re- tributed to ‘‘lack of management acceptance and sults of such tools. knowledge of modeling techniques.”4 Workshop participants singled out three major Integrating the needs of decisionmakers into aspects of technology transfer as needing additional model development processes is especially critical attention and resources: 1 ) documentation; 2) train- if models are to be used effectively at agency deci- ing in model use and interpretation; and 3) techni- sionmaking levels. Federal managerial personnel cal assistance. Most participants appeared to con- often have a great deal of discretion over what pro- sider documentation the most critical of technology cedures to employ in analyzing an issue. Some may transfer needs. Because documentation is time con- have obtained favorable results from modeling in suming and expensive to produce, decisionmakers the past, while others may have been ‘‘burnt’ by and modelers alike have tended to assign it low pri- relying on the accuracy of model-based informa- ority, concentrating on the production of ‘bottom- tion. Since the Federal Government provides no line’ information. Without adequate documenta- guidelines regarding model uses for analytical pur- tion, however, decisionmakers cannot subsequently poses, and offers very little management-level determine how the information was generated, nor education in model use and interpretation, deci- evaluate it. Documentation is also crucial for pro- sionmakers are generally ‘ ‘on their own’ in viding individuals in other Federal agencies a means deciding when to commit their agencies to model- of determining whether they can use a previously ing efforts. developed model. A 1974 GAO survey of 710 Fed- eral data-processing personnel and auditors who In practice, Federal agencies tend to commission reported problems due to inadequate documenta- models in response to a specific problem, when a tion, revealed that nearly one-third (233) of the decisionmaker becomes aware of the need for other- related programs had to be totally rewritten, and wise unavailable information. All too frequently, one-sixth (1 27) of the automated data-processing however, Federal modelers are given little instruc- systems had to be redesigned. Moreover, more than tion regarding the nature of the desired informa- half (428) of the documentation-related problems tion, and are not provided access to the individual(s) resulted in substantial delays in the completion of who must act on the information generated. Tech- 5 assignments. nically sophisticated, yet impractical models often

3Fromm, Hamilton, and Hamilton, op. cit., pp. 3-7, 51-54 51mprowrmmt .Vee&d m Documenting Computer [email protected], General Account- ‘General Accounting Office ( 1976), op. cit. , p, 37. ing Office, October 1974, pp. 6-7. Ch. 4—Federal Use and Support of Water Resource Models ● 75

Concern over the inadequacy of current levels Maintenance and Dissemination of documentation for Federal models is corrobo- The current structure of Federal modeling activ- rated by the 1974 NSF survey, and by a 1979 sur- ities gives agencies little incentive to consider poten- vey of 39 modelers conducted for the National tial uses for models once they have served the agen- Bureau of Standards (NBS). NSF found that for cy’s primary purpose. Consequently, most models about 75 percent of the 222 surveyed models, the are not updated, or maintained, to keep them tech- documentation supplied by the developer was in- nologically current, nor is information about their adequate to enable nonproject personnel to set up existence or availability circulated among poten- and run the model. G Developers surveyed by NBS tial users in government and the private sector. One showed strong support for governmentwide model of the most frequently voiced concerns of workshop documentation guidelines, including the specifica- participants was the difficulty of locating and ob- tion of a documentation plan in model development taining existing Federal models. Many modelers contracts, detailing the documents to be produced, considered improving access to current models a the resources allocated, and personnel responsibil- 7 higher priority than improving and developing new ities. ones. Participants generally agreed that lack of in- Training opportunities are essential to developing formation regarding the availability of Federal mod- in-house capabilities for running and interpreting els is a significant barrier to their widespread use. models. Unless training is supplied, agencies are totally dependent on model developers for model- Participants also noted the Federal Government generated information. The 1974 GAO survey lack of commitment to maintaining the models it found the third-largest source of major modeling has already developed. They stressed the need to problems to be “lack of qualified personnel to develop mechanisms and/or organizational units operate and maintain the model. Workshop par- with routine responsibilities for periodic model ticipants were similarly concerned to find ways of analysis and updating. The need to inform model encouraging agencies to provide adequate resources users of changes made to a model was also consid- for model-related training, Different levels of train- ered to be neglected in current agency procedures. ing for decisionmakers and for users were repeatedly advocated, the latter type to incorporate “hands- Interagency Coordination on ‘‘ interaction with the model and ‘ ‘one-on-one’ Federal modelers identified the lack of interagen- instruction where possible. cy coordination as a major bottleneck in efforts to Workshop participants also pointed to the routine advance the state of the modeling art. Managers provision of technical assistance as an inexpensive tend to be unaware of the modeling and model de- means of troubleshooting in model use, The avail- velopment projects being supported by other agen- ability of knowledgeable individuals to answer sim- cies, a situation that may lead to decisions to build ple ‘ ‘over-the-phone’ questions can save man- models already in existence or in process of develop- hours and computer time that are otherwise lost ment. A certain amount of duplication in model- to trial-and-error attempts to operate the model. ing has potentially beneficial effects—it fosters a For more complex models and/or modeling prob- kind of competition from which more accurate and lems, participants suggested temporarily assigning efficient modeling techniques can result. However, developers to user organizations to facilitate the ini- for highly complex modeling tasks, interagency tial setting-up of the model. pooling of resources and technical expertise could facilitate greater and more rapid advances than are possible when each agency functions independently. bFromm, Hamilton, and Hamilton, op. cit. , p. 6. As explained in a USDA Soil Conservation Serv- ‘Saul I Gass, ‘ ‘Assessing Ways to Improve the Utility of Large- ice background paper for the OTA modeling work- Scale Models, ‘‘ in Valldutlon and Assessment Zssues of Ener~ Models, ~’a - tional Bureau of Standards, Special Publication 569, February 1980, shops, “There would be value in encouraging p, 251. broader use of certain water resource models among 76 ● Use of Mode/s for water Resources Management, Planning, and policy

Photo credit: @ Ted Spiegel, 1982 Federal agencies with modeling expertise and computing facilities provide extensive assistance to State and local users, as well as to users in other Federal offices. Miniature lights on these panels at USGS computer facilities in Reston, Va., glow when telephone hookup lines to computers are currently in use

Federal agencies both to reduce duplication of mod- only means of assuring that high-quality models are cling effort and to obtain the benefit of multiple brought to completion. The creation of adequate agency comment following their use. data bases to support sophisticated modeling proj - ects, in particular, calls for interagency coordina- Further, for highly complex and interdisciplinary tion and planning. modeling, interagency participation may be the

CURRENT APPROACHES TO FEDERAL MODEL MANAGEMENT

This section reviews the Federal legislation and arrangements currently responsible for disseminat- program activities that affect the development and ing water resource models and/or assisting other use of water resource models. It analyzes the plan- water resource agencies to use them. Because mod- ning framework through which funding is provided cling is an integral part of Federal responsibilities for model-related work. This section further defer water resource analysis, data collection, and scribes the major organizational and institutional R&D, this section also addresses a number of Fed- Ch. 4—Federal Use and Support of Water Resource Models ● 77 eral agencies and offices for which the advancement Develop a five-year water resources research of modeling capabilities is not a primary objective. program in cooperation with the (state water re- The section is organized according to four major search) institutes and appropriate water entities, areas of Federal involvement: 1 ) governmentwide indicating goals, objectives, priorities, and funding water R&D policies; 2) governmentwide coordina- requirements (sec. 103 (b)). tion and dissemination activities; 3) agency-level modeling activities; and 4) agency-level dissemina- To fulfill these objectives, and other objectives of tion activities. the act:

Consideration of Models in The Secretary shall cooperate fully with, and shall obtain the continuing advice and cooperation Governmentwide Water R&D Policies of, all agencies of the Federal Government con- The Water Research and Development Act cerned with water problems, State and local governments, and private institutions and individuals, of 1978 to assure that the programs conducted under this The Water Research and Development Act of Act will supplement and not duplicate other water 1978 is currently the major legislative mechanism research and technology programs, will stimulate for coordinating the development of analytical tools research and development in neglected areas, and will provide a comprehensive, nationwide program to address water resource issues. It states the con- of water resources research and development (sec. gressional finding that ‘‘the Nation’s capabilities 406 (a)). for technological assessment and planning and for policy formulation for water resources must be In assigning responsibility for developin a com- strengthened at both the Federal and State levels, g and assigns responsibilities to the President and the prehensive 5-year water resources research program to the Secretary of the Interior, the act broadl Secretary of the Interior for developing a coordi- y nated Federal program of water-related research outlined a new mechanism for coordinating Federal and technology. water resources analysis. Between 1963 and 1977, such a task had been the responsibility of the Com- The act directs the President to: mittee on Water Resources Research (COWRR), Clarify agency responsibilities for Federal water under the aegis of the Federal Council for Science resources research and development and provide and Technology within the Executive Office of the for interagency coordination of such research, in- President (EOP). Beginning in 1966, COWRR de- cluding the research authorized by this Act. Such veloped and annually updated a long-term program coordination shall include: 1 ) continuing review for water resources research. Its reports recom- of the adequacy of the Government-wide program mended priority research areas and were intended in water resources research and development and to guide Federal agencies in allocating research identification of technical needs in various water funds. resources research categories, 2) identification and elimination of duplication and overlaps between two or more programs, 3) recommendations with The 1978 act calls, in general terms, for EOP respect to allocation of technical efforts among the to play a lead role in coordinating the conduct of Federal agencies, 4) review of technical manpower water resources analysis among the Federal agen- needs and findings concerning the technical man- cies, relying on DOI to develop a research and tech power base of the program, 5) recommendations nology agenda as a basis for EOP decisions. Presi- concerning management policies to improve the dent Carter’s message on science and technology, quality of the Government-wide research effort, delivered to the Congress on March 27, 1979, fur- and 6) actions to facilitate interagency communica- ther directed the Secretary of the Interior and the tion at management levels (sec. 406(b)). Director of the Office of Science and Technology In addition, the act assigns specific responsibility Policy (OSTP) to determine research priorities for to the Secretary of the Interior to: meeting the Nation’s long-range water needs. 78 ● Use of Models for Water Resources Management, planning, and policy

Development of the Five-Year Water Agencies also report needs for information and Resources Research Program models in areas where, lacking authorization to fund model development, they must rely on the Under the joint direction of DOI and OSTP, in- modeling effort of other agencies. The Soil Con- teragency policy and working groups summarized servation Service of USDA pointed out the need current agency-level programs of water reseach and ‘ ‘to improve estimates of erosion potential and short-term priorities in ‘‘Water Research Priorities 8 nutrient loss from forest and rangelands; similarly, for the 1980’s” (April 1979), and developed rec- the Department of Transportation stated that it ommendations for improving the Federal effort in could benefit from work to “develop operational 10 broad subject areas in ‘ ‘Interim Report—Pri- two-dimensional model simulating stream degrada- orities in Federal Water Resources Research’ tions, aggravation, and local erosional processes. (August 1979).9 Both documents are compendiums of individual “Proposed U.S. National Water Resources Re- agency research plans; consequently, opportunities search, Development, Demonstration, and Tech- for interagency coordination of modeling efforts, nology Transfer Program, 1982-87, draft, an ex- or other research and technology-related activities, panded version of the agency summaries with pro- are not addressed. In addition, neither document jected funding levels for fiscal years 1982 to 1987, describes agency activities in sufficient detail to per- was delivered to the Water Resources Research Re- mit a determination of levels of funding allocated view Committee of the National Academy of Sci- to modeling activities, or the means used to coordi- ences (NAS) for review in December 1980. The nate modeling and related support efforts within NAS evaluation, Federal Water Resource.s Research: A each agency. No summary of State needs was in- Review of the Proposed Five- Year Program Plan, was cluded in either document, and it is difficult to published in May 1981. determine how or whether the State water resources Water resources models figure prominently in research institutes’ 5-year programs were con- the description of agency research efforts in the sidered in formulating the agency research plans April 1979 and December 1980 documents. The that constitute the December 1980 draft. extent of the Federal commitment to modeling ac- The ‘ ‘Interim Report’ of September 1979 sets tivities is exemplified by frequently occurring refer- out goals and general priorities for governmentwide ences to them in many of the agency reports. EPA, water resources R&D. It indicates many areas in for example, lists among its research priorities the which improved modeling capabilities are needed, need to: including conjunctive ground water/surface water . . . develop, test and validate models for simulat- systems, aquatic ecosystems, environmental im- ing source loads and ‘‘ in-stream’ processes for use pacts to wetlands, chemical transport, verification in assessing water quality problems, allocating of water quality and wasteload allocation models, source loads, and evaluating alternative manage- flood plain delineation, streamflow forecasting, and ment strategies; and expand modeling capability hydrological/meteorological forecasting. No attempt to include toxics, especially with regard to sediment is made, however, to relate general goals to specific processes. 12 agency activities, or to recommend divisions of responsibility and funding allocation levels among

8’ ‘Water Research Priorities for the 1980’ s,” Department of the agencies. The report provides broad guidelines to Intcrlor, Office of Water Research and Technology, April 1979. agencies conducting research and analytical activ-

9 “ Interim Report-priorities in Federal Water Resources Re- search, Department of the Interior and the Oflice of SC icncc and ities, but addresses none of the management con- Technology Policy, August 1979. cerns outlined in the 1978 act. ‘0’ ‘Proposed U.S. N’ational Water Resources Research, Develop- ment, Demonstrate ion and Tmhnolo,gy Transfer Program, 1982-1987, The differences between the two agency compila- Draft, Department of the Interior, December 1980. tions and the ‘ ‘Interim Report’ suggest one of the ~ ~ Ftdma[ Walu ResOurce3 Re~earch A Review of the Proposed Flue- Year Program Plan, Water Resources Research Review Committee of the major difficulties in creating an overall Federal ,National Research Council (Washington, 1). C. : National A( acfemy Prrss, 1981), ‘ ‘Ibid, p. 9. 1“ ‘Water Rescm-ch Priorities f’or the 1980’ s,” p.67, 141hid, p. 63. Ch. 4—Federal Use and Support of Water Resource Models ● 79 strategy for water resources R&D. From the per- OTA’S survey of Federal water resource model- spective of each Federal agency or program, models ers and of related studies suggests that directives and research are valuable primarily for their con- for formulating an overall Federal plan for water tribution to specific program objectives. Alter- research and technology should specifically address natively, an overview of national water resource the relationship between research and developing problems can show areas in which lack of computer- usable analytic tools. Priorities and allocation of based information prevents important advances in funding and manpower need to be set for both kinds identifying needs, creating cost-efficient control of activities, as well as for mechanisms to transfer strategies, and developing better administrative and modeling expertise and increase model availabil- legislative tools, Making agencies more responsive ity to Federal, State, local, and private sector users. to such national-level concerns requires concerted, ongoing efforts at highest management levels to in- Role of the State Water Resources Research tegrate overall objectives into routine agency deci- Institutes in Coordinating Federal sions and funding allocation procedures. Water R&D Policy The NAS evaluation of the proposed 5-year pro- The Water Resources Research Act of 1964, and gram plan also sets out to define broad problem its successor, the Water Research and Development areas in which further water resources research is Act of 1978, provided for the establishment of a needed. It focuses, however, on analyzing inade- network of State water resources research institutes quacies in the December 1980 draft, and identify- at a designated land-grant college or university in ing institutional constraints to the development and each State. Under the auspices of the Office of implementation of a coordinated long-range Federal Water Research and Technology (OWRT) in DOI, plan. The NAS study points out the inadequacies the institutes have funded a wide variety of research of a focus on research per se—rather than on a programs in water resources. Since its inception, broader range of analytical and support needs— the State Institute Program has involved over as a major defect in the DOI/OSTP coordinating 35,000 professionals and students in water-related effort. research and problem-solving studies. Funding has been provided by OWRT on a matching basis with The report by its title purports to cover more than ‘ ‘water research’ ‘—namely, ‘‘development, State governments under two separate programs: demonstration, and technology transfer, ’ although 1) a basic allocation of $110,000 per State (as of these terms are not defined. Rigorous attention is fiscal year 1980), and 2) a competitive grants pro- not given to distinguishing those separate activities gram allotting a total of over $5 million (as of fiscal in the program statements of the individual agen- year 1980). However, for fiscal year 1982, the com- cies, and no overall assessment of these activities petitive grants program has been eliminated, while is included in the program. The instructions to the the basic allocation to individual States has been agencies mentioned only research. 15 reduced to the $110,000 1980 figure. In addition, The NAS study further concludes that the direc- OWRT has been scheduled for elimination, and tives of the 1978 act are insufficient in themselves its duties and responsibilities transferred to other to provide a basis for coordinated Federal ap- offices and programs, before the end of the current proaches to water resource R&D. fiscal year. The deficiencies noted in the draft of the five- The State Institute Program has proved to be an year program report are convincing evidence that efficient, effective means of encouraging a wide the ad hoc approach to management of the Federal variet y of water research efforts. In fiscal year 1979, water research program will not yield the results the latest year for which detailed cost statistics are

expected by Congress when it enacted the Water available, total Federal support of slightly over $21 16 Research and Development Act of 1978. million elicited a nearly equal commitment of State

—.— ‘I ~“l’herC arc ‘ urrf.nt]~, 51 lnst itutcs-onc pcr state, and add itlt}na! ]nst ltut ions in }$’ashlnqon, D.C , Puerto Rico, Guam, and [hc \’lrgtn Islands. 80 Use of Models for Water Resources Management, Planning, and Policy and private funds. During that year, the program planned simultaneously with model development, supported the work of about 1,200 principal investi- modeling activities must be adjusted to the available gators and about 1,750 student research assistants. data resources. This makes coordination of water Modeling activities constitute an important com- data collection extremely important to successful ponent of institute efforts, and increased training use of water resource models. opportunities in model-related skills for water Hydrologic data are collected by a large number resource professionals have been one of the pro- of governmental and private entities, normally in gram’s major byproducts. order to serve some specific informational purpose The 1978 act also designates the institutes as the or in support of established program activities. His- principal source of information regarding State torically, such data were collected under methods water research needs for use in creating the Federal and standards devised to suit an organization’s or 5-year program plan. Each institute is required to agency’s individual purposes, and were stored away submit to the Secretary of the Interior for approval once the organization’s needs for it were met. While an annual program “developed in close consulta- some general-purpose data on the quality and quan- tion and collaboration with leading water resources tity of the Nation’s available water resources were officials within the State’ and ‘‘to cooperate with routinely collected and disseminated by the Water the Secretary in the development of five-year water Resources Division of the U.S. Geological Survey resource research and development goals and objec- (USGS), potential users of water data frequently tives. encountered difficulty in identifying and locating existing data bases. Afterwards, even when such The scope of institute activities varies greatly data were located, they were often found unusable, from State to State. Some institutes focus on ana- due to collection methods and/or standards of accu- lytical work in cooperation with State water agen- racy that failed to meet user requirements. cies; others concentrate on more traditional research functions. The diversity of the activities and con- In 1964, to aid in coordinating water resource cerns of the 54 State institutes is highly appropriate data, the Office of Management and Budget (then to their research missions, but has mixed implica- the Bureau of the Budget) issued Circular A-67, tions for relaying State agency needs in water re- assigning the role of lead agency for such activities source R&D to Federal policymakers. The institutes to DOI, which assigned specific responsibility for are closely connected to the academic institutions this function to USGS. To carry out this responsi- at which they are housed, and are not alined with bility, USGS created OWDC, and gave it the fol- any one State agency. Their freedom from mission- lowing principal responsibilities: oriented concerns and priorities gives them the po- exercising leadership in achieving effective co- tential to represent the needs of all the State-level ordination of water data acquisition activities; water resource agencies. However, since the insti- undertaking continuing and systematic review tutes are staffed primarily by research scientists with of water data requirements and activities; professional ties to universities, they are not in- preparing and keeping current a Federal Plan volved with day-to-day State agency problems. to aid in coordinating agency water-data acquisition efforts; Existing Governmentwide maintaining a central Catalog of Information Mechanisms for Coordinating on Water Data and on Federal activities being Modeling and Model-Related planned and conducted to acquire water data; Information and designing and operating a national network Office of Water Data Coordination (OWDC) for acquiring data on the quality and quanti- Since water resource modeling tends to be highly ty of ground and surface waters, including the data-intensive, model developers and users are par- sediment loads of streams. ticularly vulnerable to problems of data availabil- Major programs of OWDC most relevant to ity. Unless the collection of required data can be modeling needs include: Ch. 4—Federal Use and Support of Water Resource Models ● 81

Photo credit: @ Ted Spiege/, 7982

Banks of disk-drive units retrieve and store information at USGS headquarters in Reston, Va.

Federal Plan. —A key coordination document, investigations and miscellaneous activities. Special summarizes the plans and needs of agencies acquir- indexes such as the four-volume ‘‘Index to Stations ing or using water data. It brings these plans in Coastal Areas’ have also been published. An- together at the level of each of the 21 national other special index currently being prepared covers regions of the Water Resources Council—the re- water data acquisition activities in the major coal gional plans are then assembled as the basis for the provinces of the United States. unified Federal Plan. Ongoing field-level review and Interagency Advisory Committee oversight are National Water Data Exchange (NAWDEX). employed to achieve coordination at local and na- —A national confederation of water-oriented tional levels. organizations working together to improve access to water data. Developed by a working group of Catalog of Information on Water Data.—A the Interagency Advisory Committee on Water computerized file of information about water data Data, it has a function which the Catalog of Infor- activities. Currently, the catalog is divided into four mation on Water Data only partially fulfills-that sections: 1) streamflow and stage; 2) quality of sur- of assisting users of water data in identifying, locat- face water; 3) quality of ground water; and 4) aerial ing, and acquiring needed data. NAWDEX members are linked so that their several water data ‘8’ ‘Plan for Water Data Acquisition by Federal Agencies Through fiscal year 1982, Office of Water Data Coordination, USGS, Depart- holdings may be readily exchanged for maximum ment of the Interior, August 1980. use. Coordination and overall management for the 82 . Use of Models for Water Resources Management, planning, and policy program is provided by a central program office descriptions of new or substantially revised research within the Water Resources Division of USGS. projects in water resources. Until October 1981, the file was compiled by the Smithsonian Scientific Water Resources Scientific Information Center Information Exchange (SSIE) from material volun- (WRSIC) tarily registered there by Federal and other research organizations. NTIS has recently been given re- An early priority of COWRR was the establish- sponsibility for compiling the Research in Progress ment of a central facility to collect and disseminate File, and is developing procedures to streamline the information relating to water resource analysis. In compilation process. Since file entries refer to ongo- response to its recommendations, under the author- ing work, the file reports projects substantially in ity of the Water Research and Development Act advance of SWRA, which can reflect only published of 1964, DOI created WRSIC within OWRT (then findings. File information is accessible through the Office of Water Resources Research) in 1966. computer retrieval systems at NTIS and through WRSIC is primarily a management and support the private sector. unit that funds the compilation of information by Both the Research in Progress File and SWRA other organizations. It does not collect and store contain information about models and modeling published material, nor does it have a staff of ab- activities. However, since they are designed for stracters, indexers, and support technicians. It con- much broader purposes, abstracts and research tracts with a variety of governmental and private projects are referenced originally by subject areas organizations to collect information under service —and are cross-referenced only under the general and funding agreements, and produces publications category, ‘‘model studies. It would be extremely and computerized records by arrangement with ad- difficult for these general bibliographic reference ditional government organizations. Its two major services to adequately address the specialized nature information systems have been the Selected Water Re- of modeling needs without making substantial sources Abstracts (SWRA) and the Water Resources changes in their capabilities—such as the ability to Research in Progress File. Recent budget reduc- store and distribute computer programs. tion initiatives have cut WRSIC appropriations from over $900,000 for fiscal year 1981 to under $600,000 in fiscal year 1982, and have eliminated National Technical Information Service WRSIC support for the Research in Progress File. NTIS of the Department of Commerce serves Material for SWRA is collected primarily by pri- as the primary source for the public sale of Govern- vate centers of competence in particular water re- ment-sponsored research, development, engineer- source fields, supplemented by additional informa- ing reports, machine-processable data and related tion from Federal agencies, State water resources software. It adds approximately 70,000 new reports research institutes, and a commercial abstracting annually to an information collection of over 1 mil- service. The material is processed at the National lion titles, of which over two-thirds are computer Technical Information Service (NTIS), and made retrievable. NTIS publishes a number of user-infor- available in two forms: a journal, SWRA, pub- mation reports to keep users informed of available lished semimonthly, and computerized biblio- material, including a comprehensive biweekly jour- graphic retrieval services available through DOI nal summarizing new publications, 26 weekly ab- and private sources. Approximately 15,000 new stract newsletters, with annual indices, and over bibliographic entries are published and added to 2,000 bibliographies. NTIS analysts are also avail- the system each year. The abstracts system current- able to match user requests to available material, ly holds over 150,000 full bibliographic references. using online computerized master files. WRSIC also uses the system to produce and publish In addition, the statutory mission of NTIS in- an extensive topical bibliography series, and the cludes the collection and sale of data files and com- OWRT research reports. puter programs from Federal sources. These are The Water Resources Research in Progress File Catalog made available to users on magnetic tape, while is an annual compilation of about 2,500 summary documentation in the form of user and program- Ch. 4—Federal Use and Support of Water Resource Models ● 83 ing manuals is available in printed copy or on FSEC at NTIS. The regulations specify that these microfiche. Models must already be documented computer programs must have been operational for in order to be listed in NTIS files. Computer-based at least 90 days, and require agencies to provide material is primarily indexed under the subject particular forms of documentation with the ab- area(s) to which it refers—a retrieval system was stracts. FSEC currently compiles the submitted ab- developed specifically for locating computer tapes stracts into the GSA Software Exchange Catalog, and of models, but was poorly suited to this purpose. sets prices for Federal, State, and local government More recently, NTIS files of computer models have agencies wishing to use the listed computer pro- been combined with those of the General Services grams. Subscriptions to the catalog are provided Administration (GSA) Federal Software Exchange for a $75 annual fee. Center (FSEC), as described below. No mechanisms exist, however, for enforcing Following the elimination of SSIE, NTIS has re- participation in the software exchange program. cently been designated to compile the Research in The determination of which programs are suitable Progress File, the water research portion of which for interagency use rests with each agency, and was previously funded by WRSIC. As no funding GSA has authority to do little more than persuade was allocated to NTIS for compiling the file, the agencies to submit abstracts. Consequently, re- agency can only accept Notifications of Research sponses to the program have not met expectations in Progress for which submitting agencies have pro- —while GSA and NTIS officials planned for the vided indexing and other preparatory work for com- receipt of up to 7,000 abstracts in fiscal year 1977, puter retrieval. the first year of the center’s operation, the inven- Because water resource models constitute only tory currently contains only about 1,300 abstracts, a small percentage of the software suitable for a minute fraction of the entries in the NTIS system, exchange. proposals for increasing general NTIS capabilities to locate them and advise potential users about their For a program to be included in the Software Ex- functions are difficult to justify. As a general-pur- change Catalog, agencies must submit a tape of the pose information center that is obligated by law to actual program, documentation, and an informa- recover its costs from sales and distribution of prod- tion sheet specifying basic program characteristics. uct and services, NTIS cannot affort to serve as All software packages are routinely reviewed for a modeling resource center. With regard to com- completeness, but FSEC staffing levels do not gen- puter programs, it can be an effective mechanism erally permit the evaluation of submitted programs. for the distribution of an already-known model, but Consequently, the FSEC inventory consists primar- its functions are too broad to permit its effective ily of general submissions of unknown quality. Only use as a focus of modeling expertise and informa- a very small percentage of inventoried programs tion. have been tested and enhanced by GSA, or are considered to be of special significance and known reli- GSA Federal Software Exchange Center ability. Moreover, to satisfy agency fears about re- The Brooks Act of 1965 (Public Law 89-306) ceiving large numbers of direct inquiries regarding gives GSA authority to develop governmentwide computer programs, software exchange program guidance for automatic data-processing activities. regulations further specify that the developer of sub- Under this authority, GSA amended the Federal mitted computer programs will not be identified to Property Regulations to create a Federal Software purchasers without the developer’s prior consent. Exchange Program in February 1976. To imple- Providing technical assistance to users has not ment the program, GSA created FSEC by inter- been included as a major part of the FSEC mis- agency agreement with NTIS, using funding from sion—less than one staff-year of time was budgeted the GSA automatic data-processing revolving fund. for this purpose for the first year of the center’s The Federal Property Management Regulations operation. GSA’s policy of recovering the costs of require agencies to submit abstracts of computer the program through sales of computer software ap- programs considered usable by other agencies to pears to preclude higher levels of assistance. How- 84 . Use of Models for Water Resources Management, planning, and policy

ever, since potential users frequently have no ac- Resources Division of USGS. A problem-solving cess to developers under the program, many avail- focus is provided by the USGS Federal-State Co- able models will remain unused for lack of the tech- operative Program, which assists State and local nical guidance required to adjust them to particular agencies in acquiring needed water resource infor- user needs. An early GAO report on FSEC activi- mation on a case-by-case basis, using analytical ties (1978) summarizes: resources throughout the division to develop site- specific models that deal with the particular prob- The GSA Software Exchange Program, as presently operated, is primarily a catalogue sales opera- lem at hand. These two approaches are described tion. In our opinion, many agencies will not buy in greater detail below to illustrate the major op- software from this source because adequate techn i- tions available for agencywide coordination of mod- cal assistance is not being provided. eling activities. In addition, a third organization— the Instream Flow Group of the U.S. Fish and To enhance intra-agency software use, and ex- Wildlife Service—is presented to illustrate the pand the base for submissions to the FSEC inven- potential for advancing model use and modeling tory, FSEC has recently begun to offer technical capabilities through innovative interdisciplinary, in- assistance to Federal agencies on a reimbursable teragency analytical work. basis for establishing internal software inventories, and setting up coordination mechanisms for soft- Army Corps of Engineers’ HEC ware development and use. FSEC is also negotiating with various specialized groups to catalog Established in 1964, HEC provides assistance in software in topical categories, geared to specific applying state-of-the-art technology (primarily classes of users. mathematical models) to current hydrological planning, design, and operation problems. While Existing Support Structures for HEC’S initial purpose was to provide hydrological Agency-Level Modeling Activities engineering services to the Corps of Engineers 52 offices, it currently supports the development and The majority of Federal agencies that currently implementation of a broad range of water resource use water resource models lack comprehensive strat- analysis and planning techniques. Services are pro- egies for developing, using, and disseminating these vided extensively to non-Corps of Engineers users tools. Modeling activities and expertise are dis- —private firms; other Federal, State, and local gov- persed throughout most of the agencies surveyed ernment organizations; universities; and foreign by OTA, with little apparent coordination, commu- organizations—which currently account for over 80 nication, or sharing of resources among individual percent of HEC model use. modeling projects. However, two of the major users HEC professionals locate, evaluate, and/or devel- of water resource models—the Corps of Engineers op new procedures and techniques for analyzing and USGS—have developed programs that inte- water resources; develop and maintain 12 major grate all major phases of modeling activity, and computer models; teach currently available tech- function as a focal point for serving the modeling niques and model use in formal training courses; needs of nonagency users. and assist Corps of Engineers offices and others in The two organizations employ widely divergent applying models and techniques to current studies. approaches for supporting model-related activities. To provide readily accessible user assistance, HEC The Hydrologic Engineering Center (HEC) of the assigns each of its major models to one or more Corps of Engineers is a discrete organizational unit engineers, who answer user questions over the tele- that develops and supports a limited number 01 care- phone and handle unforeseen difficulties that may fully selected models for use in a wide variety of ap- arise. plications, By contrast, model development if dispersed HEC has evolved a number of basic guidelines throughout the research activities of the Water to ensure the widest possible use for the models it —-— develops and/or maintains. Models are designed ‘<’ ~fit }kfera[ .$~J~tLL’aTt’ btxchun,qe /%gram-A .hnu[[ .\’tip In lmproutn,q L’om - for general use, so that most problems in a field puta /’ro~ram .\’harlnq, (;tncral At { (junting (J1’fi( c, January 1978, p. 13. of interest can be solved with the same model, and Ch. 4—Federal Use and Support of Water Resource Models ● 85

into the computer are designed for simplicity, and are thoroughly described in the user’s manual. HEC distributes copies of its models and documentation without charge to a variety of users; private firms are charged a nominal fee for repro- duction and handling costs. A November 1976 sur-

vey showed an annual distribution of approximately 700 model copies, and found that over 2,700 copies of HEC models were still in use by the offices that received them. HEC also publishes newsletters, professional papers, computer program abstracts, and training course notebooks to promote the use of its models. Training courses are an integral part of the HEC user assistance program. The center provides 24 weeks of training courses annually for Corps of Engineers staff, reserving approximately 10 percent of the space in these courses for non-corps of Engineers personnel. A number of the HEC-developed courses have also been adopted for use by U.S. and Canadian universities. Fifteen of the HEC courses have been videotaped; tapes and in-

structional material are available for loan, and may be used by visitors to HEC in conjunction with individualized instruction from center staff. Despite these efforts, however, HEC staff acknowledge that insufficient training is currently available to the Photo credit: @ Ted Spiegel, 1982 non-Corps of Engineers user. Extensive field investigations, analyses, and public participation are part of the planning process for the Army Corps of Engineers’ study of the Passaic River USGS Water Resources Division Basin. HEC provides analytical support for Corps studies, using a wide variety of modeling and USGS is a service-providing organization other planning techniques charged with collecting data on and analyzing the Nation’s physical resources. Its Water Resources require little or no program modifications. Com- Division collects long-term multipurpose data on monly accepted techniques are used where possi- surface water, ground water, water quality, and ble, and a variety of approaches is provided within water use; performs special interpretive studies of an overall modeling package to suit individual needs the physical, chemical, and biological characteristics and preferences. All programs are written in a com- of water; and conducts appraisals for environmental monly accepted computer language (FORTRAN impact evaluation, energy development, coastal IV), and are also designed to be easily transport- zone management, subsurface waste storage, waste able to a wide variety of computer types. utilization, land-use planning, flood plain management, and flood warning systems. Water resource The ease with which the model can be used is models are used in all phases of the divisions activ- also an important design criterion. To document ities, and are an integral part of its analytical capa- models, HEC develops both user’s and programer’s bilities. manuals. The user’s manual is written both to allow the beginner to use the model easily and to permit The division undertakes a substantial amount of experienced users to employ the model for com- data gathering, resource investigation, and research plex problems. The procedures for entering data for general use throughout the Federal Govern- 86 Use of Mode/s for Water Resources Management, Planning, and Policy

ment. It also carries out work to meet the analytical needs of other Federal agencies on a cost-reimbursable basis, involving funding tranfers of nearly $30 million in fiscal year 1978. Nearly half the division’s budget, however— $70 million for fiscal year 1978 —was involved in activities carried out for the Fed- eral-State Cooperative Program. The program, funded on a 50-50 basis by the division and State and local governments, provides data, information, and analyses to over 600 non-Federal agencies, concentrating on problems whose solutions are of mutual benefit to Federal, State, and local water resource professionals and decisionmakers. More requests for studies and offers of matching funds are received by the division each year than can be undertaken under current funding levels; decisions and negotiations regarding projects are made on a decentralized basis through 47 district offices. Most arrangements for undertaking studies are for- malized with a simple one-page standard cooperative agreement. Research and analytical work for the cooperative program is implemented under USGS direction, principally by Water Resources Division staff. These activities take place primarily at the division’s regional centers in Reston, Va., Lakewood, Colo., and Menlo Park, Calif.; at the Gulf Coast Hydro- Photo credit: @ Ted Spiegel, 19S2 science Center at Bay St. Louis, Miss.; and occa- USGS investigations of water problems are often coupled sionally in other sections of the country as needed. with laboratory resaarch and modeling activities to The combination of decentralized planning and provide the information necessary for a thorough coordinated interdisciplinary analysis at central analysis. Here, a USGS research scientist demonstrates computer-controlled lab equipment used to make locations allows the program both to be responsive calculations for the study shown in foreground to real-world problems and indications of emerging priorities, and to pool manpower and expertise in the relatively small field of hydrology. One of the keys to the strength of the USGS effort is the reputation for impartiality enjoyed by When a model is needed to perform a particular the division’s studies. Many of the projects it un- analysis, USGS professionals develop one to suit dertakes are associated with controversies among the specific site characteristics under study. Thus, conflicting interests. Because the division’s analyses each model developed by the division is an in- are perceived to be relatively free from mission-ori- dividually tailored, single-use model, though it may ented biases, its results tend to be accepted by all often be based in part on a previously developed parties to interstate, intrastate, State-local, and in- research prototype or an earlier modeling effort. ternational disputes. Models and model-related activity account for between 10 and 12 percent of the Water Resources USGS also provides extensive hydrological and Division operating budget—from $12 million to $15 water resource-related training. Courses are con- million was spent on applying models to specific ducted primarily at the USGS National Training problems, and from $3 million to $4 million on re- Center at Lakewood, Colo., and include a large search, in fiscal year 1979. number of sessions on modeling surface water, Ch. 4—Federal Use and Support of Water Resource Models 87 ground water, and water quality. Open to person- Potential users of Instream Flow Group (IFG) nel throughout the Federal Government and from services identified two major needs: 1) information State agencies and international organizations, on biological and hydrological aspects of instream courses are geared toward various levels of profes- uses; and 2) information on institutional means cur- sional expertise, some of them designed for admin- rently (or potentially) available for ensuring ade- istrators, others for technicians and resource special- quate stream flows. Satisfying these needs required ists. Nationally and often internationally recognized the creation of a team of personnel encompassing scientists and engineers from the Water Resources the biological, physical, and social sciences to Division serve as the main instructional staff for gather, collate, and disseminate information on in- training sessions. Experts from other divisions of stream uses. Model developers and users were also USGS, other Government agencies, universities, considered a necessary part of the team effort, in and private industry also serve as lecturers and order to create usable mathematical tools for in- special consultants. stream analysis. Staffing for IFG was accomplished through the Fish and Wildlife Service, State agen- Cooperative Instream Flow Service Group cy personnel recruited under the Intergovernmental Personnel Act, and detailees from other Federal The extensive development of water resources agencies. in the Western United States over the past 15 years has had major effects on the availability of water Since its inception, the group has concentrated for instream uses such as recreation, and fish and on transferring information on instream uses via wildlife needs. During this period, concern over computerized data retrieval systems, library func- rapid decreases in instream water availability cre- tions, preparing information papers, training, and ated broad-based expressions of need for a compre- providing technical assistance on various aspects hensive source of information and expertise on of stream flow protection. Two of its major analyti- standard tools for analyzing instream water needs. cal efforts have been in developing methods to: Such concern reached major proportions by the 1) analyze the effects of incremental changes in flow mid- 1970’s— particularly in the Pacific Northwest, on instream uses such as fish and wildlife habitat; where protection of the anadromous fish resource and 2) analyze tradeoffs between instream and off- has been an acute problem for many years. stream uses as part of regional water assessments. During the early 1970’s, a number of entities en- In the first area, IFG has developed the instream gaged in analyzing instream flow problems both flow incremental methodology, an analytic ap- from a technical and legal/institutional perspective. proach to evaluating changes in the fish-carrying The general response of natural resource manage- capacity of stream reaches. This methodology has ment agencies, and the U.S. Fish and Wildlife Serv- been widely adopted for use in Western and Mid- ice in particular, was to organize groups of fisheries western States. For the second area, work is in prog- or wildlife biologists to make suggestions to the ress for a regional reconnaissance method to evalu- water management community. This approach ate general stream characteristics within a water proved relatively unsuccessful, as resource manag- basin. Using the Upper Colorado River Basin as ers were not inclined to give strong credence to a a case example, the group is attempting to develop solely ‘ ‘biological’ perspective. As an alternative, a unified basin modeling approach as a decision- the Office of Biological Services within the Fish and making tool to determine the cumulative effects of Wildlife Service proposed to develop an inter- various water management schemes. disciplinary, service-oriented center for instream flow analysis, drawing personnel from numerous The group provides two types of assistance to im- Federal and State Government agencies. Funding prove the level of competency among users of its

to create this center— the Cooperative Instream computer-based models. First, it offers an array of Flow Service Group—was eventually provided training opportunities designed to inform participants through EPA for fiscal years 1976 through 1979. about the basic issues, develop an overview under- Funding is currently provided directly by DOI. standing of solutions to the problem, and finally, 88 . Use of Models for Water Resources Management, Planning, and Policy provide instruction in using computer-based ing System (LAWREMS). Each represents a submodels. The group maintains an extensive train- stantially different approach to managing modeling program throughout the Western United States related information and improving user access to on such subjects as western water law, strategies existing modeling systems, and addresses different for protecting instream flows, and negotiating in- kinds of user needs. stream flows. In addition, the group offers training in the use of modeling technologies. For exam- International Clearinghouse ple, its instream flow field techniques short course for Groundwater Models and its computer analysis short course are designed Studies begun in 1975 at the Holcomb Research to give the user the technical competence required to conduct analyses of instream flow requirements. Institute indicated that, while significant progress had been made in developing and using numerical Second, IFG provides technical assistance. This en- models for ground water-related resource manage- tails helping users who are engaged in instream flow ment, major gaps existed between the need for and analysis to develop study plans, make measure- the existence and actual application of ground water ments, analyze data, develop and present recom- models. Access to existing models, and identifying mendations, and implement them. Technical as- models designed for specific applications, were sistance also involves assisting State and Federal observed to be serious problems. The gulf between water administrators in determining areas and op- model developers and model users needed to be portunities for factoring instream uses into State closed by developing mechanisms for transferring water plans or land management plans. modeling technology from experienced modelers to others needing these important analytical tools. IFG officials attribute the group’s success to its strong interdisciplinary focus, the quality of its per- Further research work, funded by EPA and the sonnel, clear identification of the problems to be Scientific Committee on Problems of the Environ- addressed, and frequent interaction among staff ment, developed guidelines for establishing a clear- members and group leaders. The communication inghouse to assist users of ground water models, engendered among professionals in a number of and an outline of the primary objectives and serv- disciplines is considered a vital prerequisite to devis- ices of such a center. ICGWM became operational ing methodologies, solutions, and recommendations when EPA funded a 3-year project to staff and fulfill credible to the wide range of interests that are party the clearinghouse objectives at the Holcomb Re- to water resource management decisions. search Institute. The project is intended to test the utility of the clearinghouse approach to technology Agency-Level Mechanisms for transfer using ground water models as an example. Providing Information on and The clearinghouse concept is based on the idea Access to Existing Models that a central information source can greatly reduce the effort normall required to acquire model in- A number of mechanisms are currently used in y formation. Through the clearinghouse, the poten- various Federal agencies for making model-related tial user can be exposed to all levels of available information available to users. Such services may technologies and can expeditiously determine which range from simple directories of available models; is most appropriate for his purposes. Further, a to user support groups for transferring modeling clearinghouse provides a natural setting for testing to clearinghouses that match user technologies; and evaluating models, and for education in model needs to available models, test and evaluate model- applications, operations, and theory for nontech- ing systems, and provide user training. Four major nical and technically trained personnel alike. agency efforts are described below: 1 ) the Interna- tional Clearinghouse for Groundwater Models The first major activity of ICGWM was to devel- (ICGWM); 2) the EPA Stormwater Management op a ground water model information search and Model (SWMM) User’s Group; 3) the EPA Cen- retrieval system. A model annotation form—a deter for Water Quality Modeling; and 4) the USDA tailed checklist containing both general and specific Land and Water Resources and Economic Model- model characteristics—was circulated international- Ch. 4—Federal Use and Support of Water Resource Models . 89 ly to known model developers, with a request to sessions are ‘‘hands-on’ experiences where the at- complete the form by checking off those characteris- tendees vigorously work with computer models and tics that apply to their models. These forms were developers. The first series of workshops was con- used to develop a computer-assisted Model Annota- ducted with an enrollment of 140; indications are tion Retrieval System (MARS). As of February that the workshops have been highly successful in 1982, MARS had over 400 unique model annota- educating water resources professionals about the tions— and their number is constantly growing. potential of models. Future plans call for presenting the general session at regular time intervals at To access information, the same model annota- regional centers throughout the United States, and tion form is distributed to interested model users. the entire workshop series at various international The user checks off the desired model characteristics locations. and returns the form to the clearinghouse, where MARS compares it to the stored models and iden- The third phase of development calls for estab- tifies those that meet all or most of the desired lishing formal international linkages to the center, characteristics. This retrieval system is designed to and developing financial support to continue the avoid the complexities that plague traditional expansion of the clearinghouse. To the latter end, systems controlled by key words. Its success can ICGWM plans to undertake technology transfer be gaged by the fact that user requests for model activities to assist users, operating under an estab- information grew from an average of 6 per week lished fee structure for technical consulting work. during the first 6 months of operation to 85 per However, charges for these services, the workshops, week as of April 1980. and the use of MARS are unlikely to cover the cost of daily operations—outside sources of funding will Moreover, developers have begun to recognize need to be secured to support clearinghouse ac- the commercial value of having their models in- tivities. ICGWM officials suggest that an appraisal cluded in MARS. Evidence of competition has of the cost effectiveness of the center will only be recently been observed among developers to ensure possible once all of its major activities are fully that their works are available to potential users operational. Over time, however, as demands for through the clearinghouse. services grow, the clearinghouse is likely to require The second phase of development at the clearing- less financial assistance from outside sources. house involves the acquisition, evaluation, and rec- ICGWM officials consider that the clearinghouse ommendation of available models. ICGWM is cur- has been successful thus far in making ground water rently assembling a selection of functional models modeling information accessible, in reducing the that: 1) are available; 2) have been tailored to cur- time and effort required for model users to acquire rent key ground water problems; and 3) have been appropriate modeling tools, and in educating inter- tested for accuracy, usability, and transferability. ested professionals about the benefits and limita- A screening process is being developed to examine tions of models. The clearinghouse approach also models for validation and performance, and to cre- appears to hold major potential as an effective mediate documentation guidelines for model software. um through which new technologies can be trans- In the process, close attention will be given to the ferred. model user’s manual compiled by the model developer. SWMM User’s Group The other major activity started during the second phase of development is a series of workshops EPA’s SWMM is one of the largest and most on ground water modeling. The workshops, held comprehensive mathematical models for simulating annually at the Holcomb Research Institute, are storm and combined sewer systems, their associated structured in a stepwise fashion, beginning with a storage and treatment facilities, and their impacts general introduction to the applications and limita- on receiving waters. Its reliability and widespread tions of models for policy makers and decision- availability have made SWMM the most widely makers, and progressing toward advanced mathe- used model of its type in the United States and matical theory in later workshops. The last three Canada, and have been important in increasing the 90 ● Use of Models for water Resources Management, Planning, and Policy use of models by engineers and planners. The When the model first became operational, EPA’s SWMM User’s Group has been instrumental in Office of Research and Development (ORD), achieving the widespread dissemination and accept- which sponsored the development of SWMM, de- ance enjoyed by this important modeling tool. cided to organize an informal user’s group as its principal means of technology transfer. ORD rec- Initially developed in the early 1970’s, SWMM ognized that the model’s principal users would not is a complex, computer-based model that simulates be EPA staff, but rather the members of the consult- the movement of stormwater through a watershed, ing engineering profession, acting on behalf of determines quantity and quality of runoff, routes EPA, or of State, regional, or local governments, this runoff through a combined (or separate) sewer or industrial and commercial clients. These model system with specified storage and treatment facilities ‘‘clients, who are normally free to select the mod- and operating policies, and thence into receiving els to be used, generally base their decision on a waters, where resulting water quality is quantified. model’s ease of use, cost effectiveness, and reliabil- SWMM is modular, having five computational ity. blocks—each of which can be used alone or with To assure that SWMM would be readily usable, other blocks. ORD devoted substantial attention and resources

Photo credit: @ Ted Spiegel, 19s2 Modern urban development has substantially increased both the complexity of urban runoff management and the need for adequate sewer transport, storage, and treatment of runoff. The Albany, N. Y., skyline provides a dramatic demonstration of the interactions between built-up urban areas and natural water bodies. Models such as EPA’s SWMM can be used to assess the impact of Albany’s runoff on flows and water quality levels in the Hudson River Ch. 4—Federal Use and Support of Water Resource Models 91 to documenting and testing the model before at- efforts tend to become self-perpetuating and to stifle tempting to disseminate it. All or parts of SWMM creative change. In addition, the group that main- were tested in five different locations, and the results tains the model is available to users for over-the- of the tests included in the original documentation. telephone questioning or detailed consulting on a This, in the judgment of the SWMM developers, normal fee basis. This supplements the informal was the single most important factor in gaining ac- free advising network among users, and the avail- ceptance for the model. ability of User’s Group members to consult on a fee basis when needed. EPA has resisted requests The first step in creating a technology transfer to make minor changes in the program. Three up- program for SWMM was to set up a mechanism dated versions of the model have appeared since for distributing the model and its documentation. the original; users are encouraged to make other Working from a small list of interested people, local changes that they desire. ORD offered to duplicate the model and documentation for anyone who sent in a blank tape. Since Initially, training in the use of the model was

1972, over 300 users have received copies of the sponsored by EPA; since 1976, however, the only program, and perhaps 1,000 copies of the documen- available formal training has been offered private- tation have been sent out. Test data are furnished ly by various universities. The agency’s experience with the program to allow each recipient to check has been that, given the support of the User’s that the model is operating correctly. Group, model users are generally willing to train themselves. In this sense, the User’s Group has User’s Group meetings were seen as the best evolved into an inexpensive alternative to agency- mechanism for transferring knowledge among expe- sponsored training programs. rienced model users and those who were new to SWMM. The meeting approach combines instan- Costs associated with the SWMM User’s Group taneous communication of current knowledge with have been relatively low. The group requires about close interpersonal association and support for 20 percent of the time of one professional, about model users. 10 percent of one secretary’s time, and about $5,000 per year to cover printing costs for meeting About 20 individuals attended the first SWMM proceedings. Other costs include mailing, newslet- User’s Group meeting in early 1973. Since that ter printing, maintaining the User’s Group list on time, meetings have been held on a semiannual a time-sharing computer, and duplicating the basis, and the group membership has grown to al- SWMM program —all of which consume perhaps most 500, including representatives from 19 foreign $2,000 to $3,000 per Meeting costs countries. An informal user’s bulletin, first pub- year at most. are minimal-since no travel expenses or honoraria lished in 1973, has been sent out periodically, to are paid to speakers— and are covered entirely by announce meetings or other items of interest. registration fees. User’s Group meetings are colloquial and informal in atmosphere, in order to allow a high degree EPA Center for Water Quality Modeling of interaction between individuals with common interests and problems. To encourage group mem- ORD established the Center for Water Quality bers to examine other models that may be made Modeling in 1980 to distribute, maintain, and pro- applicable to their problems, at least one presenta- vide technical assistance in the use of selected EPA- tion per meeting focuses on the use of a different developed water quality models. The center, located water quality model. Since 1977, formal User’s at the Environmental Research Laboratory in

Group proceedings have been published to record Athens, Ga., serves as a focal point for assisting meeting activities. users in locating and applying models developed by EPA operating and research programs. To maintain and update SWMM, ORD decided on the services of an outside contractor, rather than EPA’s use of water quality models increased rap- attempting to use in-house resources. The decision idly in the 1970’s. Separate model development ac- was based in part on the perception that in-house tivities within individual EPA offices resulted in a —

92 . Use of Mode/s for water Resources Management, P/arming, and policy — proliferation of seemingly different models, al- level of user interest dictates the number of work- though many models were actually modifications shops presented. For fiscal year 1980, several work- and/or extensions of earlier modeling attempts. The shops were held on the HSPF; two sessions were lack of a central reference point for model use within held on QUAL-11. A newsletter for informing users the agency impeded the correction of initial model- of training opportunities, advising them of modeling errors, so that errors tended to be propagated ing errors or updates, and quickly providing addi- in successive modeling activities. Additional impe- tional model-related information was introduced in tus for creating an office to support and maintain September 1980. Superseding and expanding on frequently used models came from the growing the SWMM User’s Group Newsletter, the new need to provide expert technical/analytical assist- publication has used the audience established by ance to States and EPA regional offices. The suc- its predecessor as a base for informing users of the cess of EPA’s own SWMM User’s Group and the center’s existence and activities. Current adminis- Corps of Engineers’ HEC in encouraging wide- tration policy, however, prohibits the center from spread model use and acceptance pointed to the publishing the newsletter. large potential benefits to be derived from such an office. At present, the center’s manpower resources are very limited; consequently, it does not offer routine The center’s initial support role has been limited ‘‘online’ technical assistance to all model users. to four widely used modeling packages: 1) QUAL- While limited technical assistance is available on 11 (a stream water quality model); 2) SWMM/ specific agency problems, and can be provided RECEIV (an urban runoff model); 3) ARM (an through procedures established prior to the center’s agricultural runoff management model) and NPS inception, even such requests are generally discour- (a general nonpoint source runoff model); and aged. To expand the availability of technical assist- 4) HSPF (a multipurpose hydrologic simulation ance in running models, the center concentrates on program). Center staff provide copies of model developing user interaction activities, based on the documentation and tapes of the models’ computer user group concept, in order to teach users to solve codes to interested users, and relay information their own problems. Such an approach has in the about errors or other problems back to the models’ past proved highly successful in encouraging the developers. Center personnel are currently use of standardized, widely applicable models. evaluating a number of models for possible addi- However, inclusion of additional, more specialized tion to the four packages presently being supported, models in the center’s support role would likely call and are developing a quantitative r-node] selection for the provision of greater levels of technical procedure to assist users. assistance by center staff. A number of older EPA models are also on file at the center; however, current manpower limita- USDA Land and Water Resources and tions do not permit them to be supported or main- Economic Modeling System (LAWREMS) tained. Computer programs, manuals, reports, A December 1976 request from the Senate Com- etc., for these models are distributed on request on mittee on Agriculture, Nutrition, and Forestry for a ‘ ‘use at your own risk’ basis. While the center USDA assistance in evaluating the department’s routinely receives requests for models in this cate- land and water conservation programs provided the gory, it has not checked, corrected or updated them, initial impetus for the creation of LAWREMS. As and functions primarily as an archive in this area. a followup to its report to the Senate, the USDA For its supported model packages, the center as- Land and Water Conservation Task Force created sists users by sponsoring intensive ‘ ‘hands-on’ a modeling team composed of representatives from workshops and technical seminars, taught by ex- major USDA agencies, giving it the responsibility perts from the Environmental Research Laboratory to develop an information system about current and representatives of the organizations that devel- data and analytical capabilities within the depart- oped the model under EPA grants or contracts, ment, and to outline future goals and directions for Workshops are open to all model users, and the integrated departmentwide modeling systems. Ch. 4—Federal Use and Support of Water Resource Models 93

The LAWREMS team developed a computer- improve communication among program analysts ized directory of data sets and models related to and researchers about existing data and models, water and land resource analysis, relying primar- their use, limitations, and linkages. The existence ily on those created by various USDA agencies. The of such a system is also intended to encourage the team also established a file of related documenta- upkeep, maintenance, and use of existing data files tion and reports, arranged for ongoing computer and models. Services are provided primarily to assistance to facilitate access to and transfer of data USDA analysts working in the area of resource con- and models, and created a small staff to maintain servation; however, expanding access to include the directory and provide limited technical assist- other USDA personnel, as well as interagency and ance to users. non-Federal use, has been envisioned as part of future LAWREMS activities. The initial LAWREMS directory contained approximately 300 descriptions of models and data LAWREMS support staff are responsible for sets, each of which included such information as maintaining and updating the directory, and pro- title, agency, an abstract, purpose, keywords, geo- vide some technical assistance to USDA land and graphic coverage, operational status, name and ad- water conservation program evaluators and ana- dress of technical contact, and basic technical in- lysts. Provision of “hands-on” training to a limited formation. The directory is currently housed within category of users on selected data and analytic Sys- the Resource Systems Program of the Economic tems is contemplated as part of ongoing staff activ- Research Service. ities. Staff would also provide assistance in coordinating agency efforts to design new models or mod- While LAWREMS support services include di- ify existing ones, along with identifying data re- rect access to a limited number of models and data quirements, when information is not available or sets within USDA, its primary function is to direct accessible from existing sources. users to the individuals or organizations that have developed these tools. The system is intended to Chapter 5 Use of Models by State Governments Contents

Page Summary of Survey Results ...... *. *. * * 0 . . * . * * * * * + . * * * * *.****.*. 97 Procedure Used in Conducting the OTA State Modeling Survey ...... 98 Trends in Current and Potential State Model Use ...... 98 Constraints to Model Use ...... 104 Developing Models To Meet State Needs ...... 104 Data Limitations ...... 105 Lack of Qualified Personnel ...... 105 Access to Federal Models ...... 106 Reliability and Credibility of Models ...... 106 Model Standardization ...... 107 Funding ...... 107 Model Maintenance ...... 107 Documentation...... 107 State Model Use in Individual Water Resource Issues ...... 108 Surface Water Flow and Supply Issues ...... 108 Surface Water Quality Issues ...... 110 Ground Water Issues ...... 113 Economic and Social Issues ...... 114

TABLES

Table No. Page 5. Number of States Indicating Existing or Potential Model Use ...... 99 6. Rankings of State Model Use for All Water Resource Issues ...... 101

FIGURES

Figure No. Page 7. Number of Water Resource Issues for Which States Indicated Current or Potential Model Use...... 100 8. Surface Water Flow and Supply Issues ...... 101 9. Surface Water Quality Issues ...... 102 10. Ground Water Issues ...... 103 11. Economic and Social Issues ...... 104 Chapter 5 Use of Models by State Governments

State governments have extensive water manage- understanding of models by State agencies is far ment responsibilities, ranging from flood control below the level it should be. To gain a better under- to prevention of ground water contamination to standing of factors affecting model use at the State comprehensive river basin management. These re- level, OTA surveyed professional-level personnel sponsibilities have increased in recent years, due at water resource agencies in all 50 States. This in part to Federal environmental legislation that chapter reports the results of that survey, including relies on Federal-State partnerships to address a the kinds of models used, the extent of their use, wide variety of national water resource problems. and the problems encountered by State water re- The Clean Water Act, the Resource Conservation source professionals. It contains: and Recovery Act, the Water Resources Planning summary of survey results; Act of 1965, and the Safe Drinking Water Act, in procedure used for conducting the OTA State particular, assign States numerous additional modeling survey; obligations requiring high levels of technical exper- trends in current and potential State model tise and highly sophisticated planning and manage- use; ment decisions. major constraints to model use identified by Computer models can significantly aid States in State personnel; and undertaking these added responsibilities. While sev- State model use in individual water resource eral States have sophisticated modeling capabilities, issue areas. many State officials acknowledge that the use and

SUMMARY OF SURVEY RESULTS

State water resource professionals generally use State officials indicated that increased Federal fund- computer models developed by others—particularly ing for data collection would improve State mociel- Federal agencies. The size, budget, and technical ing efforts, they also emphasized the importance capabilities of most State water resource agencies of improving access to Federal (and other State) do not permit them to develop models; consequent- data bases. ly, State model use depends on having access to federally developed models and on the availability Low salary levels and high turnover rates were of federally sponsored training and technical assist- also stressed as hindrances to States’ efforts to main- ance. tain staffs with expertise in modeling. After data needs, States placed highest priority on increased In many States, model use is primarily restricted federally sponsored training in model use and appli- to a few well-established, widely available models. cations for both technical and managerial person- State personnel are often poorly informed about the nel. other major State concerns included the need availability of models and data, and about technical for Federal sponsorship of simpler models for State- assistance available to facilitate model use. level use, and improving the reliability and credibil- Data inadequacy was the most frequently cited ity of models through Federal coordination, clear- constraint to effective State model use. While most inghouse activities, and standard-setting.

97 98 . Use of Models for Water Resources Management, Planning, and Policy

PROCEDURE USED IN CONDUCTING THE OTA STATE MODELING SURVEY

OTA surveyed State agencies responsible for the 2. Identify the most important problems and supply and quality of freshwater resources in June needs associated with water resource model 1980 to determine the extent of their current and maintenance in your State, and suggest op- potential water resource model use. State person- tions available to the Federal Government to nel were asked to identify major problems facing assist your State. the States in using models and Federal policy op- 3. Summarize reasons models are or are not used

tions to improve State model use. by your State. Consider the reliability and credibility of models, and human/institutional The survey was divided into two major sections. problems. Suggest options available to the The first assessed existing and potential State model Federal Government to assist your State in use in four major water resource areas: 1 ) surface model use. water flow and supply; 2) surface water quality; 3) ground water; and 4) economic and social con- Surveys were sent to State agencies responsible cerns. These areas were further divided into a total for both water quality and water supply concerns of 33 water resource issues. * Model use for each in each State. Since these responsibilities often rest of these issues was assessed for three different deci- with different State agencies, surveys were sent to sionmaking functions: 1 ) operations and manage- different agency contacts for water supply and water ment; 2) planning and policy; and 3) other (pri- quality issues. Names of key agency contacts were marily research). The respondents were also en- suggested by the State water resources research couraged to provide additional information on the institutes. role of models for each of the 33 water resource Six surveys were sent to each State agenc con- issues—e. g., the specific regulations for which the y tact (two contacts from each State)—a total of612 model is applied. Detailed results of this portion surveys. Each contact was asked to circulate these of the survey are compiled in appendix E. surveys among the agency personnel familiar with The second section of the survey posed three the use of models in the State for the 33 listed water broad questions on State model use: resource issues. Most of the surveys returned were submitted independentl by individual agency per- 1. Identify the most important needs associated y sonnel; some of the States, however, returned a sin- with water resource model development in gle response that had been circulated throughout your State, and suggest options available to the agency. the Federal Government to assist your State. All 50 States and the District of Columbia re- *A discussion of the modeling tc( hniqucs used to analyze each of turned completed surveys. However, the number thr fbur major rcsoutx c areas, and a review of the prohlcrns and mmlcl- ing ( apahil I t ics MS(X iatcd w lth [’w h of t h[’ 33 water r{’sour( c. issues, of surveys returned from each State varied from is prc’scntcd in ( h, 6 one to six. A total of 103 surveys were returned.

TRENDS IN CURRENT AND POTENTIAL STATE MODEL USE

Forty-eight States currently use water resource use only a few of the many models available—pri- models. Collectively, the States employ these mod- marily those based on well-established modeling els to address problems for all 33 identified water techniques like wasteload allocation or ground water resource issues. However, it is clear that most States supply models. Ch. 5—Use of Models by State Governments ● 99

The majority of States use models for less than quality issues. One of them, wasteload allocation, 10 resource issues, and 14 States (28 percent) use is the issue for which the greatest number of States them for five or fewer resource issues. Only one- indicated current or potential model use. While fifth of the States use models for more than 15 most States do not often employ models to assess issues (see table 5 and fig. 7). water quality problems, the few problems that have been studied most—e. g., wasteload allocation and In contrast to their current model use, a majority erosion/sedimentat ion— are widely analyzed using of the States identified potential uses for models in models. States tend to be frequent users of flow and more than 20 of the 33 water resource issues. Nearly supply models, in part because Federal agencies one-fourth of the States indicated that they could have been active in developing and applying them. use models for over 30 issues. These statistics indi- The Corps of Engineers and the U.S. Geological cate that although models are currently used for Survey (USGS) actively assist States in modeling a limited range of issues, State offcials see increased efforts for flood forecasting and control, drought model use as important for expanding State roles and low-flow forecasting, streamflow regulation, in water resources management, planning, and pol- domestic water supply, ground water supplies and icy (see fig. 7). Large discrepancies between existing and potential model use can be highlighted by ranking each of the 33 resource issues according to the percentage of States indicating current or potential model use. * Table 6 lists the States’ top 10 existing and potential water resource modeling uses, and figures 8-11 illustrate the percentages of States indicating current and potential use of models for each of the 33 water resource issues. These data indicate several trends: surface water flow models are currently the most widely used—5 of the 10 top-ranked resource issues are surface water flow issues. For ground water issues as well, supply and flow models rather than quality models receive the greatest amounts of current use. Three of the top 10 issues, however, are surface water

*These rankings are obtained for each resource issue by totaling the percentage of States using models to address that issue over the three specified decisionmaking functions (operations and management, planning and policy, and research). This combined number better reflects model use for each issue than percentages reported for any one decisionmaking category. A State may use sei’eral different models for the same issue—one for planning and policy, one for operations and management, and another for research.

Table 5.—Number of States Indicating Existing or Potential Model Use

Number of issues Existing Potential 0 through 5...... 14 2 6 through 10...... 14 Photo credit: Environmental Protection Agency 11 through 15...... 12 8 Water quality concerns, and the models used to analyze 16 through 20...... 5 7 them, are increasingly important to State agencies. While 21 through 25...... 3 9 only 3 of the States’ 10 most important model use areas 26 through 30...... 2 8 are currently water quality issues, OTA’S survey of State 31 through 33...... 0 12 officials shows that 7 of the 10 top water modeling areas SOURCE: Office of Technology Assessment, are expected to involve water quality in the future 100 . Use of Mode/s for Water Resources Management, Planning, and policy

Figure 7.—Number of Water Resource Issues for Which States Indicated Current or Potential Model Use

5 10 15 20 25 30 35 5 10 15 20 25 30 35 5 10 15 20 25 30 35 1

Ala. o Alas. La. 21

Me.

Ark. Mass. Okla. 29 31

Calif. Md. Pa.

Colo. Mich. R.1.

Corm. Minn. S.c. 3 1 32 0 Del. Miss. S.Dak. 32

D.C. Mo. Term. 33

Fla. Mont. Tex. 28

15 Ga. Nebr. Utah 14 33

Hi. Nev. 33 5 Ido. N.H. Va. Po Ill. N.J.

N.Mex Ind. 33

N.Y, Iowa 29

Wyo. Kans N.C. 33

The number of water resource issues for which States currently use models.

The number of water resource issues for which States could potentially use models.

SOURCE: Office of Technology Assessment. Ch. 5—Use of Models by State Governments 101

Table 6.—Rankings of State Model Use for Ail Water Resource issues (top ten)

Existing Potential ● Wasteload allocation ● Wasteload allocation ● Ground water supplies and safe yields ● Conjunctive use ● Streamflow regulation . Drought and low-flow forecasting ● Drought and low-flow forecasting ● Impacts on aquatic life ● Flood forecasting and control ● Ground water supplies ● Conjunctive use { ● Waste disposal—ground water ● Impacts on aquatic life ● Agricultural pollution—ground water ● Erosion/sedimentation . Urban runoff ● Domestic water supply ● Erosion/sedimentation . Instream flow ● Accidental contamination of ground water

aTied for fifth place SOURCE: Office of Technology Assessment.

Figure 8.—Surface Water Fiow and Suppiy issues

Percent 100

80 67 67

Operations and 60 51 43 management 43 40 23 20 >. 0 f“

63 63 61 61 60 - 57 55 Planning and 45 policy 40

20 -

0 100 r

60 Other 40 t 35 20 22 20 ‘6

o Flood Drought Streamflow Instream Domestic Irrigated Off stream Water use forecasting ancf low regulation flow water agriculture use efficiency flows supply

Percent of States currently using models

Percent of States indicating potential model use

SOURCE: Office of Technology Assessment. 102 ● Use of Models for Water Resources Management, Planning, and Policy

Figure 9.—Surface Water Quaiity issues

Percent 100 r 60 - 67 69 Operations ~ - 55 55 and management 40 - 27

100 fanr L

100 r 60 t Other 60 t 40 - 27 25 23 22 25

(l Surface Urban Erosion- Salinlty Agricultural Airborne Wasteload Thermal Toxic Drinking water runoff sediment runoff allocation pollution materials water quality quality

Percent of States currently m using models Percent of States indicating potential model use

SOURCE: Off Ice of Technology Assessment. safe yields, and conjunctive use of ground and sur- responsibilities that States have acquired for meet- face waters. ing national clean water goals. Models have an important role in States’ compliance with numerous The characteristics of the top 10 resource issues sections of the Clean Water Act. for potential model use differ significantly from those with the highest current use. Instead of flow Many States stress the need for ground water and supply, most of the identified problems involve models because modeling techniques are often the ground and surface water quality concerns—7 out only method of determining the characteristics of of 10 are quality issues. Ground water issues also major aquifers. However, the lack of ground water stand out among potential model uses; States rank data—particularly for pollutant transport within five of the six specified ground water resource issues aquifers— severely limits the current use of these in the top 10. models. In general, deficiencies in data and lack of knowledge of physical processes are more serious One reason for the widespread potential reported constraints to the use of ground and surface water for surface water quality models is the extensive quality models than for flow and quantity models. Ch. 5—Use of Models by State Governments ● 103

Figure IO.- Ground Water Issues

63 61 61 57 57 60 - 53 Operations and management d.

20 - 0 100 r 60 - 73 71 71 67 59 Planning and 60 policy 40 -

20 -

0 100 r

Other 40 - 25

0 Ground Conjunctive Accidental Agricultural Waste Saltwater water use contami- pollution of disposal Intrusion supply nation ground water Percent of States currently m using models

_ Percent of States indicating potential model use

SOURCE: Office of Technology Assessment.

Large discrepancies between current and potential use for particular issues suggest that State-1evel model use is limited by some technical or institutional factor (inadequate data, lack of qualified personnel, poor reliability of the model itself, etc.). For example, 34 percent of the States currently use drought and low-flow forecasting models for operations and management, while 67 percent of the States indicate potential uses for them. Resource issue-specific assessments of the States’ current and potential model use appear in the section of this chapter entitled: “State Model Use in Individual

Photo credit: @ Ted Spiegei, 1982 Water Resource Issue Areas.

State and local water quality agencies have major responsibility for designing community wastewater treatment facilities to meet Federal requirements under the Clean Water Act. Much of the current use of models—and the perceived need for additional modeling capabilities—at the State level stems from Federal requirements for State action 104 ● Use of Models for Water Resources Management, Planning, and Policy

Figure 11 .—Economic and Social Issues

Percent

Operations and G. management t 41 40 - 35 27 25 25

20 - 8

100 r 80 -

Planning and 60 - 59 policy 40 -

20 - 14

100 r 80 t Other 60 t 4o1- 20 20 - 10 12 2 0 Water costs of cost/ DeveIop- Forecasting Social Risk/ Competitive Unified pricing pollution benefit ment use implications benefit water use river basin control implications management

Percent of States currently m using models Percent of States indicating potential model use

SOURCE: Office of Technology Assessment.

CONSTRAINTS TO MODEL USE

State agencies were asked to identify problems limitations; 3) lack of qualified personnel; 4) ac- and needs associated with model development, use, cess to Federal models; 5) reliability and credibility and maintenance in their States, and to recommend of models; 6) model standardization; 7) funding; ways to solve problems and meet State needs. The 8) maintenance; and 9) documentation. responses to these questions ranged from general comments, like ‘‘inadequate data’ or ‘‘lack of qual- Developing Models To Meet ified personnel, to very detailed descriptions of State Needs problems with specific models or programs. The following sections highlight trends encountered in Respondents frequently recommended that Fed- the responses, according to nine subject areas: eral agencies develop models to meet State needs. 1) developing models to meet State needs; 2) data Many of the respondents identified a need for sim- Ch. 5—Use of Models by State Governments 105 ple models. Comprehensive models with large data Several respondents suggested that a central, or requirements are of little use to States lacking the possibly a ‘‘national’ data bank was necessary. time, resources, or capability to operate them. The States also identified four other important, According to the survey, many models cannot though less frequently cited, data problems: be applied to local site-specific problems. Models ● poor access to Federal/State data banks; are often designed to simulate an area too large for ● no data processing (storage and retrieval) capa- State purposes. bility; ● duplication of State and Federal data collec- Data Limitations tion efforts; and ● The inadequacy of data was the most common- intensive data requirements of many models. ly identified factor inhibiting State modeling efforts. Not only does insufficient data constrain the devel- Lack of Qualified Personnel opment and application of models, but the use of unreliable data can produce inaccurate results. For The States have a severe shortage of personnel example, one respondent commented on the im- qualified to develop, use, or maintain models. This pact of using unreliable data for planning advanced limits State modeling efforts in many ways. For waste treatment plants (AWT): example, some States are unable to modify existing Federal models to suit their specific needs. Other Millions of dollars have been expended for AWT States report that their lack of modeling expertise based on models which had an inadequate data causes an overreliance on contractors to develo base and the resulting treatment levels required p may or may not have been beneficial compared and apply models. to the costs. Part of the problem is due to the prevailing salary Many of the respondents noted that the reliability scales for State employees, which make it difficult and credibility of models is only as good as the in- to attract and retain qualified personnel. However, put data. most States did not propose supplemental Federal funding, but strongly recommended increased tech- The majority of comments concerning data were nical assistance and training by Federal agencies. general, often simply citing ‘‘insufficient data’ or “lack of data. The specific responses, however, One respondent wrote the following about the fall into several categories: need for training in his State:

● lack of data for specific stages of modeling (i.e., The main problem of model implementation in development, calibration, verification, etc.); Indiana is training. The Federal Government should provide the States with low-cost, applica- ● lack of data for specific issues (i. e., ground tion-oriented training opportunities . . . . water supply, nonpoint source pollution); ● outdated and poorly maintained data bases; Training was considered a high priority by the re- and spondents, second only to data needs. Specific con- ● unreliable or inaccurate data (e. g., data sam- cerns about training fell under three categories: pled at the wrong time). ● general education for management-level deci- Although the States rely on Federal agencies to sionmakers to understand and appreciate supply a substantial part of the needed data, they models; are and expect to be taking the major responsibil- ● advanced training for technical personnel to ity for data collection. The major obstacle in meet- develop, use and maintain models; and ing the States’ data needs is insufficient funding. ● recommendations for specific courses, e.g. , Along with funding problems, a shortage of man- training to use the Environmental) Protection power was another frequently mentioned factor lim- Agency’s (EPA) Stormwater Management iting data collection. Model. 106 ● Use of Models for Water Resources Management, Planning, and Policy

Although a few States requested funding for tional clearinghouse was also recommended by training, the majority of the States currently rely many respondents as a good method to make mod- on federally conducted training programs. The els available to the States. These centers would in- workshops and seminars held by the Corps of Engi- ventory available models and provide descriptions neers’ Hydrologic Engineering Center (HEC) and to potential users. The clearinghouse could also pro- USGS were praised by many respondents. One re- vide computer programs and documentation to spondent said: users. Respondents also suggested that a clearinghouse could serve as a center of technical ex- There is only a handful of people in this State, pertise, model maintenance, and quality control. including the USGS, who can use this type of model (2 D—ground water flow model). The training courses in Denver (sponsored by USGS) have Reliability and Credibility of Models been invaluable to us. Many of the State respondents pointed out that The States identified a need for technical assist- the reliability and credibility of models strongly in- ance at all stages of the modeling effort, from devel- fluences their use. Part of this influence is due to opment to maintenance, throughout the range of user perceptions. As one respondent stated, “Past water resource issues. Most comments were gener- experience with awkward models can impede future al, like ‘ ‘State needs model expertise assistance development. On the other hand, another re- (Federal) to expedite solutions. ” Other States ex- spondent wrote, “As we use the one model we pressed more specific technical assistance problems, have, and gain some experience, the reliability and e.g., “a lack of technical personnel at regional EPA credibility increase. levels to review and assist the State in model main- State respondents also recognized deficiencies in tenance, or ‘a strong technical assistance program technically measurable aspects of model reliability, in ground water modeling technology is needed to in particular, model calibration and validation. provide the capability to establish flexible predic- Many respondents mentioned problems with the tive mechanisms in ground water contamination reliability of specific models—a typical comment cases, was, ‘‘current ground water modeling programs are not sufficiently sophisticated to model the com- Access to Federal Models plex situation (especially the ground water-surface water interface) in this State. An important modeling problem common to many States is the difficulty of obtaining informa- The following concerns were reported as factors tion on or access to Federal models, data, and tech- affecting the reliability and credibility of models at nical assistance. The States rely heavily on the Fed- the State level: eral Government to supply such services to them; ● the degree of uncertainty in results is not com- improving access to these services represents per- municated for many models; haps the most easily realizable opportunity for the ● the reliability of many models has not been Federal Government to contribute to State model- established through repeated use; ing efforts. ● many model parameters are of questionable A majority of the comments on accessibility cen- accuracy; tered on the need for information about and access ● assumed values or calculations are sometimes to state-of-the-art Federal models. Generally, States used in the place of field data; are either unaware of, or unable to obtain, models ● the state of the art, in some cases, is not ad- and data to help them solve specific problems. vanced enough to provide reliable models; ● some decisionmakers are cautious about model A periodic report or newsletter was suggested as use due to a past history of inappropriate use; a means of informing States about Federal model- and ing activities. Alternatively, the State water re- ● model development has been overemphasized sources research institutes could provide a means in the past, to the detriment of calibration and of transferring information within each State. A na- validation. Ch. 5—Use of Models by State Governments . 107

Although comments on model calibration, verifi- adapting existing models (mainly Federal), and cation, and validation were not numerous, most have little or no funds available to develop models of the responses had a common theme: the States independently. Several respondents suggested that have an insufficient amount of time, resources, and coordinated Federal-State modeling efforts might data to perform these functions. improve the cost effectiveness of modeling. Specific comments included: The respondents also reported that funds are needed for: . some Federal agencies have encouraged the use of some models without adequately cali- ● computer equipment; brating or validating them with field data; ● testing and validating models; ● Federal agencies should devote more attention ● data collection; and to parameter estimation and testing model sen- ● personnel and training. sitivity; and . more comprehensive data sampling program Model Maintenance is needed for improved validation, and estimates of model accuracy should be developed From the States’ perspective, model maintenance and provided. is a minor problem. As most of the models they

use are federally built, they rely primarily on Model Standardization Federal agencies to maintain them. States generally seek assurance that Federal agencies will maintain Various suggestions were given for Federal ac- the models they have developed, and will advise tions to standardize the modeling process: States of revisions and modifications. ● develop standard procedures for model use A few respondents suggested funding States to (e.g., for determining wasteload allocations); maintain needed models if Federal agencies are un- ● develop standard procedures for model calibra- able to do so. One State cited intermittent fund- tion; ing for model maintenance as a problem. Several ● establish guidelines to govern technical devel- respondents recommended seminars as an effective opment of models; and means of informing States of model revisions or ● coordinate Federal data collection efforts to modifications. assure standardization and quality control. When models and model use procedures are not Documentation standardized, discrepancies can result if different models are used for the same purpose. One re- Few respondents reported problems with inade- spondent noted that several State and Federal agen- quate model documentation. The few that did typ- cies use different models to analyze the same prob- ically made a general comment, citing poor docu- lem—e. g., setting discharge standards. Coordina- mentation as ‘‘a barrier to model use. tion is needed to avoid conflicting results. Specific comments included: Funding ● user’s manuals are not written for the average user; Many respondents reported that low funding lev- ● documentation is not provided for modifica- els limit State modeling efforts. A few States re- tions in models; and ● ported that models were not used at all due to low lack of documentation leads to uncertainty funding. States generally use available funds for about the validity of model results. —.

108 Use of Models for Water Resources Management, Planning, and Policy

STATE MODEL USE IN INDIVIDUAL WATER RESOURCE ISSUES

Surface Water Flow and Supply Issues

Flood Forecasting and Control Flood forecasting and control models are widely used by State agencies. Most States that indicated a need for flood forecasting models (57 percent of respondents) currently use them for both operations and management decisions (43 percent) and planning and policy (45 percent). Some additional States rely on Federal agency modeling efforts to supply information needs in this area.

Major uses reported for these models include: 1) delineation of flood-prone areas and estimates of potential flood-related damage; 2) evaluation of existing spillway and dam adequacy (under the Na- tional Dam Safety Program); and 3) planning/design and operation of flood control facilities. In- creased emphasis on nonstructural flood control— e.g., improved flood plain management—in State flood control strategies has made models that delineate flood plains and evaluate the impacts of land-use changes on flooding patterns increasingly important to State efforts. A number of States reported a need for flood forecasting and control models that can analyze small watersheds.

Federally developed models for flood forecasting Photo credit: @ Ted Spiegel, 1982 and control are widely available to the States. Those Ruins of an apartment building in Johnstown, Pa., testify most frequently mentioned in survey responses to the destructive power of raging floodwaters. State agencies widely use flood forecasting and control were flood control models developed by the Soil models to assess the probable extent of flood Conservation Service and a series of models inundations and to route flows in ways that minimize developed by HEC. The effectiveness of the Corps actual flood damages of Engineers’ training program for these models has been a major factor in promoting their use at the State level.

Results from the OTA survey of Federal agencies indicated that model-based information on flood forecasting and control is distributed to State authorities by the National Oceanic and At- mospheric Administration, USGS, and the Federal Emergency Management Agency. Ch. 5—Use of Mode/s by State Governments ● 109

Drought and Low-Flow Forecasting Offstream Use

Slightly fewer than half of the States use models In many areas of the country, current stream- for forecasting droughts and low flows, but many flows and ground water reserves are insufficient to States acknowledged that models could be used sustain the large withdrawals required for agricul- more extensively. Forty-seven percent of the re- tural, industrial, and domestic uses. Projected spondents saw potential applications in operations growth in offstream demand for mining and general and management, and 63 percent in planning and economic development will increase conflicts be- policy —the highest reported for any surface water tween instream and water quality requirements on flow issue area. States in every region of the Na- one hand, and offstream withdrawals on the other. tion are concerned with drought and low-flow con- Few States currently use models to analyze off- ditions. While Western States reported use or po- stream uses. Those that do, concentrate on plan- tential use of these models to allocate water and ning and policy for projecting future use. Only one estimate the capability to meet demands, the signifi- State specifically mentioned planning, managing, cance of flow to water quality and wasteload alloca- and operating offstream facilities as an area present- tions has expanded the potential use of models ly involving the use of models. However, nearly throughout the country. Eastern States, in particu- half of the surveyed State officials indicated poten- lar, emphasized wasteload allocation in discussing tial use for offstream models. Determining the avail- potential applications for low-flow models. ability of water for hydropower, mining, and indus- A number of Federal agencies provide appropri- trial uses was considered a future area for model ate models for State use—respondents identified use, particularly in the context of comprehensive those of the Corps of Engineers, the National resource management. Eastern States as well as Weather Service, and the Soil Conservation Serv- Western States were concerned with offstream uses. ice. Federal agencies also supply States with model- generated information— several States mentioned Irrigated Agriculture USGS in this connection. In addition, the National Increasing conflicts with domestic water supply Weather Service provides low-flow forecasting for and instream flow needs necessitate sophisticated the States. planning and monitoring to ensure maximum benefits from irrigation water. State agencies employ Streamflow Regulation models to determine current and future supplies Models for streamflow regulation are currently and demands, and to determine optimal irrigation used by more than half of the survey respondents; schedules to aid farmers in conserving water. Such approximately the same percentage of States iden- models are currently used in about one-fifth of the tified potential uses for these models. The State surveyed States; slightly over twice as many States survey showed greater present use of streamflow reported a potential for model use. Potential uses regulation models than for any other surface include assessing both quantity and quality of sur- water flow issue. The survey also suggested that face water, as well as the effects of irrigation on these models are now employed by most of the ground water levels. Future uses for irrigated agri- States where officials have identified some use culture models include determining water rights, potential. water demands, and stream diversion.

Respondents identified a broad spectrum of ap- Domestic Water Supply plications for such models, including inter- and intra-State water distribution, reservoir operations Domestic water supplies have not kept pace with and dam safety, low-flow effects on wetlands, waste growing demands. In many localities, supply, treat- assiznihtion capacity, flood plain management/ ment, and distribution systems are inadequate, re- flood insurance, and fishery management below sulting in shortages and reduced water quaiity. dams. Comprehensive management for conservation, and 110 . Use of Models for Water Resources Management, Planning, and Policy multiple-objective planning, will become increas- Under 20 percent of the States surveyed currently ingly necessary as further growth occurs in water- use models in this area, although close to half indi- sport areas. cated potential uses for such models. State use focuses on models for predicting demand, and basic Current use of models by States focuses on pro- water accounting models similar to those used in jecting present and future supplies and demands, determining available supplies for agricultural, and designing supply systems to meet futur~ de- domestic, and other offstream and instream uses. mands. Slightly under one-third of those surveyed Greater existing and potential use was reported for use water supply models. Approximately twice as planning and policy purposes than for operations many indicated potential for model use, primarily and management. for assessing the relationship between water supplies and water quality requirements. A few States indicated a need for models to analyze the efficiency Surface Water Quality Issues of existing distribution systems. Urban Runoff Instream Flow Needs State officials reported high potential for model use to determine water quality problems stemmin,q Models for assessing instream flow needs serve from urban runoff, despite low levels of current use: a variety of purposes at the State level. Their use Two-thirds of the States saw continuing or possi- in planning and policy to meet instream flow needs ble future uses for such models in planning and for fisheries, recreation, and hydropower was policy analyses, and 55 percent envisioned uses for reported by 37 percent of the States—an additional operations and management decisions. Several 24 percent indicated the potential for such use. States suggested that the credibility of existing Fifty-five percent of the States acknowledged a models has limited their use. potential need for operations and management models, although only 12 percent currently use such The comprehensive planning provisions of sec- models. tion 208 of the Clean Water Act figure largely in State reports of existing and potential uses for ur- Instream flow models are becoming increasing- ban runoff models. Models are currently used to ly important as tools for setting minimum instream develop control measures; to plan, construct, and flow requirements. The models have further appli- maintain storm overflow facilities; and to research cation for meeting water quality standards and allo- and predict local urban runoff problems. Problems cating water. A few States cited data limitations as of site-specific adaptability and excessive complexity constraints to current use. Assistance in using these in current models were mentioned by a number of models is supplied by the Fish and Wildlife Serv- respondents. Respondents indicated that simple ice’s 1nstream Flow Group, the Corps of Engineers, models for site-specific calculations could increase and USGS. model use in this area, even though such models may not be suitable for complex runoff problems. Water Use Efficiency and Conservation Little is currently known about the extent to Erosion/Sedimentation which demands for water could be reduced through A number of States indicated the need for im- the use of conservation techniques or improved proved erosion/sedimentation models as a priority management and planning. However, potential in water resource management. Of the State re- benefits in reduced expenditures for supply, treat- spondents, 53 and 69 percent saw potential uses ment, and distribution systems were sufficient for for these models in operations/management and one-fourth of the States to indicate a potential use planning/policy, respectively—approximately 2 for models in researching these problems. This rep- times the current level of use. resents the greatest State interest in models for research purposes among all surf’ace water resource Many States reported current and potential mod- issues. el use under section 208 of the Clean Water Act. USGS and the Soil Conservation Service were re- rently use them for operations and management peatedly cited as providing models or working joint- decisions. Potential uses include: 1) determining ly with States to determine erosion and sedimenta- the ecological benefits of salinity reduction; tion effects. 2) implementing State ground water laws; 3) monitoring effects of pesticides and residuals; and State officials reported a wide variety of poten- 4) monitoring inland streams receiving brines from tial uses for erosion/sedimentation models; among saltwater sources. these are evaluating erosion control measures, determining canal and reservoir sedimentation rates, Agricultural Runoff evaluating irrigated and nonirrigated agricultural land uses, and planning for urban development. One-third of the States currently use agricultural runoff models for planning and policy, and nearly double that figure-57 percent—anticipate poten- Salinity tial uses. A number of States use models in connec- Salinity models do not appear to have a high pri- tion with section 208 of the Clean Water Act; others ority in State-level water resource management. specified future uses in planning and regulation of Less than half the State respondents identified po- animal wastes as well as in developing and imple- tential uses for such models, and only 6 percent cur- menting fertilizer and pesticide management plans. 112 . Use of Models for Water Resources Management, Planning, and Policy

Concern over the effects of agricultural runoff Thermal Pollution is reflected in actual and potential model use State water resource professionals reported that reported by States for research in this area. While available thermal pollution models are simple and only 8 percent of State respondents presently use accurate. About one-fourth of the surveyed States agricultural runoff models for operations and man- reported current use of such models, and about half agement decisions, 14 percent use them for re- of the respondents recognized potential uses for search, and 27 percent identify future research them. A number of States noted that all necessary potential for such models. thermal modeling under section 316(B) of the Clean Water Act is performed by power-generating or Airborne Pollution other industries, and is merely reviewed at the State Several of the comments indicated that some re- level. Others cited the Corps of Engineers, EPA, spondents misinterpreted this question. These re- and USGS as providing thermal modeling services spondents may have identified model use for State for States or in conjunction with State efforts. air pollution control, rather than for the specific purpose of determining the effects of airborne pollu- Toxic Chemicals tion on water quality. However, two States identi- Many States identified the development of mod- fied potential use of models for acid rain abatement. els to deal with toxicants as a top priority, with significant potential for future applications. As with Wasteload Allocation other recently recognized problems, about one- fourth of responding States identified a need for States use models extensively for determining such models in research, although few of the re- wasteload allocations. Two-thirds of the State spondents currently use them for any purpose. Po- respondents indicated present use for operations tential uses, both for operations/management and and management decisions, and 57 percent re- policy/planning, were identified by 55 percent of ported current use in planning and policymaking— the surveyed officials. more than for any other water resource-related purpose. Survey responses suggested that the relatively Respondents indicated that models are needed long history of model use in this area has made these for determining sources of toxicants, toxicant models widely available to States. Most States that transport and removal mechanisms, and for setting recognize potential uses for these models are pres- toxic chemical effluent standards. Some States iden- ently using them. The ubiquity of wasteload alloca- tified data availability as a limiting factor in mod- tion problems, and the expanded State role in water eling. pollution control, has contributed to widespread wasteload allocation model use. Model use was spe- Drinking Water Quality cifically mentioned for implementation of sections About half the States reported potential uses for 201, 208, 303, and 402 of the Clean Water Act. drinking water quality-related models, primarily to Many States, however, stated that these models assist in setting standards required under the Safe need refinement. Further validation of reaction Drinking Water Act. States also noted uses for im- rates and other necessary parameters, standardiza- proved models in determining the effects of waste- tion of models for different geographic regions of water discharges on drinking water quality, as well the country, and evaluations of the magnitudes of as for specific problems such as the effects of min- error in predictions, were among the improvements ing and low flows. A small number of States indi- suggested. Several States also identified the need cated that these models were of high priority; fewer for standard wasteload allocation models for the than one-fifth of the States indicated that they are following purposes: evaluating the effects of currently used. discharges into nontypical streams (swamps, estuaries, and intermittent streams), designing Water Quality Impacts on Aquatic Life standard waste treatment facilities, and determin- Several States stressed the need for further re- ing the need for advanced waste treatment. search and improved modeling techniques to gage Ch. 5—Use of Models by State Governments 113 the effects of changes in water quality on aquatic frequently; however, ground water supply model life. Credibility problems of current eutrophication use was equally evident for Eastern States. models were specifically mentioned. Survey com- Ground water supply models are presently em- ments suggested that improvements to aquatic life ployed by most of the States that reported some use impact models are of major concern to respondents potential; however, many States place a high pri- throughout the country. ority on improving these models. The lack of his- Sixty-nine percent of surveyed State officials torical aquifer performance data and the extensive identified potential application for these models in current data requirements of ground water models planning and policymaking; 55 percent identified were repeatedly cited as hindering State modeling future operations and management uses—in both efforts. cases about twice the existing level of use. Officials identified a variety of uses for aquatic life impact Conjunctive Use of Ground and Surface Water models, including evaluating permit applications, A higher percentage of survey respondents re- pollution control program planning, and compre- ported potential uses for models of the interaction hensive basin planning.

Ground Water Issues Ground Water Supplies and Safe Yields Over half the surveyed State personnel indicated use of models for determining ground water supplies and availability—the highest reported ground water-related model use. Many acknowledged use of USGS models and modeling expertise in developing ground water modeling programs. As might be expected, the use of such models by Western States in determining water rights was mentioned

Photo credits: @ Ted Spiegel, 198.2 Lake Tahoe, Nev., has long been billed as one of the world’s clearest bodies of water. Rapid development along shorelines, however, has greatly increased the flow of nutrients into the lake, accelerating natura{ eutrophication rates, creating nuisance algal growths, and endangering Tahoe’s ecological balance. Models have been used both to assess the effects of development and to evaluate the effectiveness of centralized sewage treatment in preventing the eutrophication process. In underwater labs above, University of California biologists and hydrological scientists use radioactive trace elements to monitor nutrient levels in the water. Meanwhile, crews build sewage transport facilities to divert wastes around Lake Tahoe for treatment and release in less sensitive areas 114 ● Use of Models for Water Resources Management, Planning, and Policy — ———

between ground water and surface water than for are primary limitations on States’ abilities to model any other ground water-related issue. Such models the spread and effects of pollutants to ground water are valuable for developing comprehensive basin from waste disposal sites. Limited understanding plans and for comprehensive water supply manage- of the reactions and diffusion of pollutants in mixed ment. Over 35 percent of the surveyed States cur- geological formations, and deficiencies of data for rently employ conjunctive use models—after supply validation purposes, were cited as specific problems. and safe-yield models, they are the most extensively While potential uses were reported by a high pro- used model for ground water management. Some portion of State officials-71 percent for planning States reported using models developed by USGS; and policymaking, 59 percent for operations and a number of others observed that the lack of field management decisions— these models are currently data constitutes a bottleneck to using these models. used by only one-fifth as many States. Anticipated uses include determining infiltration from sanitary Accidental Contamination of Ground Water landfills and mine waste disposal. Although over half the States indicated poten- Saltwater Intrusion tial for future use of models that predict the spread of contaminants in ground water, fewer than 10 Several States indicated that models for deter- percent currently employ them. Gaps in current mining saltwater intrusion to ground water supplies knowledge about the behavior of contaminants in are water resource management priorities; how- some types of ground water systems and data limi- ever, interest is naturally limited to coastal areas tations upon the construction and validation of such and States with major inland saltwater bodies. models hinder more widespread use. Survey re- The acquisition of sufficient data to verify such spondents envisioned such future applications as models was repeatedly cited as a significant need. determining effects of various pollutants and State officials envisioned several management uses requirements for control measures, devising warn- for these models, in particular establishing recharge ing systems for the public, and predicting longer areas, as well as determining acceptable pumping term contamination. rates and designing well fields. Agricultural Pollution to Ground Water Economic and Social Issues Determining the effects of agricultural pollutants on ground water is also a modeling area where re- Effects of Pricing on Use ported potential for State-level use is high, although Models that evaluate the effects of pricing on a low percentage of States currently use models. water use were seen as having potential planning Seventy-one percent of the surveyed State officials and policymaking uses by 59 percent of the State saw potential uses for such models in planning and survey respondents. Respondents referred to com- policymaking, and 57 percent envisioned operations prehensive planning efforts under title III of the and management uses— current uses amount to less Water Resources Planning Act and section 201 fa- than one-sixth of these potential use levels. The of- cilities planning under the Clean Water Act as areas ficials specified potential uses for these models in in which models are needed. Some States suggested section 208 planning, determining effects of various that current models are not precise evaluation tools, contaminants and corrective measures, planning“1-l and that their importance may be limited to places allowable point source pollutant loads, and supple- where strict conservation and reuse laws apply. mental monitoring for regulatory purposes. A num- Models are currently used by a small proportion ber of States indicated that data on pollutant move- of surveyed States, primarily in planning and re- ment is a limiting factor in model development and search. use. Costs of Pollution Control Ground Water Pollution From Waste Disposal Slightly fewer States indicated a need for models Survey respondents indicated that lack of data to evaluate pollution control costs than for most and poor understanding of ground water chemistry other types of social and economic modeling. Su~- Ch. 5—Use of Models by State Governments . 115 gested potential uses include assessing the effects adequately modeled. A number of States indicated of alternative waste treatment strategies on firm that improved models for cost/benefit analysis behavior, and determining the impacts of pollution would be highly desirable, and one respondent spec- control costs on individual industries. At present, ified a need for a combined hydrologic/economic such models are used in only a few States. model for cost/benefit studies.

Cost/Benefit Analysis Regional Economic Development Implications Use of cost/benefit analysis models for planning Models for evaluating economic implications of and policymaking was envisioned by over half the water resources development and policy are used State officials; 23 percent of those surveyed current- by States in the context of planning efforts under ly use such models for planning. Some current users section 208 of the Clean Water Act and title III of noted, however, that models evaluating the cost ef- the Water Resources Planning Act. Slightly fewer fectiveness of alternative actions are more applicable than one-half of the surveyed State personnel pre- than cost/benefit models. Several respondents con- dicted future uses for these models; 22 percent indi- sider the cost/benefit concept too subjective to be cated current planning uses. Officials mentioned .—

116 ● Use of Models for Water Resources Management, Planning, and Policy such specific uses as predicting population and ty analysis, flood management, and toxic waste economic growth in water-short areas, comprehen- management. Slightly fewer than half foresaw fu- sive river basin planning, and determining the ef- ture planning and policy uses for these models in fects of ground water depletion. their States; 10 percent currently employ them.

Forecasting Water Use Competitive Water Use Forecasting water use with models was con- Fifty-nine percent of the surveyed officials in- sidered possible at the State level by 59 percent of dicated the possibility of future planning and policy- survey respondents; 31 percent currently use such making applications for models of competitive water models for planning and policy purposes. Some use; one-fifth reported that such models are cur- States doubt the reliability of these models in their rently used by their States. A few States reported current forms, and suggested that existing data are that these models are a high priority for analytical inadequate to justify sophisticated model forecast- work. Reported potential applications include: ing. A variety of applications are projected for basinwide water supply planning, water rights de- improved models; ensuring that water quality terminations, and the evaluation of conflicts be- standards are not violated due to overallocation of tween water supply and water quality objectives. supplies, and evaluating existing laws regulating ground and surface water use were repeatedly men- Unified River Basin Management tioned, as well as simple projections of future Models for unified river basin management are demand. currently used by a greater percentage of States than any other socioeconomic model: one-third of Social Impact the survey respondents indicated that such models Relatively few States indicated a need or poten- are currently employed for planning and policy- tial use for social impact models. While one State making, and nearly twice as many foresaw future official suggested development of a general model use potential. State-level personnel mentioned such that could be calibrated to local conditions, little uses for these models as regional water supply plan-

State-level interest in such models was expressed, ning, integrating water quality considerations with and some respondents questioned their reliability. basin development, planning studies to evaluate different management options, and planning and con- Risk/Benefit Analysis trol of development. State officials reported a variety of potential uses for risk/benefit analysis models, including dam safe- Chapter 6 Modeling and Water Resource Issues Contents

Page Surface Water Flow and Supply...... 119 Introduction ...... 119 Types of Models Used in Surface Water Flow and Supply Analysis ...... 121 Water Availability Issues ...... 124 Water Use Issues ...... 128 Evaluation of Currently Available Surface Water Flow and Supply Models . . . . . 130 Surface Water Quality ...... 131 Introduction ...... 131 Types of Models Used in Surface Water Quality Analysis ...... 132 Nonpoint Source Issues ...... 134 Point Source and General Issues ...... 138 Evaluation of Currently Available Surface Water Quality Models ...... 141 Ground Water Quantity and Quality ...... 143 Introduction ...... 143 Types of Models Used in Ground Water Resources Analysis ...... 144 Ground Water Quantity Issues ...... 146 Ground Water Quality Issues ...... 147 Evaluation of Currently Available Ground Water Models ...... 151 Economic and Social Models ...... 152 Introduction ...... 152 Basic Analytical Characteristics ...... 153 Types of Models Used for Economic Analysis ...... 155 Other Social and Economic Analytical Techniques ...... 155 Economic and Social Issues in Water Resource Analysis ...... 156

TABLES

Table No. Page 7. Surface Water Flow and Supply Model Evaluation ...... 130 8. Surface Water Quality Model Evaluation ...... 142 9. Ground Water Model Evaluation ...... 151 Chapter 6 Modeling and Water Resource Issues —— —— —

Government agencies normally use water re- cantly with regard to levels of current knowledge, source models to address specific resource problems kinds of issues addressed, and types of models and under their jurisdiction. While most problems and levels of modeling expertise currently available. model applications have unique aspects, it is possi- Each is discussed in a separate section of the ble to generalize about the kinds of problems most chapter. frequently encountered in water resource manage- The first three subject areas deal primarily with merit — and the analytic techniques used to under- physical processes, and are described according to stand them. This chapter describes 33 of the Na- a common format: 1) introduction; 2) types of mod- tion’s most prevalent water resource issues, brief- els; 3) issues addressed; and 4) evaluation of cur- ly assesses the modeling capabilities associated with rently available models. Each subject-area model each of them, and evaluates the model types used evaluation follows a format that reflects the prob- to analyze them. Previous chapters have focused lems addressed, processes modeled, and mathe- on generic issues and problems involving water re- matical techniques most commonly used within source models; this chapter deals with specific water each scientific discipline. The last area, economic resource concerns and the capacity of models to ad- and social models, deals with the social science in- dress them. It is provided as a layman’s introduc- formation needed to support water resource deci- tion to the relationship between models and real- sionmaking. Models of social sciences processes dif- world water resource issues. fer fundamentally from those of physical processes, Water resource concerns can readily be grouped and are extremely diverse; consequently, a larger according to four major subject areas: 1 ) surface subjective component is involved in evaluating water flow and supply; 2) surface water quality; them. No formal evaluation of economic and social 3) ground water quantity and quality; and 4) eco models was undertaken for this study. nomic and social models. The areas differ signifi-

SURFACE WATER FLOW AND SUPPLY Introduction Water resource models are widely applicable to problems in policy, planning, operational manage- Managing surface water today virtually requires ment, and regulation of the Nation surface water the use of a wide range of computer-based analytical resources. Existing models are widely used to plan techniques, ranging from sophisticated models that and operational~ manage most water availability y and forecast the probable frequencies and extents of water use problems. Model use is not as common serious floods, to relatively simple computer models for policy and regulatory activities, partially because for simulating the operational characteristics of farm existing models are not well adapted to decision- irrigation systems. All of these models provide in- making in these governmental areas, and partial- formation to help assure that water will be available ly because such decisions have traditionally been when and where needed, or will not intrude when based more on qualitative than quantitative criteria. or where it is not wanted. Models permit the analyst to: 1 ) make reasonable predictiom of natural events, Models used to analyze surface water flow and and 2) estimate the favorable and adverse cose- Supply problems can be subdivided into two broad quences of man’s attempts to improve the reliabili- categories, for which both current model capabilities ty of’ freshwater production, distribution, and use and future promising roles are somewhat different. Syst ems. For each of the two broad categories-water avail-

119 120 ● Use of Models for Water Resources Management, Planning, and Policy ability and water use— four specific problem areas are discussed later in this section. Although these problem areas are not all-inclusive, they encom- pass the major surface water quantity problems facing the Nation. Each problem area is specific enough to permit discussion of successes and failures in the use of models, and development of recommendations for appropriate model uses. An evaluation table for the models used in each problem area is presented later in this chapter (see table 7). To introduce the modeling techniques that apply to surface water flow and supply issues, applicable model types are discussed below. Generally, the model types are not limited to one specific problem area—each model type may be applicable to several issues. References, keyed to over 30 model classes, are provided in appendix D to this report.

Availability of Water Water availability analysis-which encompasses but is not limited to the sciences of hydrology and meteorology —uses models extensively. While models are less frequently used in policymaking than for planning and management, numerous examples of model use for determining water availability can be cited throughout private industry and at all levels of government. In fact, a major problem in using models to analyze a given water availability problem is the difficulty of selecting—from among the plethora of available models—the most appropriate model for the problem at hand. Determining the availability of surface water requires analyses of the hydrologic cycle, typically including calculations of streamflow magnitude, duration, and frequency; and the temporal and spatial variations of these streamflow characteristics. A specific problem may require analyzing one or more of these characteristics at a single point along a stream—for instance, to determine the extent of a change the timing and distribution of streamflow; flood plain—or it may require coordinated analysis and to improve management of this increasingly at a large number of locations in a watershed (e. g., scarce renewable resource for a variety of beneficial to operate a series of multiple-purpose reservoirs). purposes. Certain types of human intervention in Solving problems of water availability, however, natural hydrologic processes can be modeled rea- requires more than understanding and modeling sonably well, but many types of modifications and the hydrologic cycle. Many problems arise because controls introduce conditions that may be too com- of the need to alter natural hydrologic processes for a plex to simulate or forecast accurately. In dealing variety of reasons: to reduce flood hazards; to with water availability problems, one must distin- reduce the risks of drought and low streamflow; to guish between the capability to model natural proc- Ch. 6—Modeling and Water Resource Issues ● 121 — — esses, and current capabilities to model the effects of a flood or drought, the magnitude of a flood peak, human management efforts on these processes. or even regional water use demands.

Water Use Watershed Process Models Models have been used less frequently to analyze Watershed process models follow the movement water use than to analyze water availability. Ex- of water from the time it reaches the Earth as pre- cept for agricultural irrigation needs in arid areas cipitation until it flows into a lake or stream, reaches of the Western United States, water availability has a ground water aquifer, or evaporates back to the historically been so much greater than water use atmosphere. Models used to describe the dynamics that there was little or no requirement for sophisti- of water over three distinctly different types of land cated analysis. Consequently, almost no effort was areas are described in this section: 1) watershed expended on developing models to analyze water simulation models, which describe the movement use. In recent years, however, increasing demand of water over large, nonurban areas; 2) agricultural for relatively large quantities of water—e. g., for soil/water interaction models, which are designed energy development—and the droughts of the to specifically address agricultural water problems; 1960’s in the Northeast and the 1970’s in the and 3) urban runoff models, which describe the Midwest and West, have stimulated the develop- movement of water through urban areas. ment of models for planning and operations/man- Watershed Simulation Models.—Simulation agement. Nonetheless, these recent developments models describing the movement of water over are not yet reflected in widespread adoption of water large, nonurban areas are used to estimate flood use models. peaks, low flows, and volumes of water available Water availability and water use also differ in to users. They are most useful where historical the kinds of information they require for model con- streamflow data are sparse or nonexistent. These struction. Most problems of water availability are simulation models are powerful planning tools that concerned with physical principles and relationships come far closer to replicating measured flows than that are reasonably well understood, and are conse- was previously possible. Four types of processes quently easier to model successfully, while most must be included in watershed simulation models: water use problems involve not only physical fac- 1) the movement of rainfall into and through the tors but also social and economic factors—many of soil; 2) ground water flow to streams (called base- which are less well understood. The lack of knowl- flow); s) the l0SS of water to the atmosphere from edge about interrelationships among economic, so- evaporation and evapotranspiration from plants; cial, and physical factors is compounded by a lack and 4) in colder climates, snow accumulation and of data on social and economic factors related to snowmelt. water use. Social and economic models are dis- Watershed soil/water process models are used to repli- cussed in more detail later in this chapter. cate water movement into and through the soil for: 1) estimating flood peaks during storm events; Types of Models Used in Surface 2) estimating water supply on an annual basis; and Water Flow and Supply Analysis 3) estimating low flows during dry periods. Cur- rent models are most reliable for estimating low Of the wide array of models used to analyze vari- flows and total annual runoff volumes, and less so ous aspects of surface water flow and supply, the (but still acceptable) for calculating short-term flows most important ones fall into two broad model and flood peaks. classes—process models and statistical models. Proc- ess models simulate or describe the flow of water During low-flow periods, except in very humid through a watershed or water body using known, climates, water enters streams primarily by seepage physical relationships. Statistical models use empir- through the soil profile or from aquifers. Most ically derived relationships—often with no inherent baseflow models do not use advanced ground water physical meaning—to estimate the probability of modeling techniques to estimate flow rates, but

8 + - [ 83 n - 82 - 3 122 ● Use of Models for Water Resources Management, Planning, and Policy rather use observed flow patterns during long dry periods as an estimate of ground water flow to streams. They are quite adequate for estimating baseflow during floods, and reasonably good for estimating low flows.

Evaporation from water surfaces and evapotransPira- tion from plants are modeled to simulate the soil- drying process. The drier the soil, the more precipitation will infiltrate and be stored during the next storm. The results are more reliable for watershed- wide average soil moisture than for specific locations within the watershed, but are difficult to validate because of the scarcity of field data. For areas where snow remains on the ground for more than about a month, the processes of snow accumulation on the ground and snowmelt in the spring must also be considered. Total runoff volumes from snowmelt can be simulated quite well for forecasting water availability during the following summer, but models are not very reliable for simulating snowmelt flood peaks (magnitudes are bad and timing is worse), because of the difficulty of predicting spring weather conditions. However, in areas where the snowmelt occurs relatively slowly, the models are adequate for most purposes. Agricultural Soil/Water Interaction Models.— Simulation models similar to the watershed process models described above have been developed to assist in agricultural water conservation. Four types of models are currently available: Soil/water process models are sometimes specialized to estimate moisture conditions in a small plot, rather than average conditions over an entire watershed. These P!ot--size soil/water process models are used for agricultural water management and land- use decisionmaking. This approach has potential for improving crop management decisions, but system design. Results from irrigation water demand these models are not yet very accurate. models are generally reliable for estimating average Models that analyze the effects of local climatic annual water use, but poor for estimating how use variation on @ant water use are valuable for allocating is distributed over the irrigation season. available water supplies. Acceptable results are ob- In areas where excess water is a problem, soil tained on an annual or seasonal basis, but estimates moisture can be reduced by subsurface tile or ditch of shorter term demands (less than 1 month) are drains to make the land more productive. Land unreliable. drainage models estimate flow rates for system design The extent and duration of the soil’s capacity to and residual field moisture conditions for cropping hold irrigation water for plant use has been modeled decisions. These models achieve adequate to good to assist in farm water management and irrigation results. Ch. 6—Modeling and Water Resource Issues ● 123

Urban Runoff Models .—Urban runoff models of flooding. The most accurate results from flood generate simultaneous flows from many small ur- inundation models are achieved when the stream flows ban watersheds, and aggregate them into flood between stable channel banks, and the least reliable flows for specified downstream points. These mod- estimates are obtained on broad flat flood plains els are sophisticated tools for urban flood plain where flows are deflected by small obstructions and management and for designing and operating are spread in random patterns from one event to urban storm-water control systems. They have re- the next. ceived widespread use over the last few years and Special channel routing models are used to deter- promise a great deal for the future. mine the downstream areas that would be inun- dated if a dam failed. The reliabilit of dam failure Stream Process Models y models is uncertain, because few historical records Stream process models begin describing the are available on the hydrologic conditions existing movement of water at the point where watershed at the time of failure. process models end— once the water enters a stream, lake, or reservoir. In this section, two topics Alluvial Process Models. —The dynamics of are discussed: 1) models that describe the flow of channel erosion and sediment deposition have been water through streams, lakes, and reservoirs, used described through modeling techniques. The re- primarily for flood control; and 2) models that de- sults, however, are approximate, and a great deal scribe the movement and erosion of sediments more research is needed to make these models reli- (called alluvial processes) within water bodies. able. Two important problem areas include reservoir sedimentation and channel erosion: Channel Process Models.—Channel process models describe the flow of water through streams, Re.sewoir sedimentation models have been developed lakes, and reservoirs. They are often used for reser- for determining the amount of sediment washed voir operations during flood conditions and for flood into a reservoir that is deposited on the bottom, thus plain management. In general, they provide very reducing its water storage capacity. These models reliable results when accurate information on chan- do not have the accuracy desired for estimating nel and flood plain geometry is available. The fol- useful reservoir life, unless supported by empirical lowing models are included in this category: relationships from reservoir surveys. F[ood channel routing models are used for operating Flowing water can erode the channels through flood control facilities or issuing warnings during which it flows and deposit sediment loads down- flood emergencies. These models provide quite reli- stream. Problem locations can be identified by able estimates of changes in flow depth and veloc- using channel erosion and deposition models, but the ity as water moves downstream in well-defined results are not reliable enough for channel design channels. However, the estimates are less accurate or maintenance management. for larger floods where streams overflow their banks, and are particularly unreliable where flows Statistical Models spread out over large flat areas. When causative mechanisms are not well enough When flows enter a lake or reservoir they increase understood to construct process models, or the ex- both water depth and outflow through spillways or pense of developing or using process models is not other outlet controls. Lake and reservoir routing mod- justifiable, statistical models are often used in their els are accurate enough to size spillways to ensure place. Statistical models can be used whenever dam safety and for controlling spillway gates to min- enough data are available to estimate the relation- imize downstream flood damage. ships between factors of interest—without having to understand the underlying physical processes. Flood plain management relies heavily on accurate mapping of flood hazard areas. Models can Three types of models are presented in this sec- estimate flood heights and—when combinecl with tion: 1) statistical flood models, which yield results accurate topographic maps—the geographic extent similar to combined watershed and stream process 124 Use of Models for Water Resources Management, P/arming, and Policy -— —.—. . models; 2) flood and drought frequency analysis, nual data generation models can generate annual runoff used for sizing flood control or water supply proj- sequences that match the size, probability distribu- ects; and 3) water use statistical relationships, which tion, and other patterns of historical flows for use are used to estimate demands for water. in determining reservoir capacity. The results are generally good for monthly, seasonal, or annual Statistical Flood Models .—Statistical models— time periods. simpler in approach than the process models dis- Another important use of statistical models is for cussed earlier—have been developed to estimate assisting reservoir design. By accounting for all in- flood flows and areas of inundation. These tools are flows (stream and precipitation) and outflows (evap- useful for structural design or reservoir operation oration, uncontrolled releases, and project water in situations where more sophisticated continuous delivered) over long time periods, capacity require- simulation models are not justified. Three common ments for designing reservoirs and rules for operat- approaches—flood formulae, regional flood for- ing them during dry periods can be determined. mulae, and unit hydrography models—have been Reseruoir water accounting models provide excellent re- extensively used. sults if reliable data are available to describe inflow Flood formulae are simple equations for estimating and storage volumes. flood peaks from watershed characteristics. They Water Use Statistical Relationships.—Water have been used for years to help design small struc- use demands (use as it would be if unconstrained tures, but can only be recommended for relatively by supply shortages) are estimated either from his- small projects. Much more reliable for structural torical data or simulation models. Two types of planning are regional flood formulcw. These equations models have been applied on broad regional scales: are derived statistically using historical data and can be used for estimating flood peaks on streams Regional water use relationships statistically estimate throughout hydrologically uniform regions. peak, annual, and seasonal variations in water use rates. Their results are generally adequate for esti- Another approach, called unit hydrography mode/- mating the volume of water needed over long peri- ing, is based on the assumption that a given amount ods, but not for estimating peak demands. of runoff from a given watershed will always result in similar flood patterns. These models have long Annual use generation models, similar to models that been used to establish flow patterns for designing simulate streamflow, have potential for generating flood control reservoirs. The results are reasonable estimates of monthly to annual water use. These for reservoir design to prevent flooding by a storm results may then be combined with supply estimates event of specified size, but less than desirable for for the same period to improve water supply reser- reservoir operation. voir design or operating procedures. However, reliable models of this type are not widely used. Flood and Drought Frequency Analysis.— Several approaches are available for estimating the Water Availability Issues frequency of occurrence of floods and droughts. The purpose of these models is to determine the econom- Flood Forecasting and Control ically optimal size of flood control or water supply Floods rank among the most prevalent of natural projects. The available statistical models provide hazards. About half of the Nation’s communities, reasonable to good results for most applications. and nearly 90 percent of its largest metropolitan Flow frequency models analyze historical series of areas, are located in flood-prone areas. Despite ex- flood peaks, flood volumes, or low flows to provide penditures of more than $13 billion for flood con- an estimate of the maximum or minimum flow trol over the last 50 years, flood damage continues magnitudes to be expected, on the average, no more to rise each year. Residential, commercial, and in- than once every 10 years, 100 years, or some other dustrial development in flood-prone areas outstrips period. The reliability of these models improves our ability to provide protection, while the econom- with longer record lengths. Once the statistical char- ic value of existing damage-susceptible property in- acteristics of streamflow have been determined, an- creases as well. Ch. 6—Modeling and Water Resource Issues ● 125

Available models and the hydrologic data re- Good hydrologic analysis on a microscale basis quired to operate them are generally adequate for requires considerably more data than macroscale flood control planning and management. Even in analysis; consequently, geographic consistency in situations where hydrologic records are not as ex- data on soil types, vegetation, land use, precipita- tensive as designers require, statistical methods and tion, and surface runoff is considerably more impor- digital simulation models provide sufficient infor- tant in microscale analysis. As a result, the models mation for designing flood control and protection being developed for microscale analysis frequent- structures. ly depend on the availability of spatial data bases— i.e. , sets of computerized ‘‘maps’ with a geo- Although there are isolated cases of design defi- graphically consistent set of data on an area’s physi- ciencies in flood control projects, most of the hun- cal characteristics. Although the needed data are dreds of existing projects function as planned. frequently available on printed maps, the effort re- When flood damage occurs in ‘‘protected’ areas, quired for digitizing and maintaining the data sig- it is generally not due to faulty flood forecasting nificantly limits widespread use of these models at or to failure to operate flood control projects prop- present. erly. Rather, damages occur because the flood magnitude exceeds the degree of protection provided Model use for the regulatory aspects of flood con- by the project. However, when flood magnitudes trol has been extensive in both flood plain manage- exceed the project’s protective capabilities, accurate ment and flood insurance programs. Two basic forecasting becomes essential for minimizing loss types of models—flood inundation models and flood even if it cannot prevent loss. A poor forecast of a frequency models—have been widely employed. flood exceeding the control structure’s capacity can Flood inundation models are used to delineate flood cause serious mismanagement, and greatly increase hazard areas. When properly used, the available the resulting damage. Improvement is needed in models are relatively noncontroversial. However, the accuracy with which flood characteristics are problems have occurred when the analysis is per- predicted once the event is under way. formed for part of a stream at one time and for adjacent parts at another time, with the result that While models and predictive methods for flood the flood hazard areas fail to coincide at the bound- control planning and management are generally aries of adjacent areas. Since the primary purpose satisfactory for design, engineering, and routine of this analysis is regulatory in nature—identifying operation of traditional areawide flood control struc- areas subject to flooding so that appropriate restric- tures, flood control planners are increasingly con- tions in use can be implemented—it is not surpris- cerned with nonstructural measures for reducing ing that even minor inconsistencies in flood hazard flood damage. Consequently, new needs for models area delineations are major sources of controversy. and data aimed at nonstructural approaches have arisen. Many of these measures are regulatory in A larger source of controversy has been the use nature, and frequently address areas considerably of statistical flood models to determine the magni- smaller than those associated with larger scale struc- tude of flood associated with a specified recurrence tural projects. As a result, many traditional flood interval (usually 100 years). Each of the half dozen control models are not suited for planning and man- or so major flood frequency theories (and the mod- aging nonstructural approaches. These traditional els based on them) produces somewhat different re- models are based on a ‘‘ macrohydrologic’ scale, sults in a given setting, even when the same data in which model assumptions and data requirements set is used for all cases. In some instances the dif-

are scaled to hydrologic analyses for relatively large ferent theories give considerably different results, watersheds. However, when these models are ap- so that estimates of the size of a 100-year flood, for plied to the ‘‘ microhydrologic’ scale, they are often instance, may vary by a factor of two or more. With fuuncl to be inappropriate, either because detailed that large a variation in flood magnitude, there is data are not available at the microscale level, or an attendant, but usually somewhat smaller, varia- because the macroscale assumptions are not consist- tion in flood hazard area—since the amount of land ent with conditions on the smaller scale. subject to development restrictions varies with the 126 Use of Models for Water Resources Management, P/arming, and Policy estimate of the 100-year flood magnitude. Flood enced in recorded history in a given watershed. frequency estimates at different points on the same Because of natural variation and differences in the stream using different models (or even at the same length of available hydrologic records in different point using different models) often produce different watersheds, the ‘‘drought of record’ in some water- results, causing a tremendous amount of confusion sheds is very severe—perhaps with an estimated re- and controversy. Since the differences are not due currence interval of 300 years or more—while in to error in calculation, but to fundamental differ- other watersheds the drought of record may have ences in the assumptions of the models, the differ- a recurrence interval of 20 years or less. ences are essentially irreconcilable. The need for When the drought of record is used as a design consistency was a major factor in the Water Re- standard, some facilities are inevitably underde- sources Council’s decision to recommend a uniform signed and others are overdesigned. Thus, while technique (or model) for use by Federal agencies failures of flood control structures are rare, serious in performing flood frequency analyses. That deci- inaccuracies in low-flow management facilities are sion has eliminated some, but not all, of the contro- relatively common. Although alternative methods versy. have been developed for calculating streamflow sequences of long duration based on statistical anal- LOW-FlOW and Drought Forecasting ysis of relatively short historical hydrologic records, Low streamflow is caused primarily by physical planners have been reluctant to accept designs phenomena, while droughts result from the joint based on statistical methods that differ substantially occurrence of low streamflow and high demand—a from designs based on the “drought of record. ” condition due to social and economic causes as well Considerably more work is needed on the use of as physical ones. Modeling capability for forecasting statistical methods for planning, designing, oper- and managing low streamflow per se is as highly ating, and managing low-flow control facilities. developed as for flood forecasting. However, from Public policy for dealing with low-flow problems the point of view of drought management, which has focused more on water availability y policy than requires an ability to modify both water availability on water use in low-flow periods—except with re- and water use, the available models are less satis- gard to competition among uses (irrigation, hydro- factory. electric power, municipal water supply), which will The major difficulty in forecasting low flows be discussed in the following subsection on stream- stems from problems in choosing appropriate sta- flow regulation. Little use has been made of models tistical procedures for determining how often to ex- for regulatory aspects of low-flow management, expect low flows of a specified volume and duration. cept where interstate compacts or judicial decisions Most of the theories used in hydrologic probability have forced governmental entities to apportion low analysis are based on the concept of independ- flow among competing users. In general, available ence—the idea that two or more “events’ are total- models seem to be adequate for these needs. ly unrelated to one another. In the case of low streamflow, analysts are normally concerned with Streamflow Regulation the quantity of streamflow during a specific period The Nation has invested billions of dollars in of time. Frequently, however, the specified period facilities to regulate streamflow for a variety of pur- is part of a more extended period of low flow pro- poses: to reduce flood damage; to generate hydro- duced by general climatological and meteorological electric power; to provide stable navigation chan- trends. For this reason, it is difficult to ascribe prob- nels; to provide dependable surface water supplies ability estimates to low-flow ‘‘events. for municipal, industrial, and agricultural uses; to Perhaps because of the difficulty of determining improve fish and wildlife habitat; and to provide low-flow probabilities, a common practice in plan- recreational opportunities. Federal agencies alone ning and designing facilities for low-flow manage- have constructed hundreds of structures that regu- ment has been to design for the ‘ ‘drought of rec- late streamflow for one or more of these purposes. ord, i.e., the most severe low-flow period experi- Thousands more have been constructed by other Ch. 6—Modeling and Water Resource Issues ● 127 — — governmental entities, private enterprises, and indi- short- and long-term operational management deci- viduals. Most of these facilities are passive; i.e., sions and plans. they require little, if any, operational management More recently, modeling capabilities for opera- (other than routine maintenance) to accomplish tional management of streamflow regulation struc- their intended purpose. Levees, ungated diversion tures have expanded to include mathematical op- structures, and small dams with ungated spillways timization models and—in a few instances—online, are typical facilities that require minimal opera- real-time models used for controlling major por- tional management. tions of a system’s operation. Some simulation Hundreds of these existing facilities, however, models have also been expanded to analyze eco- are not passive. They are large, complex structures nomic, institutional, and environmental factors. serving many purposes and requiring intricate However, data acquisition (particularly for real- daily, hourly, or sometimes even minute-to-minute time operation) and model calibration are substan- operational management to achieve their intended tial obstacles to widespread use of the models cur- purposes. Myriad conditions, criteria, and data rently available for large systems; many operating must be identified and evaluated each time an op- entities do not have sufficient computer capabilities erational decision is made. Some operational and personnel to use the most sophisticated models criteria are based on fixed conditions (e. g., those available for onsite operational decisions. that ensure the safety of the structure) while others are based on changing phenomena (e. g., current Instream Needs and future weather conditions). Operational management is further complicated in multipurpose Determining instream flow needs differs from projects because some purposes are competitive (a other water availability problems in that instream decision favoring one purpose has an adverse ef- flow needs are frequently linked to water quality fect on some other purpose), while others are com- rather than water quantity requirements. The two plementary (a decision favoring one purpose has most common purposes for establishing instream beneficial effects on other purposes). Operational flow requirements are to preserve and protect management problems are even more complex in aquatic and riparian ecosystems, and to comply watersheds where two or more multipurpose proj- with statutory, contractual, or institutional obliga- ects exist. In this case, decisions for each project tions to maintain the necessary streamflows. must be coordinated so that the projects themselves The common practice of specifying instream function in a complementary fashion. needs in terms of water volume dates back to the Over the past decade, computer models that give earliest days of water resource development in this the project manager much greater flexibility than country, when allocating water to meet these needs previously used fixed operating rules have been was labeled ‘‘low-flow augmentation. While it was developed. Thus, it is now feasible to model the recognized that many of the objectives of low-flow operation of single projects or large systems of inter- augmentation were related to water quality char- connected projects. acteristics rather than to water quantity per se, virtually all of the analytic techniques available for Many fixed operational rules have been replaced planning and managing strearnflow regulation were by models that permit day-to-day decisionmaking quantity oriented, that can more effectively consider several objectives of a project (or projects) simultaneously. Most of In the mid-1960’s, knowledge of water quantity/ the current models include only hydrologic inputs water quality relationships and computer model- and outputs, and the physical operation of a proj- ing capabilities simultaneously reached the point ect or system. Economic, social, institutional, and where it became possible to model many important environmental factors affecting operational man- water quality characteristics in reservoirs and agement are only considered indirectly, or evalu- streams. The first such models dealt with the two ated outside the model. Despite their limitations, best understood quality characteristics—tempera- these models have the capacity to improve both ture and dissolved oxygen. These two characteris- 128 ● Use of Models for Water Resources Management, Planning, and Policy ———— tics were considered to be particularly important have traditionally worked much harder to secure because they are involved in virtually all physical, additional supplies than to control or manage chemical and biological processes occurring in demands. streams. In many instances, domestic water use projec- By the early 1970’s existing models were capable tions have consisted solely of projecting changes in of assisting planning efforts to meet instream needs population and applying established per capita de- based on water quantity requirements, and provid- mand factors to the projected future population. ing information for some policy and regulatory as- In some cases projections have been somewhat pects of instream-needs analysis. However, the more sophisticated. Some analysts recognize that available models could not, in most cases, produce per capita consumption is affected by changes in results commensurate with requirements for opera- demography, technology, and lifestyles, and at- tional management. New models that show prom- tempt to adjust current per capita consumption ise for meeting the requirements for management estimates to reflect anticipated changes in these fac- decisions have recently begun to appear. tors. However, only a modest amount of data is available on which to base such adjustments. The role of models in policy and regulation of instream flow is limited by a lack of knowledge As growth in domestic demands and competing about the qualities of instream flow required to en- uses diminish the relative availability of water, sure the survival of fish, wildlife, and other aquatic water utilities will have to develop and evaluate al- and riparian biota. Many existing instream require- ternatives for obtaining additional supplies, or strat- ments are based on extremely limited information egies for allocating available supplies among com- concerning biological survival and tolerances. Most peting users. Models can be used to establish pric- existing standards establish a single value for in- ing policies, user priorities, and other economic and stream needs, so that in essence a pass-fail condi- technological aspects of system expansion. Models tion exists. In policy and regulatory work, tradeoffs can also play a useful role in examining the likely are critical components of analysis, and tradeoff responses of various sectors (domestic, commercial, analysis is severely hampered when degrees of suc- municipal, and industrial) to strategies that might cess and failure cannot be analyzed. Improved un- be used to achieve targetted reductions in use. derstanding of relationships between instream flow If priority use and pricing systems come into and biotic life would greatly enhance the utility of widespread use, models will be needed to assist in existing models in policy and regulatory areas. determining the conditions under which use priorities should be implemented, and the amounts of Water Use Issues water that should be made available to each user class. Domestic Water Supply When additional supply capacity is deemed nec- Domestic water suppliers in this country usual- essary, models can be used for planning efforts to ly assume a utility responsibility —i.e., that of a develop and expand water distribution systems. regulated monopoly— in their service area. In ef- These models focus primarily on the hydraulics and fect, they agree to provide services to all users within economics of the distribution system itself rather the service area according to an established rate than on water use characteristics. structure, and to assure, insofar as possible, that the service is equally available and dependable for Irrigated Agriculture all users. This does not preclude the possibility of establishing service classes or priorities for various Model use in the area of irrigated agriculture has categories of users (e. g., differentiating between a relatively long history, and has grown more rapid- purely domestic use and industrial use), but such ly and is more widespread than for other water uses. practices are much less common in the water supply Since irrigation occurs primarily where rainfall is industry than in the electric power industry. Be- deficient, farmers have had to be more conscious cause of this ‘ ‘utility’ philosophy, water agencies of the importance of water and of the need to man- Ch. 6—Modeling and Water Resource Issues 129 age a limited supply. Uses of models have ranged these cases, however, the quality of the returned from determining the need for irrigation water and water is substantially altered and the water may not timing applications for specific crops, to develop- be fit for many other uses. ing policies for allocating water among users in Models are currently available to assess the ef- times of water shortage. Models are also used to fects of offstream uses on water quantity and to plan, design, and operate water distribution systems assess such common water quality characteristics for large irrigation projects. as temperature and dissolved oxygen changes. Some of the models available for planning and However, improvements in models are needed for operational management of irrigation water are ex- assessing the economic and environmental implica- tremely sophisticated. They enable users to con- tions of water withdrawals and potential water qual- sider water requirements of individual crops over ity changes due to offstream uses. an entire growing season or for specific intervals Policy and regulatory functions are greatly af- within the growing season. The models can also fected by the lack of adequate modeling capability gage the effect of precipitation on the amount and in this problem area. The volume of some proposed timing of needed irrigation water. Some of the most offstream uses—e. g., coal gasification or liquefac- sophisticated models permit users to consider option and oil shale processing—is so large that deci- tions to defer applying water or to reduce the sions regarding them are likely to affect the econ- amounts of water applied during periods of water omies and ecologies of large regions and involve shortage. These models provide information on the a considerable number of governmental jurisdic- risks of crop failure or the likelihood of reduced crop tions. Information from models would be of great yields, thereby helping farmers to apportion limited value in resolving the controversies and inter- supplies among various crops. Such models also jurisdictional disputes that will inevitably arise. provide information on the economic consequences of buying and selling water entitlements. Efficiency and Conservation The availability of these models to farmers involved in irrigated agriculture will be even more Models for dealing with water use efficiency and important in the future, as competition between ir- conservation are considerably different from models rigation and other nonagricultural water uses in- used in other aspects of water management. With creases in the Western States. the exception of irrigated agriculture, water users in this country have not emphasized efficiency and Other Offstream Uses conservation except during periods of critical water shortages. Consequently, there is no substantial Water is also used for such purposes as cooling body of knowledge regarding efficiency and con- in thermal electric power-generating plants; proc- servation strategies and their economic, social, and ess water and cooling in coal gasification, shale oil environmental consequences. Some data exist on production and other energy extraction and conver- specific conservation practices and their effects in sion processes; hydraulic mining; and for use as a isolated pilot programs under ‘ ‘normal’ conditions, transport medium in slurry pipelines. Many of and some data exist on a wide range of conserva- these uses require withdrawals of large quantities tion practices and effects under emergency condi- of water from rivers and streams. In some cases tions. However, it is doubtful that the existing data (e. g., evaporative cooling, slurry pipelines, and in- base and knowledge (other than for irrigated agri- terbasin transfer) not only are the withdrawals culture) provides a sufficient basis for developing large, but the use is “consumptive’ ‘—i.e., the water the models needed for policy and plannin func- withdrawn is lost from the stream system from g tions. which it was withdrawn. In other cases (e. g., once- through cooling, mineral extraction, and energy Pertinent economic models—e, g., models to de- conversion), while withdrawals are relatively large, termine the effects of water pricing on use—are the use is not consumptive because the water even- discussed in “Social and Economic Models” of this tually returns to the stream after use. In some of chapter. 130 . Use of Models for Water Resources Management, Planning, and Policy

Evaluation of Currently Available model applications; for example, under the issue Surface Water Flow and of ‘flood forecasting and control, the capabilities of models vary for the seven applications addressed. Supply Models Models are rated from A to F, with A indicating that modeling for this purpose does a good job in Table 7 presents evaluations of currently avail- supplying the needed information, and F indicating able surface water flow and supply models. Each that the state of the modeling art for this purpose water resource issue is subdivided into specific is generally unsatisfactory.

Table 7.—Surface Water Flow and Supply Model Evaluation

Overall Issue Information required for applications rating Water avaiiabiiity: 1. Flood forecasting and control a. Flood peaks for channel and bridge design B b. Flood hydrography for reservoir design and operation c c. Simultaneous flood hydrography for flood control system design and operation c d. Flood depth mapping for flood plain land-use planning c e. Effects of land use on downstream flows for upstream land-use planning c f. Flood peaks after dam failures for emergency preparedness planning D g. Soil moisture conditions for land drainage design c 2. Drought and low-flow river a. Low river flows for off stream uses c forecasting b. Timing of drought sequences for estimating cumulative economic impact B c. Soil moisture conditions for precipitation-supplied uses c 3. Streamflow regulation a. Runoff volume for maximum obtainable yield A (including reservoirs) b. Runoff time patterns (within and among years) for reservoir sizing B c. Simultaneous runoff volumes in regional streams for regional water supply planning c 4. Instream flow needs: Fish and Wildlife a. Low river flows for estimating fish support potential c b. Within-year timing of low flows for fish Iifecycle matching B c. Timing of drought sequences for estimating minimum reservoir or lake levels B d. Flow velocities within streams for estimating effects on fish species c Recreation a. Low river flows for sustaining recreation capacity and esthetic appeal c b. Timing of flow sequences for matching with recreation periods B c. Runoff time patterns (within and among years) for estimating the impact of fluctuations in lake levels B Navigation a. Low river flows for determining waterway capacity c b. High river flows for determining navigation interference c c. Formation of surface ice for determining navigation interference D Hydroelectricity a. Timing of flow sequences for estimating run-of-the-river generating capacity B b. Runoff time patterns (within and among years) for designing streamfiow regulations B c. Simultaneous runoff volumes in regional streams for regional generating system planning c Water use: 5. Domestic water supply a. Timing of water use for delive~ system design D b. Water pressures throughout delivery system for delivery system design c c. Volume of use for sizing supply facilities B d. Return flow volumes for designing wastewater collection systems c 6. Irrigated agriculture a. Timing of water use for delivery system design c b. Volume of use for sizing supply facilities B c. Return flow volumes for drainage system design B 7. Other off stream uses a. Volume of industrial use for sizing supply facilities B 8. Water use efficiency a. Effect of increased use-efficiency on return flows for evaluating conservation measures c Rating Key: A Modeling of the physical process at the current state-of-the-art does a good job in supplying the needed information. B Information between adequate and good. C Modeling does an adequate job for most purposes. D Information between unsatisfactory and adequate. F The supplied information is generally unsatisfactory. SOURCE: Office of Technology Assessment. Ch. 6—Modeling and Water Resource Issues ● 131

SURFACE WATER QUALITY

Introduction quality models. Later, the state of the art of water quality modeling is discussed on an issue-by-issue Billions of dollars are spent annually in the basis, analyzing 10 major problems under the gen- United States to protect the quality of surface eral categories of point and nonpoint pollution waters. Unless carefully managed, residual wastes sources. The section entitled ‘‘Evaluation of Cur- from municipalities, industry, and agriculture can rently Available Surface Water Quality Models’ seriously interfere with many beneficial water re- assesses currently available model types. Evalua- source uses. Water quality models are used exten- tions are made both according to the characteristics sively in Federal, State, and local efforts to main- of the models themselves, and for the 10 major tain and improve the quality of the Nation’s sur- problems to which they may be applied. face waters. When considering water quality concerns, four Water quality models serve two general func- basic questions face the analyst: tions. The first is to provide basic scientific insight and understanding about the relationships between 1. What is the quantiy and quality of the water and material inputs and water quality changes. These residuals coming from each point and non- relationships are expressed in the form of mathe- point source? matical equations that interrelate and synthesize ob- 2. How are these materials transported to the servations. The second function is of an engineer- receiving waters? ing nature. Once confidence in these relationships 3. How are these wastes transported within the is obtained, the equations can be used to help receiving water? manage, plan, and make policy. Given the present 4. What processes transform waste residuals with- state of scientific knowledge and engineering in a water body? development, existing models can generally pro- Given the response of the system, the analyst vide a limited basis for water quality decision- must further consider the following quest ions: making. ● What deleterious effects do these wastes have Mathematical models of water quality are most on beneficial uses? frequently used for planning, to some extent for ● Do existing standards reflect the magnitude policymaking, and to a lesser degree for day-to-day of the effects? operations and management. Their most common ● What control alternatives are available, how use is to determine the degree of treatment required well do they perform, and how much do they for a specific wastewater discharge in order to cost? achieve or maintain a desired receiving water quali - ● Are these control alternatives politically, eco- ty. Other uses include determining the magnitude nomically, and esthetically feasible? and effects of urban runoff, and assessing the effectiveness of alternative measures for preventing All of the above information is needed for man- soil erosion and the resulting sedimentation within agement, planning, and policy decisions. Models water bodies. are available, in varying degrees of detail and accuracy, to help the analyst address each of these Because models simply quantify existing scientif- questions. ic knowledge about water quality, a basic understanding of the processes that underlie model equa- The common basis for the majority of water qual- tions and assumptions is helpful in assessing model ity models is the principle of ‘‘mass balance. capabilities. The next section, ‘ ‘Types of Models Water and any material inputs from natural or hu- Used in Surface Water Quality Analysis, describes man sources are followed: 1 ) from their point of the current state of scientific knowledge about deter- origin; 2) as they travel to the water body; and minants of water quality, and examines how well 3) as they travel within the water body. The models this knowledge is incorporated into present water account for biological, physical, and biochemical 132 . Use of Models for Water Resources Management, Planning, and Policy

reactions that occur, and additions of water or ma- dynamic regime of the water body and its water- terials. shed; and the last, the biological, chemical, and physical processes that affect water quality. To run these models, users must provide quantitative estimates of the characteristics of the watershed and the receiving water body. Source quanti- Source of Materials ties, constituents, and other pertinent characteristics Water bodies may receive point source discharges must be enumerated, and the numerical coefficients from municipal, industrial, and agricultural activ- that describe the above reactions must be known. ities; dispersed or nonpoint source runoff from these Water quality models have one aspect that is both same areas; natural inputs from undisturbed water- a vice and a virtue—most provide an absolute nu- sheds; and additional chemicals from rainfall. merical value for any given variable such as the con- The chemical characteristics of effluents from centration of a pollutant. While it is desirable to municipal sources are well known with respect to have such a number, often no indication of the both average values and their variations. This is possible error is given. In practice, most water also true for many industries that generally pro- quality projections are subject to large errors and must be validated with field observations. duce one or a few products, such as the pulp and paper, canning, and steel industries. However, in- However, water quality models are still very use- dustries that produce a variety of products, such ful in planning contexts, for example, because rel- as organics, synthetic chemicals, and pharmaceuti- ative effects of control alternatives can be analyzed cals, produce discharges that are more difficult to with sufficient confidence for many purposes. Mod- characterize. el projections, when combined with the professional Information on agricultural and feedlot sources judgment of water resource analysts, are often the of waste is meager, but has been improving in re- best information available to aid the decisionmaker cent years. Irrigation return waters pose difficult in evaluating alternatives. problems, particularly in the mid- and far-western regions of the country where high background concentrations of salts of natural origin prevail. The Types of Models Used in Surface time-variable nature of return flows, which are both Water Quality Analysis point and distributed, introduces additional complexities. Our social and scientific awareness of All water bodies are affected by inputs from nat- these problems is relatively recent; consequently, ural sources and human activities. The accuracy with which models can estimate relationships be- the historical data on these sources are minimal, tween these inputs and the water quality response and many gaps remain in current knowledge of the determines their utility for management, planning, governing phenomena. and policy purposes. Thus, current levels of scien- The ability to quantify pollutant loadings from tific and engineering knowledge about these rela- a variety of sources is critical, particularly with tionships form the basis for assessing surface water respect to differentiating between point sources, quality models. which are readily controllable, and nonpoint sources, which are relatively difficult to identify and Water quality models can be divided into three components that describe: control. Assigning realistic values to distributed nonpoint sources is very difficult, given the pres- ● source of materials; ent state of knowledge and data, Current models ● transport to and within the receiving water; provide at least some assessment of the problem. and The most significant information gap lies in ● processes occurring within the receiving water; quantifying toxic substances from nonpoint sources The first component estimates the inputs of sub- or from residues of toxic materials created by past stances through human activities and natural phe- activities, e.g., from riverbeds and from landfills nomena; the second, the hydrologic and hydro- that leach into water systems. Ch. 6—Modeling and Water Resource Issues ● 133

Transport to and Within Receiving Waters than those of lakes. In addition, more extensive water quality data exist for rivers and streams, par- Point discharges are transported by pipes, open ticularly for such constituents as dissolved oxygen channels, or other conveyance devices from the and coliforms (bacteria used to indicate the pres- point of origin to the receiving water on a regular ence of sewage). basis. Nonpoint discharges move through storm drainage systems, via overland flow, and through Eutrophication (excess algae or aquatic weed subsurface flow to the receiving water as a result growth) is another widespread problem. The nutri- of rain events. Consequently, the quantities of ents that cause eutrophication originate from a vari- materials entering water bodies from nonpoint ety of municipal, industrial, agricultural, and natu- sources are much more difficult to predict. ral sources. While the state of the art permits some model-based assessment, data requirements are so Most surface water quality models include a sur- extensive that these techniques are often imprac- face water flow submodel as part of the program, tical. Simplified approaches, involving the nutrients since in most cases it is necessary to predict runoff phosphorus and nitrogen, presently yield results and flow quantities before making quality estimates. that may be indicative and, in certain cases, ade- Many of the models discussed in the previous sec- quate for the intended purpose. tion on surface water flow are used as components of surface water quality models. For inorganic and organic chemical water quality, the present state of knowledge is mixed. The Pollutant transport by rivers and streams is, in biochemical reactions of certain industrial chemicals general, better understood than transport within are sufficiently understood to permit the develop- lakes. Transport in streams depends primarily on ment of reliable models. This is true for a wide flowing water; within lakes, and some complex river range of chemical compounds of relatively simple systems, movement of pollutants occurs by diffu- structure, which are commonly present in industrial sion and dispersion as well—difficult processes to effluents and which are susceptible to the present- model. In addition, a longer and more extensive ly available treatment processes. While the reac- data base is available for streams than for lakes. tions involving metals are not as well understood Transport in streams can be approximated by as those of the simple industrial chemicals, they simple one-dimensional models—the one dimen- have been developed to a degree that will permit sion being the direction of flow. Under certain con- at least a marginal analysis and projection. ditions, simple models can adequately simulate On the other hand, for more complex com- transport in lakes, but often more complex two- and pounds, many of synthetic composition, far less is three-dimensional models are necessary. The state known about reactions, byproducts, and removal of knowledge and computational techniques are by present treatment techniques. These substances, such that only the most proficient analysts can use which inciude many toxic materials, may be mod- these models. eled with simplifying assumptions, yielding reason- The above remarks apply to situations that are able projections in limited cases. However, on the not highly time dependent. When water quality whole, current methods of analysis are regarded as analysis must incorporate such factors as storm only marginally reliable, A similar assessment ap- surges from combined sewers or rapidly changing plies to complex metals when concentrations ap- river flows, the models must be considerably more proach or exceed toxic limits. Water quality models complex. These models are still in the developmen- that analyze these substances are presently being tal stage and their results are only marginally useful developed. at present. A second area of notable uncertainty is the accumulation of toxicants in the food chain leading to Processes Occurring Within fish. Much research has been undertaken over the the Receiving Water past decade to advance basic understanding of the In general, the chemical, physical, and biological problem, collect data, and develop models, some processes of rivers and streams are better modeled of which appear to be very promising. Preliminary 134 ● Use of Models for Water Resources Management, Planning, and Policy —— .—

Photo credits: @ Ted Spiegei, 1982

Researchers are exploring natural capabilities to reduce nutrient levels in effluent flows as a potential means of tertiary sewage treatment. At left, water in a meandering stream is cleansed through contact with vegetation and reaerated on its way to the Hudson River; at right, a Florida cypress dome is fertilized with the nutrients in partially treated effluents from a 150-unit mobile home park. Models are available to estimate the effectiveness of various treatment methods in removing such nutrients as phosphorus and nitrogen, and to assess the effects of nutrients on biological processes in lakes and streams food chain and fisheries models are available; how- Nonpoint Source Issues ever, these are in a relatively primitive state. Al- though they may provide some insight and under- Urban Runoff standing, they are neither sufficiently calibrated nor Urban runoff (along with agricultural runoff) is adequately validated for management purposes. one of the most difficult waste discharges to con- The same may be said for aquatic ecosystem trol because of its intermittent nature and varying models that describe changes to aquatic plant and quality. Federally mandated control and manage- animal populations subjected to water quality ment of urban runoff has created the potential for stresses. Ecosystem theory-the basis for such mod- increased use of urban runoff models. els—is still in a developmental stage. However, the At present, urban runoff models are most helpful results of laboratory studies on the effects of specific in planning, primarily for water quality manage- pollutants on sensitive organisms have been incor- ment and comprehensive areawide planning. The porated into water quality models with some suc- best examples lie in the section 208 programs of cess. the Clean Water Act—particularly the Nationwide —

Ch. 6—Mode/ing and Water Resource Issues 135

Urban Runoff Program. Such planning is designed of point source and nonpoint source wastes in a to provide each State and the Environmental Pro- specific area, the effects of these wastes on the tection Agency (EPA) with information on point receiving water, and the effectiveness of nonpoint source and nonpoint (including urban runoff) treat- source control in alleviating the problem. ment needs and the effectiveness of treatment methods. Urban runoff models such as EPA’s Storm- Urban runoff models do not appear to have at- water Management Model and the Corps of En- tained the credibility necessary to be used as regu- gineers’ STORM can simulate the quantity and latory tools at this time. These models require an quality of runoff from a specified runoff area and extensive local data base, and such information is can be used to compare the effectiveness of alter- usually unavailable, except for cities in which spe- native control strategies. These models may also cific studies have been performed to develop, cali- be linked to receiving water models to gage the ef- brate, and test such models. fects of urban runoff on receiving water quality. Erosion and Sedimentation Urban runoff models can also play an important role in Federal and State agency policy decisions. Models of erosion and sedimentation are devel- Federal agency construction grants allocations, and oped primarily by such Federal agencies as the requests for such funds by State agencies, could be Corps of Engineers, the Soil Conservation Service, based in part on estimates of the volume and quality the U.S. Geological Survey, and, to a lesser extent,

Photo credit: U.S. Department of Agriculture Two years of low rainfall on the Big Canyon Ranch near Sanderson, Tex., greatly reduced plant cover levels, setting the stage for extremely high runoff rates on the draw pictured above after rainstorms hit an area 30 miles away. Plant cover is a major determinant of soils’ abilities to absorb moisture and resist erosion; runoff and erosion models consider cover levels as one of many factors in estimating flows and sediment transport 136 ● Use of Models for Water Resources Management, P/arming, and Policy

EPA. Extensive use is made of erosion and sedi- balance in agricultural soils, farmers may apply mentation models by Federal, State, and local agen- more water to their crops than is required for plant cies concerned with river management. Construc- production. The additional water leaches out ex- tion agencies use these models to assist in opera- cess soil salts that may either flow overland to sur- tional management, e.g., in dredging navigation face waters or percolate to the ground water. The channels and operating reservoirs. Sedimentation erosion of soils with high salt contents, such as the is a critical factor in reservoir management, as it marine shales found extensively in the West, and can reduce a reservoir’s useful volume. River the input of salts from natural sources, such as authorities must have information on rates of brines, also contribute to excess salinity. Finally, sedimentation and ways of alleviating or mini- the concentration of salt in surface waters can in- mizing sedimentation to operate their reservoirs crease due to evaporation, reductions or diversions most efficiently. in flow, and plant transpiration. Local, State, and Federal agencies concerned Salinity, as a physical process, is one of the best with forestlands, rangelands, and farmland man- understood pollution problems, and relatively easy agement continually seek better ways to minimize to model, Many models exist to predict salt concen- soil erosion. They employ models to guide the selec- trations in agricultural drainage as a function of tion of effective management techniques. crop, soil type, and irrigation practice; downstream salinity concentrations; and the effects of excess A primary concern is the large amounts of nu- salinity on crops, metal deterioration, soap con- trients (especially nitrogen and phosphorus) consumption, and health. A well-developed data base tained in eroded soils. Soils reaching waterways complements these models. may impart those nutrients to the water, potentially causing nuisance algal growths or other symptoms Models are widely used to develop management of eutrophication. strategies for salinity control. They can provide managers with information on the effectiveness of Probably the greatest utility of erosion and sedi- control options for reducing downstream salt con- mentation models lies in the area of planning. For centrations. In addition, these models are useful example, the Corps of Engineers employs such for evaluating the likely effects of proposed regula- models to plan and design erosion control structions. From a planning standpoint, these same tures along rivers and coastal areas and to estimate models are used to develop areawide salinity con- the extent of sediment accumulation over the life trol plans and can aid in setting funding priorities of a reservoir. The Soil Conservation Service uses to implement these plans. erosion models to plan erosion control programs on farmlands and forestlands. In the ares of policy, salinity is an important aspect of international water rights issues and treaty Because toxic chemicals often adhere to river obligations between the United States and Mex- sediments, sediment transport models are used to ico. In particular, the salinity of the Colorado River predict the movement and fate of toxicants accident- has been a major international issue for some years. ally released into waterways. EPA relies on water The increase in salinity of the Colorado from saline quality models incorporating sediment transport return flows before it leaves the United States is submodels to follow the transport of Kepone down a major problem for water users in Mexico. Models the James River to the Chesapeake Bay. The agen- have been used to determine whether planned con- cy is using this information to plan monitoring pro- sumptive uses from the Colorado Basin will allow grams and subsequent mitigation programs, if the United States to meet its treaty obligations for needed. delivering water at or below a specified salinity.

Salinity Agricultural Pollutants Several factors may cause the buildup of excess Agricultural pollutants are found in runoff from salinity in surface waters. One major source is irri- irrigated and nonirrigated agricultural lands and gation return flows. To maintain a favorable salt pastures. The pollutants include soil particles Ch. 6—Modeling and Water Resource Issues ● 137 eroded from the land; organic substances from decaying vegetation, animals, and feedlot waste; i nitrogen and phosphorus from commercially produced fertilizers as well as from animal waste; and pesticides that have been applied but are not yet degraded. These pollutants find their way into near- by receiving streams, where their effects must be assessed. Agricultural pollutants are generally considered to originate from nonpoint sources; animal feed lots, however, are considered point sources. Like other point sources, the latter must be treated to meet effluent and receiving water standards according to sections 301 and 303 of the Clean Water Act. Nonpoint sources are eventually to be controlled as well, but standards and guidelines for implementing controls have not yet been promulgated. Mathematical models aid in assessing the instream effects of these point and nonpoint sources —such analyses play an important role in regulating pollution sources. The models for tracking organic materials and their effects on oxygen resources in streams are well developed, well documented, and easily usable by personnel with appropriate analytical skills and knowledge of water quality management principles. Such models should also withstand the scrutiny of litigation. Models for nutrients and pesticides, however, are not used as broadly as Photo credit: @ Ted Spiegel, 1932 models that predict levels of dissolved oxygen. Agriculture can also serve as a means of treating certain Mathematical modeling of agricultural pollutants water pollutants. Lubbock, Tex., utilizes a 3,000-acre farm as its tertiary disposal facility, employing nutrient-laden finds extensive use in planning. Models have been waters to irrigate and fertilize crops used primarily for section 208 studies of areawide pollutant problems and water treatment needs. Airborne Pollutants Such studies enable States and EPA to establish Since the enactment of the 1971 Clean Air Act, priorities for treatment, based on estimates of the mathematical models have been used as regulator effects of point and nonpoint sources on receiving y tools by Federal and State agencies that are assigned waters. responsibility for air pollution enforcement. Such

Not only do Federal and State agencies use math- models determine the relationship between dis- ematical models for the kind of planning mentioned charge and downwind exposure concentrations of above, but they also use these models to determine common air pollutants such as sulfur oxides, nitro- the effectiveness of treating agricultural pollutants, gen oxides, and particulate. Some of these pollut- recommend funding levels to Congress, and pro- ants are transferred from the air medium to water pose legislation for controlling agricultural and thus contribute to water pollution. Such materi- pollutants. In these cases, mathematical models ah include windblown dust, hazardous substances, may be the only means of linking the pollution and compounds that may eventually produce acid source to effects on the receiving waters—a con- precipitation. nection that is important in estimating the benefits The transfer of pollutants from air to water has of regulatory programs. received increasing attention in the last few years. 138 . Use of Models for Water Resources Management, Planning, and Policy

Hazardous substances in incinerator effluents and stand judicial scrutiny. Waste allocation is par- windblown erosion from landfill sites are problems ticularly complex, however, when a number of for which mathematical models may be used to an- discharges reach a common receiving water near ticipate and formulate control strategies. Models the same point. In such cases, the allowable of short-range pollution transport (less than 200 wasteload can again be determined by a mathemat- km) are currently available. The potential conse- ical model, but assigning wasteloads equitably quences of acid precipitation, and of the deposi- among the contributors must be a legal and admin- tion of heavy metals, radioactivity and other haz- istrative decision. ardous materials from powerplant air emissions, Water quality models have been used extensively may require Federal and State agencies to assess in planning for treatment needs throughout the Na- future water quality problems resulting from in- tion. As part of section 208 of the Clean Water Act, creased energy production. Models of long-distance point and nonpoint wasteloads were to be deter- pollution transport, and of atmospheric processes mined for segments of the Nation’s waterways. that may produce acid rain, are in early stages of Mathematical models were used in these cases, first development. to estimate current loadings from the point and nonpoint sources, and then to estimate the impact Point Source and General Issues of these loadings on the receiving stream. Based on the magnitude of these effects, the need for Wasteload Allocation (Point Source) wasteload reduction was determined. Then, based Wasteload allocation refers to the process of on the ratio of point source to nonpoint source dis- determining the amount of some waste material that charges, Federal and State agencies could estimate a particular discharger is allowed to release by ana- where the greatest water quality improvement could lyzing the relationship between discharged amounts be achieved at the least cost. and resulting concentrations in the receiving water. Probably the most dramatic and exemplary pol- This cause-effect relationship may be determined icy-level application of these water resource models after the fact through sampling programs, or before was undertaken by the National Commission on discharges occur with the help of mathematical Water Quality. The commission, mandated by models. Congress as part of the 1972 Federal Water Pollu- Water quality models find their most appropriate tion Control Act Amendments (Public Law 92- regulatory roles in estimating waste treatment needs 500), undertook a number of assessments of the for compliance with the Clean Water Act. The act social, economic, technical, and environmental im- sets forth two criteria for water quality standards: pacts of implementing the other sections of the act. 1) effluent requirements for regulating ‘ ‘end-of- Among the commission’s responsibilities were a set pipe” discharges, as specified in section 301 of the of water quality studies to evaluate the act’s im- act; and 2) receiving water standards, as specified pact on some 40 specific areas around the United in section 303 of the act. Discharges who meet ef- States. Water quality models were used extensive- fluent standards may be required to provide fur- ly in these studies and were, in fact, necessary to ther treatment if resulting waste discharges cause carry them out. Study results indicated that the ef- higher-than-acceptable receiving water concentra- fluent regulations of the 1972 act should be altered tions. Wasteload allocation models determine the to reflect more realistically attainable levels of treat- maximum allowable level of discharge for individ- ment in the allotted time periods. The work of the ual producers in order for pollutant concentration commission contributed to policy changes within levels in receiving waters to be at or below existing EPA, and influenced congressional formulation and standards. Removal techniques to meet these limits passage of the 1977 Clean Water Act (Public Law can then be selected. 95-21 7), which incorporated many of the commission’s recommendations. Mathematical models for this procedure are well developed and documented, can be adapted to re- Wasteload allocation models were critical to the ceiving waters of different types, can be easily used commission’s ability to demonstrate the conse- by regulatory staff, and are reliable enough to with- quences for the Nation’s receiving water quality of Ch. 6—Modeling and Water Resource Issues ● 139

Photo credit: EPA-DOCUMERICA, Doug Wilson

Untreated water from a pulpmill in Puget Sound, Wash. implementing the 1972 act. The study also revealed Mathematical models for thermal wastes range some shortcomings in then-current modeling capa- from fairly simple one-dimensional models to more bilities, however. Contractors performing work for complex two- and three-dimensional models. Most the commission relied primarily on dissolved solids of these models have been developed through the and dissolved oxygen models; models for nutrients support of EPA and the electric utility industry and and toxic materials were applied in only a few situa- have been applied in many locations. Most regulations, largely because existing data bases were in- tory staffs can operate the simpler thermal waste adequate for calibrating and validating them. models, but the more complex multidimensional models require well-trained staff. Thermal Pollution The electric utility industry uses mathematical Thermal effluents are among those regulated by models extensively in applying for construction and the Clean Water Act. Effluent limits have been set operation permits for nuclear powerplants through for thermal wastes as well as for allowable temper- the Nuclear Regulatory Commission, and in pre- ature increases in receiving waters. Zones of influ- paring environmental impact statements as re- ence and resulting temperature increases from ther- quired by the National Environmental Poiicy Act mal effluents can either be monitored directly or of 1969. Under the latter act, the permittee must predicted with mathematical models. show the extent of the environmental impact of its 140 ● Use of Models for Water Resources Management, Planning, and Policy facility, in particular the impact of the thermal long-term toxic material control should find wide- waste. Such effects are routinely forecasted by using spread application. mathematical models. Drinking Water Supply Toxic Materials The Safe Drinking Water Act is the principal Compounds that cause some injury to humans Federal legislation regulating the quality of drink- or other organisms of concern are classified as toxic ing water. It, along with State statutes and local materials. Such materials are not necessarily lethal, ordinances, regulates the quality of public drink- but may be compounds that produce such sublethal ing water. Regulations apply to water quality at effects as cancer, birth defects, or reproductive the end of the treatment process; consequently, failure. streamwater quality models have no roles per se Toxic materials are regulated under several stat- in regulating drinking water under this act. How- utes, including the Clean Water Act, the Toxic ever, toxicology models, which relate concentrations Substances Control Act of 1976 (Public Law of various hazardous substances to human health 94-469), the Resource Conservation and Recovery risks, are used to aid in setting standards. These Act of 1976 (Public Law 94-580), and the Safe models use differing methods for extrapolating data Drinking Water Act of 1974 (Public Law 93-523). from animals to humans, so that resulting estimates Regulation under this last act is discussed in the of human risk may diverge widely. The OTA re- section entitled “Ground Water Quantity and port, Technologies for Determining Cancer Risks From Quality. ” Although control is focused on technol- the Environment, provides an assessment of toxicology ogy-based standards, mathematical models have models. potential roles in enforcing portions of these acts. As with other pollutants, effluent requirements have The quality of the raw water is an important fac- been established for point sources based primarily tor in supplying high-quality water for human con- on removal techniques. However, receiving water sumption. Where raw waters are degraded by up- criteria must be met as well. Modeling for toxic stream users, water quality models can be used to material concentrations may be required at some predict water quality at the point of intake to deter- future time to determine further treatment needs mine the level of treatment needed. In particular, if receiving water standards are not being met. water quality models are used in determining when intakes should be closed due to contaminants origi- While legislation exists for control of nonpoint nating upstream. For example, a spill of carbon tet- source toxicants, implementation has been given rachloride in the Ohio River several years ago low priority. As controls are applied, however, forced water users downstream to close intake struc- ground and surface water quality models could play tures at appropriate times to avoid contaminating an important role in determining the cost effec- the water supply. Models were used to predict when tiveness of alternative control measures, Mathemat- and how long the carbon tetrachloride would be in ical models can also be used to design monitoring the vicinity of the intake structures. networks so that stations can be best located and sampled to gain maximum information from moni- tormg. Water Quality Impacts on Aquatic Life As with other issues, mathematical models for Models for predicting water quality impacts on toxic materials have greatest utility in the planning aquatic life involve two steps: 1 ) estimating concen- process. Models can be used to anticipate problems, trations of those materials that may affect aquatic and to test different management approaches for life (positively or negatively), and 2) comparing removal effectiveness and managerial efficiency. calculated concentrations with accepted criteria to Since regulations for controlling liquid and gaseous judge the consequences of those concentrations to sources of toxic substances are currently being im- the ecosystem. This latter step is seldom incor- plemented, and those for hazardous solid wastes porated into the model structure, and requires pro- have recently been issued, models for planning fessional judgment by aquatic ecologists. Ch. 6—Modeling and Water Resource Issues ● 141

The models used to assess impacts can vary from uneven level of current modeling capability for sur- very simple models for calculating the effects of con- face water quality analysis. centrations of selected materials, to very complex models incorporating several different types of Type Z is a standardized procedure or technique pollutants and their effects on numerous organisms. that may be routinely performed without a com- The complex models are the least reliable, due to puter. It involves simple mathematical equations, the lack of data to support many of the necessary statistical techniques, and graphical procedures. Ex- assumptions and the great difficulty in calibrating amples include use of the Streeter-Phelps stream and validating them. Both types of models require model for evaluating dissolved oxygen down- considerable professional judgment in applying the stream of point sources (although this is often pro- results to field situations. gramed into complex models), and evaluating lake eutrophication potential with diagrams or regres- Models to determine water quality impacts on sion equations. While the procedure does not in- aquatic life are primarily of value in the planning volve a computer, it is not necessarily unsophisti- process. This is due to the kinds of applications that cated. On the contrary, some ‘‘desktop’ proce- can be made of these models, the current state of dures are mathematically quite sophisticated, their development, and the number of areas for whereas some complex digital computer models are which data are adequate to apply them. nothing more than a programed version of intui- Aquatic life impact models can be usefully ap- tion. Finally, a Type I model may still require con- plied if a theoretical analysis of the aquatic system siderable time and effort and the use of computa- is coupled with coefficients derived from controlled tional aids (e. g., hand calculators) to be fully oper- laboratory experiments. Examples include models ational. of the movement and effects of Kepone in the James Type II is a computerized version of a Type I River, of polychlorinated biphenyl (PCBS) in the model. This may avoid the tedium of routine calcu- Hudson River, and of PCBS in the Great Lakes. lations and greatly expand the amount of data that Both the Kepone and PCB models facilitate impact can be processed. The level of complexity of the assessment by allowing researchers to compare ex- analytical technique, however, is still low. posure concentrations to tolerable levels, while the P(2B models can predict alterations in populations Type III is a procedure that is sufficiently com- if toxic interactions are included. These models plex that a computer is required for its use. Such have been used to forecast the effectiveness of alter- models generate numerical solutions for sets of native remedial actions, and thus help provide a mathematical equations that could not be solved basis for future regulatory activities. prior to the advent of modern computers. Many individuals, consultants, universities, industries, Evaluation of Currently Available and public agencies have constructed such models. Surface Water Quality Models Type IV is the same as a Type III model except A model’s level of complexity and its degree of that it is termed operational, meaning: 1) documen- availability provide the basis for a simple scheme tation (e. g., user’s manual, description, and theory) of classification. Accordingly, four generic types of is available; 2) the program has been well tested models are outlined below, and their basic capabil- and its credibility established by groups other than ities are summarized. In the evaluation table (table the model developer; 3) the program is available 8), these four generic model types are rated accord- and accessible to interested users (this does not pre- ing to their utility in analyzing five major aspects clude proprietary models); and 4) user support is of each of the 10 issue areas discussed above. The available either from the model developer or from evaluation table also assigns an overall rating for other groups. Although several hundred large water modeling sophistication in each issue area. Using quality models are described in the literature, less a potential scale of zero to 10, actual assigned than 100 can be termed operational. A Type IV ratings range between 1 and 9, indicating the model can thus be used by others with relative ease. 142 ● Use of Models for Water Resources Management, Planning, and Policy

Table 8.—Surface Water Quality Modei Evacuation

Generic type Iv I II Ill Computer, Overall level No computer, Computer, Computer, complex, of modeling Issue not complex not complex comDlex operational sophistication Nonpolnt source pollution and land use Urban runoff: Source/generation...... c c B Transport to receiving water...... — A A Transport in receiving water...... c B Impacts on beneficial use...... ; c c Control options/costs...... B B B Erosion and sedimentation: 4 Sourcelgeneratlon...... c c c Transport to receiving water...... : — c — Transport in receiving water...... B — c — Impacts on beneficial use...... B — — — Control options/costs...... A — — — Salinity: 9 Source/generation...... A A A — Transport to receiving water...... A A A — Transport in receiving water...... A A A A Impacts on beneficial use...... B c c — Control options/costs...... A — — — Other agricultural runoff: 3 Source/generation...... c c B B Transport to receiving water...... — B A A Transport in receiving water...... — c B Impacts on beneficial use...... c c c : Control options/costs...... B B B B Airborne pollutants: 6 Source/generation...... A A A A Transport to receiving water...... A A B B Transport in receiving water...... c c c — Impacts on beneficial use...... c c c — Controi options/costs...... A A A A Water quality (other than nonpoint sources and land use) Wasteioad allocation: 7 Source/generation...... A A A Transport to receiving water...... A A A Transport in receiving water...... A A A Impacts on beneficial use...... c c c Controi options/costs...... B B B Thermai poiiution: 9 Source/generation...... A A A Transport to receiving water...... A A A Transport in receiving water...... A A impacts on beneficial use...... : c c Controi options/costs...... A A A Toxic materiais: 1 Source/generation...... c c c c Transport to receiving water...... — — c c Transport in receiving water...... — c c Impacts on beneficial use...... z — c — Controi options/costs...... c — c — Drinking water quaiity: 2 Source...... A — c — Treatment...... — c — Impacts on beneficial use...... ; — — — Water quality impacts on aquatic iife...... B — B B 3 Key: A Reliable, credibie modeling may bereadily used for most problems ofthis subissue. Some models maybe suitable forreguiation and design, B Same as C, but some models may beuseful for planning andrelated purposes, and suitabie for determining relative effects. C Modeling lspossible. Credibility andreliability of results is Iowdueto weaknesses in the database. — Modeling of this type is not usually performed. Overall level of modellng sophistication: O No models available. 10 Routine use of models of all types, Ch. 6—Modeling and Water Resource Issues ● 143

It is not possible to state categorically that one currently judged most successful for the issues of type of model is to be preferred over another—in salinity, wasteload allocation and thermal pollution. particular that a Type IV model is to be preferred The weakest issue is toxics, due mainly to the lack over a Type 1. The appropriateness of an analytical of data necessary to determine the changes these tool depends on the particular problem and objec- substances undergo in receiving waters. tives of the analysis. In the most general terms, Successful modeling for a given issue requires Type III and IV models have greater potential for a good deal more than the application of sufficient accuracy and credibility than do Type I and II mod- modeling expertise. To model the governing prin- els. But there are many instances in which data and ciples of physical processes, the principles them- theoretical formulations are so lacking that the use selves must be well understood. Scientific under- of a complex computerized model is simply not war- standing of biochemical phenomena related to water ranted, even if one already exists. For example, the quality is not sufficiently advanced to permit highly fate of toxics in the environment is of immediate accurate modeling; the governing principles of tem- concern to the public, but the various parameters perature, on the other hand, are relatively well doc- and coefficients that describe the sources, sinks, and umented. Data constraints place a further limita- transformations of these chemicals are so ill-defined tion on the utility of models—processes that are that the sophistication of toxic model formulations thoroughly understood can be accurately modeled far outstrips the present data base. Simpler proce- only if data are available to predict conditions for dures are often much more credible. the location under study. This evaluation accounts The evaluation table presents a summary of infor these factors in assessing model utility, rather formed opinion regarding the utility of models in than simply assessing the state of the modeling art analyzing specific issue areas. Overall, models are in itself.

GROUND WATER QUANTITY AND QUALITY

to long-range Planning for maximizing the utility Introduction u. of an entire aquifer. Models can be designed, for Ground water systems, unlike surface water sys- example, to calculate how pumping from a new well tems, are completely concealed from view; conse- might affect local ground water levels, or to predict quently, conceptual, physical, or mathematical how far contaminants might move in a given period models are the only way to achieve an understand- of time. However, models can also be designed to ing of their potential yields and responses to natural answer more complex questions about potential or man-related stresses. Simple ground water prob- quantities of recoverable water in regional ground lems may be analyzed using physical hydraulic con- water systems as more and more wells are drilled cepts and assumptions, perhaps expressed in sim- and pumped. These evaluations can provide infor- ple paper calculations. However, more complex ap- mation for regulatory decisions regarding allowable plications require the use of large amounts of data, limits on total ground water use, optima] pump- gathered from multiple test wells at many different ing rates and placement of new wells, or control- times. The only way to integrate this information ling subsurface waste injection that may contami- involves using computers that are capable of solv- nate ground water. ing hundreds or even thousands of complex mathematical expressions simultaneously. The principal types of situations for which models are used include: Public agencies that issue water use permits or otherwise manage regional ground water resources . changes in ground water availability; - ● must rely on models to forecast effects of ground changes in ground water levels due to pump water use. Applications range from day-to-day ing from wells, land drainage, or injecting management of a community’s ground water use water into an aquifer; 144 ● Use of Models for Water Resources Management, Planning, and Policy

● changes in ground water flow caused by altera- fractured media, water cannot move through the rock tions in surface water flow patterns; as in porous flow, but moves through cracks or cav- ● movement of contaminants through ground ities in the rock. In general, better estimates of flow water systems from waste disposal or encroach- can be made with models for porous media than ment of saltwater; and for fractured media. ● settlement or subsidence of the land surface due to withdrawals of ground water. Saturated flow models consider the flow of water only. These models assume that water completely The greatest limitations on the effective use of fills the open spaces between soil grains or rock. ground water models are not computer size or accu- Data used in these models include: 1) inherent racy, but: 1) the basic understanding of physical characteristics of the system, such as the transmis- and chemical processes in ground water systems; sivity (ability to transmit fluids) and storage (ability 2) the cost of collecting sufficient field data to to store fluids) characteristics of the rock or soil; describe the characteristics of the ground water sys- and 2) changes imposed on the ground water system; and 3) the availability of well-trained person- tem, such as water entering or leaving the system. nel. In general, ground water quality models are Results from the model consist of calculated fluid much less reliable than ground water flow models. pressures or water levels at time intervals for specific While models are widely used to address ground locations in the ground water system. Saturated water availability questions, many ground water flow models are used for almost all types of ground quality models have not yet been proven reliable water quantity applications. enough for routine regulatory application. Above the water table, the open spaces between Types of Models Used in Ground soil grains or in rock voids contain air as well as Water Resource Analysis water. A model that considers a mixture of air and water simultaneously is called an unsaturated~ow Ground water models are usually classified ac- model. Data requirements for unsaturated flow mod- cording to the physical and chemical processes they els include all of those needed for saturated flow describe. The two major types are: 1) ground water models plus data describing the reduction in trans- flow models; and 2) contaminant transport models. missivity (resistance to water flow) due to the pres- Generally, ground water quantity and yield prob- ence of air. Besides fluid pressures, the models also lems are analyzed with flow models, while ground calculates variations in the amount of air contained water quality issues require the use of contaminant in the pore spaces. Unsaturated flow models are transport models. The two major model types are useful for small-scale problems such as crop irri- examined below, and ground water quantity and gation or water flow adjacent to landfills. quality issues are analyzed in “Ground Water Quality Issues. ” Lastly, the section evaluates the Multifluid models deal with the simultaneous flow utility of currently available ground water models. of immiscible fluids in the soil or rock—e. g., a gasoline-water or oil-water model. These models are Ground Water Flow Models similar to unsaturated flow models, except that gasoline rather than air is the second component of Flow models determine rates and patterns of fluid the fluid mixture. Multifluid models can help to movement through soil or rock. Both the type of assess the consequences of fuel tank leaks or oil spills fluid and the nature of the soil or rock are used to on land. further characterize the flow model. Types of fluids modeled include water only, water and air, or water Contaminant Transport Models and an immiscible fluid (a fluid that does not mix with water, such as gasoline). The soil or rock types Contaminant transport models analyze the may be either porous or fractured material. Flow movement, mixing, and chemical reactions of con- in porous media is primarily through interconnected taminated water in the native water and the soil voids (open spaces) between individual grains. An or rock through which it flows. Like flow models, example of this type of material is sandstone. In transport models are also classified by fluid and w media types, as well as by the chemical reactions Nonconservative transport models can simulate considered. a variety of possible chemical reactions. For example, models may consider the fate of water-borne Three major processes control the movement and pollutants that become fixed or adhere to the soil changes in concentrations of pollution in ground or rock surface, thereby coming out of solution and water: 1) movement due to ground water flow not moving with the water. However, while these (called advection or convection); 2) the mixing of and more complex reactions can be addressed in ground waters having different levels of contamina- theory, in practice, chemical reactions are normally tion (called hydrodynamic dispersion); and either ignored or are approximated by simple equa- 3) chemical reactions. Contaminant transport tions. Simple equations are used because the precise models are normally classified according to whether mechanisms for the chemical reaction are general- they consider chemical reaction. Two major types ly unknown or are too complicated to be used in of models are generally recognized: 1 ) conservative field applications. transport models, which do not consider chemical reactions; and 2) nonconservative transport models, Data required for both conservative and noncon- which do. servative transport models include the hydrologic 146 ● Use of Models for Water Resources Management, Planning, and Policy ..—— data discussed previously for flow models, as well Computer models can be very useful tools for es- as data describing mixing and chemical reactions. timating an aquifer’s response to alternative devel- Models generally calculate projected concentrations opment plans. Assuming that the geometry and of the various pollutants as they vary over time and water-bearing characteristics of the ground water space. system have been adequately described, the modeler uses equations to show, for example, how water Because ground water flow is a major factor af- naturally enters the system from infiltration of rain- fecting the movement of contamination, pollutant fall or streamflow, how water naturally escapes from transport models are necessarily extensions of the system through discharge into surface water ground water flow models. As a result, a contami- bodies or through consumption by vegetation, and nant transport model is, at best, as reliable as the how the extraction of water from wells affects the ground water flow model to which it is coupled. overall water balance. For small-scale contamination problems in material that is highly variable or is fractured, estimates of The response of a ground water system depends ground water flow may be inaccurate, thereby re- not only on hydrological conditions, but also on the ducing the reliability of transport estimates. manner in which the ground water is withdrawn for use. For example, locating wells too close to each In addition to ground water flow, the movement other may cause large water-level declines near the of pollutants is affected by mixing and by chemical well field, resulting in reduced yields, dry wells, or processes, both of which are poorly understood. even subsidence of the land surface. Ground water Since quality problems are more complex than flow models can be used to address problems such quantity problems, models dealing with ground as the optimal design of a well field and the extent water quality are generally less reliable than those of available supplies, and to predict water-level de- for ground water quantity. Quality models are also clines due to alternative development schemes. considered less credible than quantity models because of their recent origin and the relative unavail- Although the most frequent use of ground water ability of validated models. flow models is for water-supply management, these models can be helpful throughout the planning Ground Water Quantity Issues stages preceding management decisions. Models also provide a framework and guide for collecting Available Supplies and Optimal Yields and organizing data. By matching computed model Models are well suited for determining the hydro- results with observed system behavior, one can gain logic limitations on ground water availability, or a better understanding of hydrologic and geologic on the yield of an aquifer. Hydrologists have devel- conditions. Even with limited data, the hydrologist oped several definitions of what constitutes an aqui- may use a model to test alternative hypotheses of fer’s yield. One definition, “sustained yield, ” rep- how the system behaves. resents the maximum amount of water that can be For managing, regulating, and planning the use removed from the system if inputs and outputs are of ground water, models that determine available to be balanced, with no net loss from the aquifer. supplies and optimal yields are highly reliable. The concept is based on the commonsense obser- However, since ground water data are derived pri- vation that water cannot be continually withdrawn marily from wells, aquifers that are relatively unde- from wells if the rate of withdrawal exceeds the veloped often have an inadequate data base for esti- natural rate of replenishment to the ground water mating potentially available yields. As the system system. A second definition, ‘ ‘optimal yield, in- is developed, more data become available, and ear- corporates political and social considerations, and lier modeling efforts can be modified to reflect this refers to an optimal plan for using a ground water additional information. Thus, data collection and system, whether on a sustained basis or not. This modeling activities must be coordinated with aqui- approach attempts to maximize economic objectives fer development if reliable information about the and to minimize environmental impacts through ground water system is to be available when it is legal and social constraints on the use of the ground most needed—when water withdrawals are large water supply. enough to significantly affect the aquifer. Ch. 6—Modeling and Water Resource issues ● 147

Conjunctive Use of Ground and Surface Waters Subsidence of the Land Surface Aquifers are commonly hydrologically connected Under certain geologic conditions, particularly to surface lakes and streams. Ground water fre- where thick beds of clay underlie the land surface, quently provides the base flow to streams—the heavy withdrawals of ground water may lower streamflow that occurs even during dry weather. ground water levels to such an extent that the clays During periods of low rainfall, the base flow pro- partially dry out. In some situations these clays vided by ground water is a major determinant of shrink or compact, resulting in settling or subsi- both the quantity and quality of surface water. A dence of the land surface, which may cause rup- decline in ground water levels may decrease the tures in pipelines, cracking of building foundations, base flow and degrade surface water quality. In or even surface water floods. The Houston Ship other situations, surface water may recharge the Channel in Houston, Tex., is a notable example— ground water system. In this case, a change in the several adjacent residential communities have es- quantity or quality of the surface water would af- sentially been abandoned because flooding by tidal fect the ground water. waters has resulted from land surface settlement. Conjunctive use models analyze the interaction To model these conditions, data are needed not between ground and surface water systems. These only for the ground water system itself but also for models may provide information about both quan- soil mechanics and physical properties of clay soils tity and quality aspects of surface water and ground under dry conditions. In addition, information is water interrelationships, and can be used to aid in needed about the surface water systems in areas the combined management of both water sources. where subsidence may alter drainage areas and flow Ground water flow models have been employed for patterns. many different conjunctive-use situations. A typical problem of this kind involves determining the ef- Ground Water Quality Issues fects on surface water flows of irrigating with pumped ground water distributed through irriga- A basic understanding of ground water flow is tion systems. The ground water flow models used necessary for understanding ground water quality for these applications are essentially the same as problems. Since pollutants entering a ground water those used to determine optimal yields. For con- system are carried along with the water flow, many junctive use, however, the components of the model of the factors that determine quantity relationships describing the interaction between ground and sur- also apply to quality models. Problems of ground face waters become critical and are consequently water quality are likely to dominate water resource more complex. issues in the 1980’s. They fall into four broad cat- During the past decade, ground water flow mod- egories: 1) accidental and negligent contamination els have frequently been used to solve conjunctive from urban and industrial areas; 2) agricultural use problems. Model reliability is nearly as high pollutants to ground water; 3) movement of pol- as for ground water supply and optimal yield ap- lutants into and through ground water from waste plications; confidence is somewhat reduced, how- disposal; and 4) seawater intrusion. ever, because quantitative estimates of the interac- The disposal of wastes, in particular, involves tions between ground and surface waters are diffi- major political issues for which the analytical capa- cult to obtain. Furthermore, the scale of the sur- bilities of models will be useful. Wastes can be dis- face water problem (i.e., area of influence and speed posed of in the atmosphere, in streams and other of water movement) may differ from that of the as- surface water bodies, or into or on the solid earth. sociated ground water system. This may result in Each of these options has associated tradeoffs. In- an accurate description of the ground water re- land and onland disposal of either solids or liquids sponse but a less satisfactory description of local may contaminate ground water and cause wastes surface water responses. to be transported long distances from the original 148 ● Use of Models for Water Resources Management, Planning, and Policy disposal site. Consequently, ground water hydrolo- cal conditions. Contaminant transport models, in gists are being asked to predict the movement of conjunction with careful hydrologic studies, can contaminants to aid in designing waste-disposal provide important information on alternative cor- systems to minimize contamination. The problem rective measures. is perhaps best exemplified by the present search This section deals with unintentional, nonagricul- for a geologic disposal site for high-level radioac- tural contaminants to ground water. Three fre- tive wastes. quently occurring pollutant types will be discussed: 1) petroleum products; 2) industrial chemicals; and Accidental and Negligent Contamination 3) road salts. For each of these, contaminant trans- From Urban and Industrial Areas port models can be used with varying degrees of success and confidence. Model capabilities are lim- Unintentional ground water pollution is reported with increasing frequency. Regulatory agencies ited primarily by insufficient data on and under- have particular difficulty in planning for emergency standing of the movement of contaminants through incidents of ground water pollution, due to the wide soil and rock. It is often necessary to drill numerous variety of possible contaminants and hydrogeologi- sampling wells to determine the extent of the contamination. Other information that is needed includes the amounts of contaminants released and 11 -M / the chemical reactions occurring in the soil. Petroleum spills and leaks are serious sources of ground water contamination. Hundreds of thousands of gasoline storage tanks, thousands of miles of underground pipelines, and numerous tank trucks and railroad cars carry oil or gasoline throughout the country. Contamination from these sources is quite difficult to analyze with models. Models of the movement of oil or gasoline have been routinely employed for petroleum reservoir engineering, but have had limited application to ground water problems. Insufficient experience with these models limits their use for analyzing contaminant transport. P

Photo credits: @ Ted Spiegei, 1982 Extensive ground water withdrawal can cause land to subside on small or large scales. At left, signs on telephone poles in the San Joaquin Valley, Cal if., show the sinking of the Earth’s crust as a result of ground water use for irrigation since 1925. Florida sinkhole at right demonstrates a more dramatic local effect. At any scale, land subsidence in inhabited areas has enormous destructive potential; developing models to estimate the conditions under which subsidence will occur requires extensive knowledge of geology, ground water hydrology, and soil sciences Ch. 6—Modeling and Water Resource Issues ● 149

Although oil and gasoline do not generally mix gated with both surface water and pumped ground with water, small concentrations of petroleum prod- water. As the water flows through the ground and ucts may dissolve. These low concentrations may returns to the stream, it accumulates salts from the exceed acceptable water pollution standards. The soil that are further concentrated by evaporation movement of dissolved oil or gasoline can be ana- from soil and plants. The water returning to the lyzed by contaminant transport models once the stream often has high salt concentrations and is nature of the dissolution process is known. These sometimes unusable for irrigation by farmers down- models can be used to gage the effectiveness of var- stream. ious cleanup procedures. Salt buildup can also occur as a result of fertiliz- Toxic industrial chemicals can accidently contami- ers, and, to a lesser extent, from storage or disposal nate ground water supplies in a number of ways— of livestock wastes. Fertilizer is a serious source of leaky storage tanks, tanker spills, or leaky holding pollution. Nitrates— a major component of fertilizer ponds. The range of possible contaminants makes and a type of salt —are the most common cause of it difficult to use models to predict resulting pollut- ground water contamination beneath agricultural ant concentrations. In general, for chemicals that lands. dissolve in water but do not react with soil or rock, credible models can be developed if sufficient hydro- The use of pesticides and herbicides has expanded logic data exist. However, for chemicals that are significantly in recent years, When pesticides and either immiscible with water or reactive with soil herbicides are applied to the land, they migrate or rock, model reliability will be low, regardless of downward toward ground water supplies through the amount of hydrologic data available. Still, for the unsaturated zone. They generally move slow- such reactive constituents, conservative or ‘ ‘worst- ly, and undergo chemical changes in the unsatu- case’ predictions can be useful for assessing the rated zone that alter their properties. Pesticides and maximum pollution potential, and can be generated herbicides that are “broken down’ in this man- by assuming that no reactions occur. In these cases, ner are often not harmful when they reach the model results can aid in evaluating alternative ground water. However, the greater the use of pes- remedial measures. ticides and herbicides, the higher the likelihood of producing concentrations exceeding the biodegra- Large quantities of salts are applied to roads dur- dation capabilities of the unsaturated zone. Serious ing icy conditions, primarily in Northern States. ground water pollution can result in such cases, Road salt is highly soluble in water; thus, shallow ground water supplies near major roads may be- Models of ground water flow and transport come contaminated. In recent years, recognition through saturated soil and rock are generally of this problem has led to decreased usage of road reliable when applied to these problems. Water salt. While contaminant transport models can assess quality variations in an irrigated stream-aquifer the potential for ground water pollution from road system can be reliably predicted with mathematical salt use, the problem is not generally considered models, if sufficient data are available. serious enough to warrant the collection of the expensive field data needed to produce credible re- Flow and transport in unsaturated zones are less sults. well understood; consequently, unsaturated flow models are less reliable than saturated ground water Agricultural Pollutants to Ground Water models. As yet, no model has been developed that incorporates all the physical, chemical, and biologi- Agriculture, because it is so widespread an activ- cal processes occurring in the unsaturated zone. ity, is an important influence on the quality of However, many problems involving pesticide-her- ground water. Agricultural activities can affect bicide ground water contamination can be analyzed ground water quality through: 1) salt buildup, and without a comprehensive model, Simplified models 2) contamination by herbicides and pesticides. are useful for assessing the effectiveness of the un- Salt buildup is caused in two ways. In semiarid saturated zone as a barrier to potential pollutants. regions, fields close to streams are commonly irri - Results based on conservative or worst-case as- 150 ● Use of Models for Water Resources Management, Planning, and Policy — sumptions may be helpful for determining the ef- and few have means for monitoring ground water fects of agricultural practices on ground water. quality. Contaminants that seep from impoundments Movement of Pollutants Into and Through may be modified in the soil by various chemical Ground Water From Waste Disposal reactions, thus reducing their harmfulness; others Several methods are commonly used for onland may move into shallow ground water and cause pol- waste disposal: lution. Studies generally show that ground water contamination creates a contaminant plume that ● landfills; may be well contained locally, but might extend . surface spreading; up to a mile or more from the impoundment, de- . surface impoundments; and pending on ground water conditions. ● injection wells. Actions that can be taken to alleviate contamina- Approximately 5 pounds of solid wastes per per- tion of ground water include: son are produced daily in the United States. Solid waste is normally reduced in volume by compac- ● lining the impoundment with plastic, impervi- tion and placed in landfills, which currently number ous clay, asphalt, or concrete; over 150,000 in the United States. When rain enters ● constructing collection systems such as wells a landfill and infdtrates through the refuse, byprod- for recycling; and ucts of waste decomposition dissolve in the water, ● reducing the movement of contaminated producing a liquid known as leachate. Leachate can ground water by means of hydraulic or phys- be a serious problem in nonarid regions, where ris- ical barriers. ing water tables infiltrate refuse, causing contami- The effectiveness of these actions can be evaluated nants to migrate into the ground water system. with mathematical models. The approach to analyz- Such leaching of pollutants may continue for dec- ing contamination from impoundments is similar ades or even hundreds of years. Models can be used to that used for landfills. to predict the effects of alternative engineering designs on the landfill hydrology, and to predict Wastewater injection wells offer an alternative to the transport of leachate into ground waters. These disposal of waste at or near the land surface. As models are still in initial stages of development. of mid- 1973, at least 278 industrial wastewater injection wells had been installed in 24 States, and Much domestic waste in the United States is 170 of these wells were operating. Most were be- processed in secondary sewage treatment plants. tween 1,000 and 6,000 ft deep and had average in- A common practice for disposing of these waste by- jection rates of less than 400 gallons per minute. products is to spray liquid sewage on and spread As with other pollution problems, chemical and bio- sludge over the land surface. Surface spreading of logical reactions occurring within injection wells are sewage and sewage sludge may degrade ground the most difficult to model accurately. Nonetheless, water quality, both through salt buildup and from models may still be used to estimate the impact of heavy metals that are not removed during second- the injection system on the natural hydrology; this, ary treatment. Since this practice is similar to fer- in turn, may be used to design well fields and injec- tilization, modeling capabilities and difficulties are tion schemes. similar to those described for agricultural practices.

Surface impoundments are pits, ponds, and lagoons Seawater Intrusion in which liquid wastes are stored, treated, and disposed of. These wastes contain a wide variety of Cities in coastal areas often withdraw large quan- organic and inorganic substances. Over 170,000 tities of ground water for their freshwater supplies. impoundments are located in the United States— This decreases the seaward flow of freshwater, many of them contain potentially hazardous wastes. which may cause saltwater to move into ground Few of these impoundments have a bottom liner, water reservoirs. Ch, 6—Modeling and Water Resource Issues 151 ——

The movement of seawater into drinking water general level of model development in each cat- supplies in coastal areas is a serious and widespread egory, rather than for any specific model. A com- problem. Models can aid in designing well fields prehensive list of models available for ground water and pumping schemes to minimize seawater intru- analysis is provided by Bachmat, et al. 1 sion. However, for cases in which the hydrology Two major criteria are used to evaluate each is complex, such as a layered ground water system model category: 1) model reliability; and 2) credi- in which flow characteristics among the layers vary bility of model results. Models are considered reli- greatly, modeling results are less reliable. able if they can accurately describe the important chemical and physical processes. Credible results Evaluation of Currently Available require both a reliable model and sufficient data Ground Water Models to run that model. For some applications, models may be reliable, but the cost and difficulty of col- In table 9, models that can be applied to each of the problems previously described are evaluated IY. B. Bachmat, et al. , ‘ ‘Utilization of Numerical Ground \\’atcr according to model types employed and the models’ Models for Water Resource Management, ” U.S. Environmental Pro- areal scale of analysis. The evaluations are for the tection Agency, report No. EPA-600 /8-78-Ol 2, 1978.

Table 9.—Ground Water Model Evaluation

Model types spatial Considerations Site Local Regional

Transport Transport Transport Transport WIO Transport WI Wlo WI Wlo Pollutant movement, if any Flow only reactions reactions Flow only reactions reactions Flow only reactions un sat sat sat multi sat sat :;t sat sat M sat sat sat sat sat sat sat sat sat sat Fiow conditions P F p fluid P F F’ P F P P F P F p F p F p F

Issues Quantity—available supplies. . . . . B c A B B B

Quantity—conjunctive use. B R A B B B Quality —accdental petroleum products...... R B c R c R

Quality—accidental road salt, . . . . B c c Quality—accidental industrial chemical ...... B c c c R – B c c – Ouality—agricultural pesticides and herbicides...... B c c c R – B c c –

Quality–agriculture salt buildup. . B c c B c

Quality—waste disposal landfills. B c c c R – B c c –

Quality—waste disposal injection. B c c c R – B c c –

Quality—seawater intrusion...... B B c c 0 c c c Key Rows — issue and subissue areas discussed in text Columns — model types and scale of applications; e g, the sixth column applies to a site-scale problem in which Pollutant movement IS described by a transport model without chemical reactions under saturated flow condltlon in fractured media Application scale Site—models delaing with areas less than a few square miles Local—models dealing with areas greater than a few square miles but less than a few thousand square miles Regional—models dealing with areas greater than a few thousand square m!les Abbreviations w/—with w/o—without. sat—saturated ground waterfiow conditions unsat —unsaturated flow conditions P—porous media F—fractured or solution cavity media Entr!es A a usable predictive tool having a high degree of rellablllty and credlb!l!ty given sufficient data B a reliable conceptual tool capable of short.term (a few years) prediction with a moderate level of crediblltty gwen suff!ctent data C a useful conceptual tool for helping the hydrologist synthewze complicated hydrologic and quality data R a model that IS still In the research stage — no model exists Blank—model type not applicable to issue area 152 . Use of Models for Water Resources Management, Planning, and Policy

lecting data may prevent calculated results from Models rated ‘‘C” have not been sufficiently val- being very credible. The ratings assigned for each idated for analyzing specific problems. Both expen- model category are a composite of these two con- sive data collection and inadequate understanding siderations. of important processes are likely for these models. Models with “C’ ratings have utility as concep- The key at the bottom of table 9 describes the tual tools for investigating general problems. terms employed, and briefly summarizes the model rating scheme, the breakdown of model types, and Models having a rating of “R” are still in devel- the measurements used to define different levels of opmental research stages. In the future, these mod- scale. Explanations of the rating scheme, and of els should earn a higher rating as they are validated scale and time considerations in model evaluation, through field use. are provided below: Models described by “-” are not presently available. Model Rating Area/ Scale. The credibility of ground water A rating of‘‘A ‘‘ indicates that models are reli- models is highly dependent on the geographic scale able and can be applied with credibility to a par- of the study area. Most models are designed to op- ticular problem. It also implies that data necessary erate at the local scale (area greater than a few to use the model can be obtained at reasonable square miles but less than a few thousand square costs. Models with ‘ ‘A’ ratings can be used effec- miles). Therefore, more confidence may be placed tively for making decisions on applicable problems. in models used for this scale. Models rated “B” can be used for short-term Time Scales. Ground water models project future predictions with confidence. The lower level of cred- conditions for widely varying intervals of time. ibility implies that either some part of the processes Generally, the longer the range of the prediction, described is not fully understood, or that data nec- the less reliable it is. Ground water models normally essary to use the model may be too expensive or involve planning horizons of 20 to 30 years, and too difficult to obtain. These models can be applied each model varies in its ability to forecast future to field problems if their limitations and capabilities conditions. For many hazardous waste problems, are recognized. Further, if field data were collected the time frames needed are much longer, sometimes on a continuing basis and incorporated into the ranging to hundreds of years. Results from such model, model credibility would improve. Models projections are much less credible than results from with “B” ratings can also be used to investigate models used for problems with shorter time frames. general problems (but not specific field applica- While time frames are not specifically considered tions). Conceptual investigations can be used in in the evaluations, the effects of different time pro- designing regulations and policy, e.g., for deter- jections on the credibility of model results must be mining landfill siting criteria. considered in evaluating specific models.

ECONOMIC AND SOCIAL MODELS

Introduction using theories drawn from economics, sociology, social psychology, geography, and political science. Many different types of models and analytic techniques are used to determine the economic and Economic models are used to estimate the overall social consequences of water resource activities, to effects of water resource activities and regulations forecast consumer and industrial water needs, and at both the regional and national levels, as well as to analyze water resources for comprehensive river to forecast economic consequences to individuals basin planning and management. Social and eco- and firms. For example, an economic model can nomic models address patterns of human behavior forecast changes in an industry’s water use as the Ch. 6—Modeling and Water Resource Issues ● 153

cost of obtaining water changes, and determine the to incorporate in a model except in an abstract effect of such changes on industrial output. way—identifying behavioral tendencies with in a probability of outcomes. Another problem, more Social models can project population trends, esti- prevalent among social models, is that they are mate water demands, and analyze the social struc- data-limited. Available data often prohibit quantify- ture of a given area. They can be used to identify ing and analyzing all factors involved in determin- the groups likely to be affected by resource deci- ing the ‘ ‘public interest ‘‘ in any given situation. sions, and their perceptions of these effects. Social Thus, ‘ ‘decision’ models of social and economic models can be coupled with economic models to factors can only be used as guides—they cannot be evaluate the societal implications of water resource substituted for the human decisionmaking process. regulations or projects. Because of the difficulty in evaluating social sci- The use of social and economic models is relative- ence models, and their less advanced state of devel- ly new in the water resources field, as in other fields. opment, these models were not formally evaluated. Social and economic model use in water resource Few social science models are widely adaptable; analysis has been prompted by two major regula- moreover, such models are difficult to validate by tions: 1) the Principles and Standards (P&S) of the comparing predictions to results, as is routinel Water Resources Council; and 2) the National En- y done for models of physical processes. Assessing the vironmental Policy Act of 1969. The P&S are a relative utility of these models requires comparisons group of publications that presently require con- of previous model applications under a variet of sideration of the likely effects on environmental y conditions by different analysts, and necessaril in- quality and national economic development of proj- y volves a considerable component of subjective anal- ects proposed to receive full or partial Federal fund- ysis. ing. The P&S also require studies of the effects of proposed projects on regional development and on the social well-being of the affected area. The Na- Basic Analytical Characteristics tional Environmental Policy Act requires estimates Social science models are classified by the kinds of the social and economic effects of proposed proj- of information they generate. Three major distinc- ects. To make such estimates, social models can be tions are used to identify significant characteristics: used to identify the population that would be af- 1) descriptive v. normative; ‘2) macroscale v. micro- fected by the resource decision, and the extent of scale; and 3) efficiency v. distribution of costs and the likely effects. Economic models are also em- benefits. ployed to determine the economic impacts of a project on individuals, firms and the region overall. 1. Perhaps the most important dimension involves the distinction between descriptive and norma- Several factors account for the increasing use of tive models. A descriptive model is an empirical social and economic models. Models may provide and historical representation of ‘what is. De- the only available means of organizing complex in- scriptive models determine factual relationships formation for examining the effects of an action or as they exist or may be expected to occur. They policy. Information derived from the conditions and are intended to include a minimum of subjec- scenarios assumed in a model can provide insights tive assumptions and biases. about the effects that may occur, and serve as a A normative model may be equally reliable and basis for common discussion of assumptions and credible, but it focuses deliberately on ‘‘what probable outcomes. Finally, social and economic should be. Normative models include substan- models can be used to compare the merits of pro- tial judgments and assumptions about goals and posals in terms of a particular objective, and help objectives. For example, a descriptive model of decisionmakers determine the costs and benefits of the Nation’s economic output would simpl re- a proposed decision. y port actual or expected levels of gross national

Both social and economic models are limited by product (GNP), while a normative model might the necessity of dealing with human behavior, include the assumption of a 5-percent annual in- which is not always predictable. Behavior is difficult crease in GNP as an economic goal. Most of the Photo credit: U.S. Department of Agr/cu/ture Water resources development can have tremendous effects on an area’s ability to attract residents, industry, and related activity. Models are available to estimate how construction expenditures may directly affect local or regional economies, as well as how water facilities could affect subsequent development. In addition, models can describe how water- related development could affect demands for a wide range of public services, for example, schools, hospital facilities, roads, and other infrastructures

current social and economic models used in Microscale models focus on individual and/or water resource analysis are normative, i.e., sub- enterprise-level behavior. They are often used stantial a priori value judgments have been made in water resources for feasibility studies, environ- about the goals, objectives, measures, and meth- mental impact statements and other project-plan- ods used in the model. ning activities. Microscale models are used to address, for example, pricing, benefit/cost, social 2. Scale is the second feature by which social sci- impact, and risk/benefit questions. ence models can be categorized. Two distinct types are recognized—macroscale models and 3. A third feature of social science models addresses microscale models. Macroscale models address ag- the dual questions of efficiency and distribution of gregate changes or activities. Macrolevel models costs and benefits. Water resource policies or activ- include those that measure and forecast trends ities affect both economic efficiency and the dis- such as levels of national economic activity (e. g., tribution of costs and benefits. Efficiency is de- GNP), money supply, international trade, mi- scribable by economic models, while addressing gration patterns, etc. They are useful for pro- the distribution of benefits requires a broader viding national and regional analyses of water social analysis, Models of economic efficiency resource projects and programs. focus on means of increasing the gross supply Ch. 6—Modeling and Water Resource Issues ● 155

of goods and services. Distributive models trace 4. The fourth class of models is referred to here as changes in assets and/or income distribution simulation models. Economic simulation models among either resource owners (e. g., labor, cap- are often input-output or econometric models ital, management) or major sectoral groups that are adapted to examine the implications of (e. g., farmers , industrial workers, the unem- different sets of assumptions. Simulation models ployed). describe the highly involved pattern of cause- and-effect relationships that operates within most Types of Models Used social or economic systems. Once relationships for Economic Analysis are identified and the key factors have been quantified, the model is used to simulate the Four types of economic models are widely used performance of a system over a period of time, for dealing with water resource issues: 1) input- under different sets of assumptions about the output; 2) optimization; 3) econometric; and system’s internal relationships and the values of 4) simulation. external variables. Such models can calculate the incremental effects of price changes or im- 1. Input-output models are based on a detailed ac- provements in production methods, for example. counting of sales and purchases among each of the industries or sectors being studied. Informa- tion on purchases and sales is used to determine Other Social and Economic either the requirements for particular inputs Analytical Techniques (e.g., water) or the production of outputs (e. g., manufactured products). In addition to traditional economic analysis and the four model types identified above, an increas- 2. Optimization models are used to determine the allo- ingly large set of social and economic analytical cation of resources that best meets a previously methods is being used in natural resource planning specified objective (e. g., least cost), subject to and policy evaluation. The methods are diverse, some specified constraints. The technique is par- so they will be discussed here according to the kinds ticularly well suited, therefore, to solving prob- of relationships they are designed to explore. lems where both the objectives and the constraints are clearly defined. When more than one A major consideration in planning and policy objective is considered, these models can describe analysis is the size and demographic structure of the the tradeoffs between the best solutions for each population. Demographic models, therefore, relate respective objective. information about the present size and structure of the population to projected changes due to births 3. Econometric models are a less homogeneous group and deaths or to population shifts. Most of these than the two previously discussed classes of mod- models deal with specific age, sex, and racial groups els. The term is generally used to describe fore- or cohorts, and are consequently referred to as co- casting models, the structures of which have been hort survival models, carefully estimated from historical data. The large, national forecasting models (e. g., Chase, Another set of analytical techniques has been de- Wharton, Data Resource, Inc. (DRI), etc. ) are veloped to deal with the demands for, and supply of

of this type, as are many models tailored to infrastructure—factors such as housing and public regional and State needs. Econometric models facilities and services. These techniques are used are typically based on the following macroeco- by planners to determine the fiscal impacts on gov- nomic principles: 1 ) production determines in- ernments —including both expenditures and collec- come; 2) income determines demand; and tion of revenues—of providing various levels of in- 3) production, in turn, adjusts to demand. The frastructure services, Standard models are available interactions among production, income, and de- to carry out these infrastructure and fiscal impact mand determine economic multiplier effects, calculations, although variations among jurisdic- which play an important role in economic im- tional units require adjustment for the particular pact analysis. unit of government being considered. 156 . Use of Models for Water Resources Management, Planning, and Policy

Once economic, demographic, and public sec- affect that use. Using statistical analyses, the ef- tor behavior has been accounted for, a major re- fect of price can be isolated from the effects of all maining concern is the social structure of an area. Few other variables influencing residential water use. computer models have been developed to analyze The models analyze actual consumer responses this problem, but progress is being made in defin- to water prices. However, because responses to ing social structure, and in understanding how it prices vary among regions and among income is affected by natural resource decisions. groups over time, model estimates will be region-, The final major area of activity for socioeconomic time-, and income group-specific. These models are analysis is the integration of the various economic useful planning tools, provided that adequate data and social concerns discussed above. The models are available and that analysts recognize the theo- discussed above provide measures of change in the retical and statistical assumptions underlying the economic, demographic, fiscal, and social environ- model. ment. However, the significance of these changes Industrial and agricultural! water demand can also be ultimately depends on the perceptions and values analyzed with mathematical models. Because large of the people who will be affected by them. Cur- water users are often self-supplied, market prices rent research is underway in identifying groups that for water in the conventional sense do not apply. may be affected by resource decisions, and deter- However, analyses for these demand sectors are mining their evaluation of the social and economic based on the costs borne for using water. These changes that may affect them. Methods for quanti- models consider the objectives and constraints that fying these analyses, however, are in relatively early govern agricultural and industrial decisions about stages of development. levels of production and amounts of raw materials to be used, including water. The influence of water Economic and Social Issues price on use is inferred by examining the models’ in Water Resource Analysis predictions of water use changes as water costs change. Effects of Water Pricing on Use These models are not based on observed re- Severe water shortages in many locations have sponses to price change. Rather, they are simula- prompted investigation into strategies for reducing tions of responses that could be expected from ‘ ‘ra- the demand for water. Water use restrictions have tional’ water users with objectives and constraints commonly been used for managing water use, but similar to those described in the model. To the ex- other methods that rely on economic incentives tent that water users deviate from the objectives and (water pricing and conservation subsidies) have constraints assumed in the model, model predic- potential for reducing the consumption of water tions will be inaccurate. A number of these models through nonregulatory approaches. have been developed; however, their use requires Water demand models, which predict the re- highly skilled analysts and good data bases. sponse of water demand to changes in water costs, Both types of water demand models are useful have been developed for residential, industrial, and tools for water resource decisionmaking. If properly agricultural uses. The cost of using water, as con- developed, they can organize complex information sidered by these models, includes both prices paid about the factors that determine water use, and as- for water delivery and other acquisition and use sess the importance of price relative to other fac- costs, such as costs of disposing of used water. tors in determining use. Information provided by Residential/ water demand models are based on ac- such models is helpful for developing demand man- tual household water use behavior. Consumer de- agement strategies, including changes in prices of mand theory suggests that the quantities demanded publicly supplied water (e. g., at municipal systems are related to water price, consumer characteristics or Federal irrigation projects) or marketing of water (income, family size), and factors such as the rights, where market prices are determined by will- season, and extent of outdoor use. Data are col- ing buyers and sellers. These models are useful for lected on household water use and on factors which comparing alternatives, but are less reliable for pro- Ch. 6—Modeling and Water Resource Issues 157

vialing quantitative estimates of actual volume de- er interpretation of the results can provide estimates mands. of the costs that firms incur as a result of regulations. Limitations and potentials of this type of Cost to Industry of Pollution Control model are similar to those of water demand models. Models of this type are used for determining the Pollution control costs, like the availability and least-cost approach to environmental regulations. cost of water, are one of many factors affecting the These models have been used to a limited extent profitability and location of industrial activity. by EPA in the water quality regulatory process. It Models are used to determine the effects of regula- is likely that greater use of these models will be tions on specific industries, as well as the impact made in the future, for reviewing existing or pro- of pollution control policies on the economy as a mulgating new environmental regulations. whole. Costs of pollution control can be assessed at both macroeconomic and macroeconomic levels. Macroeconomic costs are those associated with a Benefit/Cost Analysis particular firm or industrial group, and include di- Benefit/cost analysis measures the value of a pol- rect expenditures for pollution control equipment, icy, program, project, or regulation in terms of eco- costs of changing production processes, and fore- nomic efficiency. Procedures for calculating the gone production. Macroeconomic costs are gaged benefits and costs of Federal water resource activ- by calculating the effects of industry expenditures ities are outlined in the P&S of the Water Resources to meet environmental regulations on employment Council. levels, the Consumer Price Index (CPI) and GNP. A relatively small portion of Federal activities in Macroeconomic models are the most complex of water resource protection and development is now all economic models. Their development and use covered by the P&S. Affected agencies (principal- requires highly skilled personnel. For example, the ly the Corps of Engineers, Soil Conservation Serv- models of DRI, and Chase Econometrics, Inc., ice, Bureau of Reclamation, and Tennessee Valley which are among the best known of this type, have Authority) prepare estimates of some costs and ben- been used to evaluate changes in macroeconomic efits of their proposed investment projects. How- variables in response to industry expenditures for ever, some of the most common Federal activities compliance with environmental regulations. How- —e. g., waterway and discharge permits, and sew- ever, some analysts consider it inappropriate to use age treatment construction grants—are not re- these models to measure ‘ ‘costs of pollution con- quired to prepare benefit/cost analyses. trol. While the models can predict movements in the CPI or GNP, they do not estimate the economic Although economists have developed rigorous value of a cleaner environment (e. g., reduced health theoretical standards for determining the proper care costs, workdays lost due to illness, etc. ) as an measure of both costs and benefits, even the most offset to the cost of pollution control equipment. competent analysts face difficulties in conducting The reliability of these models is difficult to test; sound benefit/cost analyses. Many costs and bene- their use depends largely on the plausibility of as- fits may be known, and yet be difficult to define sumptions made about inputs and the lack of credi- or quantify accurately— in water resource activities, ble analytical alternatives. more incommensurable benefits tend to be encountered than incommensurable costs. Construction A4zc~oecomrnic moa!ds of costs to industry for pollu- costs for building a dam or a sewage treatment tion control are most often optimization models, plant, for example, are easier to estimate than the similar to those described in the above section on value of decreased likelihoods of flooding, or the water demand. Models of this type can be devel- value of cleaner water to downstream users. oped for ‘‘typical firms ‘‘ in specific industries. A baseline condition is first determined by applying When no professional consensus exists as to the the model without environmental regulations. Envi- monetary value of a benefit, or the probable cost ronmental regulations are then introduced as a con- of an activity, standards of accuracy for benefit/cost straint on the firm’s resources and outputs. Prop- analysis are difiicult to establish. Estimating the val- —

158 Use of Models for Water Resources Management, Planning, and Policy ue of less tangible benefits necessarily involves an analysis is useful for comparing and screening alter- element of subjectivity; consequently, such esti- natives according to their relative contribution to mates are affected by the assumptions of the analyst. the Nation’s economy. The choice of a particular time frame or discount rate, for example, while not imparting intentional Implications of Water Resources Policy bias, may heavily influence results. for Regional Economic Development As a general rule, benefits and costs of public The regional economic impact of water resource projects are easiest to evaluate when the resources, development is an important concern that is not goods, or services produced are traded in the considered in ‘‘standard’ benefit/cost analysis. To market economy (e. g., power production). Benefits the locality or region in which a water project is and costs are less easy to measure if the resource, proposed, the regional economic effects may be as good, or service either contributes directly to a good important as the costs or benefits to the nation as which is traded (e. g., irrigation water as a factor a whole. in agricultural production), or if the private market Models have been developed that estimate offers a comparable substitute for the public proj- changes in the level of local or regional economic ect’s output (e. g., railroad transportation as a activities (employment or income) and/or economic substitute for river transportation). Benefits and base (development potential) due to projects or ac- costs are very difficult to estimate for resources, tivities. Standard models include various forms of goods, or services for which few market transac- simple economic base studies, as well as the more tions exist (e. g., recreation, wildlife habitat). In complex input-output models. these cases, the economic value of the public project cannot be inferred from observed market prices. In the past decade, advances have been made in regional development models for analyzing eco- Institutional limitations on the alternatives that nomic, demographic, and community effects associ- can be considered for achieving an objective consti- ated with water resources development. The Bu- tute another constraint to effective use of ben- reau of Reclamation, for example, has developed efit/cost analysis for Federal water activities. the Bureau of Reclamation Economic Assessment Benefit/cost analysis is most useful when it is used Model, an economic/demographic simulation mod- as a screening device for comparing alternatives. el used in both planning and impact assessment pro- If an agency, for example, is restricted to funding cedures. Similar tools are used by the Corps of En- flood control structures and cannot propose pur- gineers and by regional and State water resource chasing flood plain development rights as a non- agencies. structural alternative, the full power of the analytical technique cannot be effectively used. These models are used to evaluate the economic effects of direct expenditures made in a region to Benefit/cost analysis is often used to support nor- implement a program or build a project, and the mative arguments that no actions should be taken continued effects of the spending generated by these unless benefits exceed costs. However, such argu- activities. Such models simulate a complex and dy- ments are often rejected for two reasons: First, com- namic process, accounting for multiplier effects plete measurements of economic efficiency, bene- from expenditures made in direct support of the fits, and costs of public actions are limited by data activity (wages paid to labor, goods and services and time for conducting the analysis. Therefore, purchases locally, etc.), and assist in comparing the a benefit/cost analysis will often not reflect all impacts of alternative programs and projects on the economic benefits and costs. Second, economic effi- regional economy. Such comparisons can be of valu- ciency in resource allocation is only one of several e for both planning and policy. possible aspects of the “public interest” which must guide decisions. For example, the distribution of The use of these models is feasible for most skilled these benefits and costs among the public can be analysts. The Water Resources Council has pub- considered as important as the relative amounts of lished multipliers developed by the U.S. Depart- these benefits and costs. Nonetheless, benefit/cost ment of Commerce for simulation purposes. How- Ch. 6—Modeling and Water Resource Issues ● 159 ever, developing the models and multipliers them- little assistance to the decisionmaker, since it does selves requires special skills and extensive data. not indicate why water use changes over time. The results of these models must be carefully in- To remedy these shortcomings, more complex terpreted. Such models are based on data that rep- economic forecasting models have been developed. resent the existing regional economy. If the water Complex models are simply applications of the resource activity being evaluated significantly alters water demand models described above. First, the the region’s economic structure, the model may be demand models are used to determine the relative invalid. The smaller the public action relative to importance of the various independent factors the regional economy, the more reliable model re- (price, income, technology, etc. ) that determine sults will be. Moreover, these models should not consumption levels for each major category of water be used with the implicit assumption that economic user. Second, future changes in these factors are activity (e. g., a new industry) will be attracted to projected and incorporated into a demand model the area solely on the basis of increased water re- to predict future demands for water. A disadvan- sources development. Many economists consider tage of the complex model approach is that it re- water projects to be uncertain means for redistribut- quires projections into the future for many factors, ing income, stimulating regional development, or a difficult task requiring a large, credible data base. achieving employment stability. Water use projections are only guides—’ ’best Clarification of the regional economic stake in guesses’ about an uncertain future. The demand water development has been and can be further model approach does, however, serve a useful role aided by careful model use. This type of analysis in planning and policy. Models can be used to test is best suited to planning activities, such as com- the sensitivity of forecasts to different assumptions paring scenarios for different alternatives. If such —e. g., they can identify and assess the conse- models are used to estimate impacts with more pre- quences of overinvestment or underinvestment in cision, they should only assess the impact of cer- water supply capacity. tain, direct expenditures resulting from the public action, and only for short (1- to 5-year) time Risk/Benefit “Analysis periods. The consideration of uncertainty in planning or policymaking processes is a significant recent devel- Forecasting Water Use opment in water resources analysis. ‘‘Risk assess- Models for forecasting long-range water use ment, or ‘ ‘risk/benefit analysis, is required by range from simple extrapolations of past trends to the revised P&S for situations in which uncertain- complex models that project water use in response ty is an essential element of the planning process. to changing social, economic, and technological Risk/benefit analysis deals with uncertain events conditions. so as to reflect both the expected outcome (in a probabilistic sense) and public attitudes toward Simple models, often termed the ‘ ‘requirements uncertainty and risk. Public attitudes are particular- approach” to projection, have been favored by Fed- ly difficult to gage for those situations in which there eral agencies in the past. These models extrapolate are low probabilities of highly serious accidents. historical growth rates in water use, by use category or for total consumption. The models can be modi- Since the year-to-year and day-to-day variabili- fied to provide separate per capita use rates and ty of the hydrologic cycle encourages the presen- population projections, which are then combined tation of information in probabilistic terms, risk to produce a total water use projection. Under the analysis is a particularly suitable approach to water latter approach, per capita use is projected to grow resources decisionmaking. A flood or a drought or at historical rates and population projections are a pollutant spill of a particular magnitude will cause taken from separate demographic studies. The re- quantifiable losses. Estimates of the probability of quirements approach has been called into question that size flood or drought or spill occurring trans- because it has failed to project actual water use ac- form the projected loss to a statement of risk. Safety curately. The requirements approach also provides is generally paid for with time and money. Projects 160 . Use of Models for Water Resources Management, Planning, and Policy and policies, with their associated costs, work to These two factors mean that political decisions either reduce damages or the probability of an un- are likely to affect certain groups differently than desirable event. Judgments about acceptable levels others. Decisionmakers need to understand not only of risk and what should be spent to reduce them the effects of a project, but also what the effects will are a part of the politics of water resources. Models mean to the affected individuals. can help in clarifying those choices. Regional economic development models (de- Risk/benefit analysis organizes information so the scribed above) provide a basis for considering com- decisionmaker can compare the reduced risk of al- munity-level effects—particularly effects on hous- ternative policies with the increased costs. The ing, on the demand for public facilities and services, “benefit” side of risk/benefit analysis is generally and on the overall fiscal condition of local govern- a statement of net costs incurred by choosing a more ments. Once these consequences of a project have costly alternative over a less costly one. These costs been determined, consideration must be given to are calculated using estimation models similar to what the Water Resources Council has referred to those used for benefit/cost analyses. The ‘‘risk’ side as ‘‘social well-being. The remaining questions of risk/benefit analysis is a statement of the proba- are of two kinds: First, what is the effect of the proj- bility and consequences of a particular action or ect on the social structure of an area? Second, how occurrence. Consequently, risk/benefit analysis is are the economic, demographic, community, and not the sole domain of social scientists, but must social effects of the projects perceived by the affected rather be conducted by engineers, lawyers, and sci- people? Models and operational methods to answer entists from many disciplines. these questions are still in the research stage. Methods for estimating adverse health and safety Current research indicates that social structure risks are relatively new, but the cases in which these is definable in terms of: 1 ) the functional groups methods have been applied are relatively similar. in an area; 2) the characteristics of the groups (e. g., One of the major shortcomings of this approach is size, attitudes towards growth); and 3) patterns of the inadequacy of historical data to construct prob- economic, political, and social interaction among ability functions. Although subjective probabilities the groups (e. g., employee/employer relations and can be assigned by experts, such assignments can political alliances). Questions can then be asked: potentially impart biases to the analysis. The high Will a project introduce any new groups into an degree of uncertainty about dose-response relation- area? Will it in any important way affect the char- ships, in particular, tends to reduce the credibility acteristics of existing groups? Will it affect the way of quantitative estimates of risk. in which economic, political, or social interaction occurs among the groups? Answers to these questions constitute the social effects of a project in the Social Impact Analysis same sense that economic/demographic and com- The potential social impacts of water resources munity effects can be defined using the models and programs or projects have received increasing pub- procedures outlined above. lic attention in recent years. As a result, Federal The next step in social well-being analysis is to agencies have begun to develop accounting methods determine the significance of the changes to the peo- for social-effects that consider two important factors: ple affected. This requires that the distribution of 1. The effects of a program or project fall un- effects among the various groups be known and that evenly on different groups. For example, some their individual evaluations of these effects be deter- groups may benefit from increased employ- mined. Specifying the distribution of the effects ment, some may experience shifts in recrea- (economic, demographic, community, social) is tional opportunities, others may undergo tax usually possible once both effects and groups have increases. been clearly defined. Effects can then be evaluated, 2. The desirability of these effects will depend largely through direct questioning of group mem- on the value structures of the groups affected. bers or knowledgeable individuals. This part of the The impact of activities can be perceived dif- social assessment process constitutes ‘‘public in- ferently by different groups. volvement. Ch. 6—Modeling and Water Resource Issues ● 161

In projecting the social impacts of various The first models developed for unified river basin changes, models can be used to: 1 ) organize infor- planning were river basin simulation models com- mation on the social factors that are affected, and pleted during the 1960’s. These models linked water 2) qualitatively determine the direction of the im- resources to economic activity and demographic pacts (positive, negative, or no change). Even this trends. The Susquehanna River basin model devel- qualitative information can be useful to a decision- oped in the early 1960’s was the first of these ef- maker. If a systematic approach is not used, the forts, and demonstrated the applicability of a sys- inventory of social impacts may be incomplete. tems approach to river basin analysis. The general example provided by that work has been repeated Unified River Basin Planning and Management many times since. River basin models consider the simultaneous use Another related application of river basin analysis of water resources and the competing values associ- has occurred principally in the Western United ated with those uses. Such models are one means States. Models have been developed to analyze the of assessing the ‘‘value’ of water for alternative economic development implications of competitive uses—both for offstream purposes and recreational, demands for water among agriculture, energy-re- wildlife, and water quality instream uses. These lated mining or industrial development, and in rec- models form an analytical basis for examining alter- reational stream uses. Analysis of the implications native planning and management strategies for an of alternative allocation schemes has generally been entire river basin. River basin models require in- conducted at the river basin or State level, using put from a large number of disciplines as well as simulation models with hydrologic, econometric, information from economic and social models. and demographic components. Models of this kind were first developed for the purpose of analyzin Two principles are central to unified river basin g different resource management strategies in Utah planning and management: in the early 1970’s with the Utah Process Economic 1. River basin planning stresses comprehensive Demographic Model. Similar models now exist in analysis of the interrelationships among water many States and, among other applications, are resources and social and economic activity, used to analyze water resource management al- rather than the project-specific focus of most ternatives. planning activities. Only in a few basins have there been modeling 2. River basin planning emphasizes monitoring and data collection on the scale necessary to relate and analyses on a continuing basis, instead in detail both water quality and water demand to of only at times when specific projects are subregions and sectors. To do this comprehensively being considered. requires linking physical and social models that in- Since the methods applied in this area are similar clude many subjective inputs from citizens and/or to, or the same as, the methods discussed in the decisionmakers. previous sections, all of the justifications and limitations discussed in those instances apply here. Appendixes Appendix A Summary of Findings From OTA Workshops on Water Resource Modeling

During the fall of 1979, the Office of Technology Surface Water Quality Assessment held two series of workshops on water re- Participants in both workshop series placed high pri- source modeling. The first series, held on October 24 ority on two major research categories: 1 ) erosion and and 25, addressed issues raised by staff members from sedimentation; and 2) the fate and transport of toxicants. 21 Federal agencies. The second series, held on Novem- For the first category, Federal participants suggested ber 28 and 29, brought together 37 representatives of several specific areas requiring model development: universities and private consulting firms. ● Erosion models that predict the outcome of man- The two sets of workshops were identical in organiza- agement alternatives, such as deforestation. tion and operation. During the first day, both sets con- Models that determine the fate of chemicals before sidered problems in model development and applica- they reach the stream system. tion; on the second day, they considered problems in ● Physically based models for sediment detachment, model management and in the use of model results. Par- transport, and channel erosion. Empirically based ticipants in each workshop were divided into four topical models are currently being used. discussion groups: 1) surface water flow and supply; ● Sediment transport models linked with ecosystem 2) surface water quality; 3) ground water; and 4) eco- models. nomic and social factors. Each group, on each day it Participants agreed that improving the current state met, identified a list of problems that emerged during of knowledge about toxicants is urgently needed before the day’s discussion, and then used an idea-writing ses- better models can be developed to help in complement- sion to develop solutions to the problems identified. ing major regulatory programs. Federal participants em- This appendix synthesizes the results of the two sets phasized the need to improve understanding of: of workshops. Because many of the same problems were ● transport mechanisms; raised and discussed across topical groups and in both ● the long-term fate of toxic materials; and sets of workshops, results will be summarized by prob- ● the effects of toxics on biological organisms and lem area. Concerns or suggestions specific to one of the communities. series or to a topical group will be so identified. Federal personnel identified two further categories requiring research: reservoir and river mixing; and nonpoint source pollution. The group considered the first Research and Development (R&D)— topic a high priority because reservoirs and rivers are Specific Areas receptors of toxics, and because mixing is an important component of sediment transport. Participants in each of the four topical discussion Nonpoint source pollution was considered to be in- groups identified several specific research needs within creasingly important, as control of this problem becomes their assigned areas. These needs are summarized be- more cost effective than controlling point source pollut- low. ants. Specific model needs include: nonpoint source models that include toxics as wel] as sediment runoff; Surface Water Flow and Supply models to predict reductions in nonpoint source loadings due to various control strategies; Participants identified the following uses as research models that translate nonpoint source loadings into priorities: water quality and ecological impacts; and ● Online operations of water supply systems. Models models that qualify loadings under event-oriented need to be developed to aid managers in determin- conditions rather than on an annual basis.

ing current operating rules on the basis of present and historical flow and demand conditions. Ground Water ● Prediction of regional low flows and droughts. Models for stochastic analysis of regional hydrology Both series oi workshops advocated R&D of models need improvement. to analyze flow through aquifers that are difficult to

165 166 ● Use of Models for Water Resources Management, Planning, and Policy

characterize. The private sector group specifically iden- tion, and calculation. Knowledge of risks policy makers tified flow through fractured rock as a research need; would most like to avoid would also aid in designing one Federal participant gave the example of radioac- methods for reporting uncertainties. tive waste disposal assessment as an application in which Federal participants in the area of ground water mod- ground water flow is a highly important component. eling identified a need to improve parameter estimation Understanding the transport of chemicals through and methods for incorporating uncertainty into stochas- ground water in order to assess concentrations of con- tic models. They suggested: 1) that parameter estima- taminants was also identified as a research priority by tion procedures allow for interaction with the user to both workshop groups. Specific suggestions included: permit initial estimations, and to constrain the range . improving the numerical accuracy of ground water of values being generated; and 2) that uncertainty of transport models; input and its impact on reliability or confidence in out- . incorporating chemical reaction terms into trans- put always be considered during an analysis, to increase port models; and the utility and aid in the acceptance of ground water . researching the capability of aquifers to naturally models. cleanse themselves of pollutants. The private sector group unanimously suggested that the Government sponsor research at specific waste dis- Risk Characterization Methods posal sites. Members suggested that this research be part The surface water flow and supply group in the of a national program to deal systematically with pro- private sector placed high priority on two items: duction, processing, and disposal of potentially hazard- developing methods to characterize both long- and short- ous waste. term risk in water systems, including reservoirs; and conveying the concept of risk to the public. One par- Economic and Social ticipant noted that risk is relative, and asserted that modelers should therefore determine the cost of not Federal representatives considered interregional mi- meeting some requirements when judging risk and its croeconomics to be a research priority. Participants dis- impacts. Another participant argued that this approach agreed about both the adequacy of economic theory and would result in guessing with computer models, which the availability of data to describe interregional econom- he considered less reliable than experienced judgment. ic effects. Private sector modelers focused on intra- The Federal surface water flow and supply group fo- regional concerns; specifically, developing methods to cused on the relationships between extrapolation tech- analyze the distributional implications of water policies. niques and risk characterization. The group identified They pointed out problems of cost and availability for a need to improve techniques for extrapolating short- obtaining comparable data on a regional basis, and term simulation results for long-term implications. problems of determining the proper structure of mod- These extrapolation techniques are critical for extending els—e. g., the proper level of geographical aggregation, the use of available data bases. and assigning relative weights to social, economic, and environmental concerns when characterizing the effects of water resource activities. Predictive Capability

The surface water quality group from the Federal R&D—Methods workshop recognized a need to make ecosystem models predictive at higher trophic levels. Participants stated Two major themes emerged from workshop discus- that development of predictive models appears stalled, sions about modeling methods: 1 ) improving and char- even though the techniques are within the state of the acterizing predictive capability; and 2) integrating alter- art. Recently developed theory has not yet been incor- native methods and improving their ease of use. porated into predictive models. -The same group identified a need to improve predic- Methods to Measure Uncertainty tive capabilities and procedures for dealing with ‘ ‘non- predictive’ events. One participant suggested linking Participants in the private sector workshop stated that stochastic models with physical models to generate long research on quantifying the uncertainty of predictions time-series of simulated ‘ ‘data, which, along with is needed. Specifically, they suggested that improved, probability analysis, could help improve predictive capa- standardized methods need to be developed and adopted bilities, Probabilistic models could also be coupled with for assessing the total uncertainty in model outputs due or used as complements to parametric and deterministic to errors in data, sampling, model parameter estima- models. App. A—Summary of Findings From OTA Workshops on Water Resource Modeling ● 167

The surface water quality group was also concerned bers already specified for comparative and reporting over the need to improve current capabilities to model purposes. transient effects.

Model Integration and Coordination Data

In the private sector workshops, both the surface One of the major concerns of both Federal and private water quality and economic/social groups focused on the participants was that data are not available to develop, need to interrelate different types of modeling capacities. calibrate, validate, and apply models. Federal modelers Participants in the surface water quality group stated identified the intensive data needs of complex models, that research should be done on methods to improve the cost of data collection, and the lack of coordination compatibility of components of water quality models. and planning of data gathering as major reasons for the The major components of these models—sources of ma- unavailability of data. terials, transport to and within receiving waters, and Private participants tended to agree that the data- processes occurring within receiving waters—are mod- gathering process should be related more directly to the eled individually and independently, often at different needs of models. Some suggested that modeling should times and space scales. Research is needed to make the precede and guide data gathering. Federal participants individual components compatible over the longer time stressed the need for model developers to be more sensi- and larger space scales needed for effective water quality tive to the potential data requirements and data costs models. of their models, and suggested that data collection occur Private sector economic/social modelers suggested the concurrently with model development. need for methods to integrate their work with physically Federal participants also agreed that improved data- based models. collection techniques are needed to facilitate more eco- nomical data acquisition. Some participants expressed Higher Dimension Models a need for greater attention to the design of data networks. Private modelers felt that the problem of inade- The need for two- and three-dimensional models for quate data often arises because Congress and govern- rivers and other water bodies was mentioned by the sur- mental agencies are unwilling to conduct data collec- face water quality group. One view was that for plan- tion and review programs. Participants noted that many ning or screening alternatives, one-dimensional models model types continue to be developed without adequate are often, though not always, sufficient. For design pur- data to support them. They felt that certain model types poses, two- or three-dimensional models are frequently should not be developed without commitments to related important. data-gathering activities. However, private sector par- Participants suggested developing a research program ticipants noted that if data collection is not funded, reg- to determine the type of models needed for different ulations will need to be designed to accept qualitative types of problems—relating the dimensionality of the or semiqualitative solutions. models to different water bodies and pollutants. To improve data availability, Federal participants suggested that developers, users, and data gatherers Methods To Improve Model Use should: 1) share data and identify cooperative data needs; 2) perform sensitivity analyses to identify the Workshop participants suggested several R&D areas most critical data needs; and 3) develop mechanisms to that might result in more efficient and productive uses identify and collect long-term data. They also stressed of models. These include: that continual reprogramming of research funds often . using models that address a wider range of aherna- causes long-term data needs to be neglected. tives— this is of primary importance in economic models; developing more efficient analytical methods to re- Existing Data Bases veal sensitivity relationships to the user; and developing improved model calibration methods, Federal participants felt that it would be cost effec- including automated and user-interactive methods. tive to spend additional time analyzing existing data Finally, members of the private sector surface water bases. The surface water flow and supply group sug- flow and supply group suggested that standard, accepted gested that better agency coordination is needed to con- models for routine tasks be identified and made avail- solidate existing data bases. The group recommended able. In addition, they advised that standard computer that data base management specialists be employed to programs be designed that include a set of random num- manage agency and interagency data systems. 168 Use of Models for Water Resources Management, Planning, and Policy

National Data Bank failure to model phenomena that are not well enough understood to be modeled); case studies and examples The private sector group held extensive discussions representing previous successes and failures; references on the need for a national data bank. Speaking against to literature citations and names of people and organiza- the idea, participants stated that data banks in general tions who have used the model; operation costs; person- are not desirable because data collection should be done nel requirements; and a program listing and computer with specific model formulation in mind. People in the requirements. ground water group wanted a standard data base developed for independent model comparisons. Suggestions for groups to manage a data bank included the Environ- Validation/Credibility mental Protection Agency (EPA) laboratory at Ada, Okla., or the Holcomb Research Institute, with funding Federal participants identified the lack of model vali- by EPA. Some people in the surface water group wanted dation as one of the most important problems in water a national data base to supply consistent, experimental resource modeling, and discussed three major factors data for establishing the interrelationships between contributing to the problem. quantity and quality parameters. In the economic/social First, resources are not adequately allocated for model group, some members felt that an agency similar to the validation because of its high costs. These costs might Census Bureau should be established to obtain reliable be reduced if interagency cooperation increased (e. g., and consistent water resource data. cooperative interagency sampling and funding arrangements). Documentation Second, the lack of necessary data for validation requires attention. The cost of data collection, the absence Federal and private sector modelers strongly believed of historic data, and the time necessary to collect valida- that inadequate documentation restricts the wide use of tion data are all limiting factors. good models and contributes to the misuse of models. The third factor was the absence of guidelines for val- Participants agreed that the inadequate allocation of idation, identified specifically by the surface water flow resources for documentation and the lack of incentives and supply group. A majority of the group supported to promote good documentation greatly contribute to guidelines, while recognizing that guidelines would be the problem. difficult to establish because of the diversity of model Federal participants suggested the following remedies: designs and applications. A lead agency might be given responsibility for suggesting appropriate guidelines. ● Assign responsibility for documentation to an organizational unit to ensure that adequate resources The private sector groups advocated establishing ap- are allocated. This unit might also handle technol- propriate incentives for validation. Other suggestions ogy transfer, users’ assistance, etc. from the private sector focused on specific procedures for model validation, requiring sensitivity analyses on ● Provide incentives to modelers to allocate time to documentation efforts. all analyses made, and requiring followup investigation where model scenarios have been implemented. ● Establish minimum guidelines for documentation. Private sector participants tended to advocate more Participants from the private sector also felt that mod- prescriptive approaches. They asserted that agencies els should be subject to peer review. They suggested that should demand acceptable model documentation of all agencies contract for intensive review in key project models developed with public funds. As an added incen- stages, such as definition, completion of model develop- tive, agencies might withhold a percentage of the proj- ment, and review of results. ect costs until adequate documentation is received. Cur- rently, they complained, Federal agencies such as the Technology Transfer and Training Office of Water Research and Technology and the Na- tional Science Foundation may end funding before the The majority of participants in the Federal workshop documentation project is complete. considered improving technology transfer to be a top Federal participants specified two separate compo- priority; private sector participants agreed that appro- nents for adequate documentation: 1) a technical docu- priate technology transfer and Federal agency policies ment; and 2) a users’ document. A separate programmers’ on technology transfer do not currently exist. document and an executive summary document were While most Federal participants believed that respon- suggested by a few participants. In the private sector sibility for technology transfer lies with the model devel- groups, suggested components for complete documenta- oper, they also recognized that agencies need to pro- tion of a model included: user’s manual; capabilities and vide adequate resources for technology transfer pro- limitations (including explicit acknowledgments of the grams. They suggested that proper allocation of re- App. A—Summary of Findings From OTA Workshops on Water Resource Modeling “ 169

sources might be expedited if responsibility for technol- Federal participants proposed several specific methods ogy transfer were given to a lead agency. Modelers from to improve model maintenance: the private sector suggested that for agencies currently establish minimum guidelines and standards for without technology transfer mechanisms, either in-house model maintenance; development or outside contracting would be appropri- prepare a written plan for long-term maintenance ate. and assurance of adequate resources to undertake Private sector participants tended to focus on train- such maintenance. Year-by-year requests are in- ing in specific disciplines and related model use as an appropriate; important component of technology transfer. Partici- assign responsibility for model maintenance to an pants mentioned the federally supported university organizational unit and assure that appropriate re- training grant programs in environmental pollution and sources are available to carry out this goal. This environmental health (now discontinued)—a compar- group might also be responsible for model docu- able training program in water resources is needed mentation, user assistance, and technology trans- today. They felt that funding universities to transfer new fer; and developments to the agencies should continue. establish an interagency clearinghouse to conduct Participants from Federal agencies made a number a periodic survey of models, and to update and/or of suggestions regarding particular methods of accom- revise model components as needed. plishing technology transfer. Most agreed that the most important mechanism is one-to-one interaction between Clearinghouse the user and the developer. For example, developers might be temporarily assigned to a user’s organization Perhaps the most controversial of the subjects ad- to assist the user, and in addition, provide feedback for dressed at the workshop series was the concept of a clear- the developer. Using a central technical support staff inghouse for information on available models. Most par- to help solve operational problems was also suggested. ticipants in the private sector agreed on the utility of Workshops that give participants “hands on” interac- some form of a model clearinghouse; Federal modelers tion with models, and seminars, were considered good in the surface water quality and surface water flow and transfer techniques, especially if the developer is directly supply groups classified the concept as one of their 15 involved. Workshops and seminars designed for differ- priority categories. The latter groups stated that a clear- ent levels of users (e. g., managers, technical specialists, inghouse or inventory is needed to aid technology trans- modelers, and laymen) were also deemed necessary. fer and to serve as an information source for effective Generally, Federal participants believed that agen- planning for future model development. cies need to develop incentives for developers to invest In the Federal workshop, the clearinghouse concept time in technology transfer activities. Many acknowl- was conceived as having various possible levels of opera- edged that current agency career evaluation systems tion. At the simplest level, a periodic inventory might discourage modelers from providing adequate technol- be established—e. g., a central catalog of models by sub- ogy transfer. ject area, listing available models, the agencies that use the model, and a contact person or agency. While such Model Maintenance an inventory might be adequate, it would likely be difficult to administer. Both Federal and private workshop participants A fully established clearinghouse could offer several strongly believed that adequate model maintenance is extra services. The participants felt that responsibility essential for effective model use. Private sector partic- for the clearinghouse should be assigned to either an in- ipants specified that Federal funding should be provided teragency group or a particular agency. The clearing- to support model maintenance and updating, but dif- house could assist future model development by acting fered in their views on appropriate institutional arrange- as a focal point for the questions of both developers and ments to provide such support. Proposals included: users. It could help to isolate needs for cooperative stud- ● designating a lead agency to track and disseminate ies and determine areas of duplication. Federal model information and revisions; Some Federal participants felt that technical litera- ● requiring the sponsoring agency itself to maintain ture, conferences, and professional meetings could ade- and update the model; and quately serve the same function. Other participants ● having the agency provide funds to the developer strongly believed that these mechanisms were not suffi- (or other outside group) to maintain and update cient, partly because some operational agencies seldom models. publish their modeling efforts. Additional skepticism was 170 . Use of Models for Water Resources Management, Planning, and Policy

expressed about the cost effectiveness of the clearing- and distrust of good models. User understanding was house approach. considered especially important for economic models, Private sector modelers who opposed the idea asserted because they cannot be easily validated. In this case, that it might cause centralization, resulting in red tape, it would be very important for the user to understand regulation and ineffective action; and siphon limited model construction in order to have confidence in the funding that could be better spent elsewhere. model. Workshop participants felt that managers/decision- Coordination makers must be provided with the following information: Participants in both sets of workshops concurred on ● the underlying conceptual basis of models (rather the lack of coordination of resources and information than detailed mathematics); for model development among Government agencies. ● a taxonomy of resource models matched to a cor- Private sector participants, while dismissing the issue responding taxonomy of resource problems; of duplication as a minor problem, proposed better re- ● the relative uncertainty of different models’ results; gional and interagency cooperation to improve coordi- and nation. Federal modelers noted the lack of mechanisms ● alternative ways to use models to solve ‘‘ real- to promote interagency efforts, and the absence of incen- world’ problems. tives or precedents for agencies to work together. Federal participants suggested a number of mecha- Responsive Model Selection nisms for improving interagency coordination: and Development ● a national clearinghouse and periodically published information directory to provide users with Federal and private sector modelers concurred in con- information about the quality, availability, and sidering the selection and development of inappropriate characteristics of models; models a major problem, and in the need for modelers ● an interagency model development review commit- to pay greatest attention to policymakers’ needs and ob- tee. This responsibility might be assigned to an ex- jectives in selecting/developing appropriate models. One isting committee. Some participants felt that the participant estimated that 75 percent of all models are committee should have only an advisory role, fear- created without a suitable set of specifications defined ing infringement on agency and scientific freedom; by the problems toward which they are directed. Federal and participants further emphasized the need for users to ● a centralized source of expertise to advise on inter- understand their own needs and the limitations and agency data base creation. assumptions of the models they consider. Questions arose as to the practical value of some of Users often want quantitative answers to specific the suggested mechanisms in view of the diversity of management questions and issues. However, according agency needs. Coordinating efforts through interagen- to Federal participants, the users may be unsure of what cy meetings were considered to be too broadly philo- information is necessary or may perceive that models sophical to aid with actual development. However, par- have greater capabilities than they actually do. In gen- ticipants recognized the importance of avoiding new eral, good documentation can help users understand model development when an existing model can be mod- model capabilities. The participants suggested several ified to serve the same purpose. specific mechanisms to help users gain a better understanding of what models exist and how these models can Educating Managers and be used to solve specific problems: Decisionmakers ● Summary documents listing models available in each agency. These documents would briefly de- The need to educate management and decisionmakers scribe operational and developmental models and to the capabilities, assumptions, and limitations of mod- their assumptions, capabilities, limitations, appro- els was stressed by participants in both workshop series. priateness for specific applications, and the devel- Private participants emphasized the importance of dem- opers’ names and phone numbers. These docu- onstrating to managers/decisionmakers that models are ments could stress the specific questions that avail- simply tools that provide information and insight, rather able models can address. than solutions. Federal modelers were concerned about ● Seminars for users in each agency on state-of-the- the loss of credibility suffered by models as a result of art modeling efforts. poor user understanding. They noted that users’ lack A final recommendation from private sector modelers of understanding of key concepts leads to model misuse was that repeated interaction between modelers and pol- App. A—Summary of Findings From OTA Workshops on Water Resource Modeling ● 171

icymakers is necessary to respond to new objectives and that agency contracts be more specific concerning the problems suggested by model results. Federal partici- legal liability of the model developer. pants suggested a number of specific mechanisms for Conflict among Federal, State, and local decisions accomplishing these interactions. To develop general- based on the use of different models was also considered. purpose models, the participants recommended using Communication and cooperation among agencies, in- modern group management techniques to solicit the cluding joint model development, was suggested to alle- needs of potential users. For more specific models, im- viate these problems. However, participants also noted proved communication between users and developers that different and conflicting laws, delegations of author- was considered necessary. Several participants suggested ity, and organizational interpretation of laws and models predevelopment working sessions to help modelers de- contribute to interjurisdictional disputes. termine users’ needs and help the users understand what Participants from the private sector emphasized that models can provide. regulations should not require specific methods. Many thought that models used in regulatory applications Legal and Regulatory Problems should stress objectives, not specific methods. Others thought that models used in regulatory applications Problems mentioned by conference participants from should be required to undergo peer review and valida- the private sector in this category ranged from legal lia- tion. Another suggestion was to establish a continuously bilities associated with the use of models to interjurisdic- reviewed listing of models appropriate for certain regu- tional disputes over model use. Participants suggested latory applications. Appendix B Summary of Model Use by Individual Federal Agencies

Introduction Conservation Act); and the Water Resources Planning Act (Public Law 89-80). It uses models in each program This appendix summarizes water resource modelingarea. activities of Federal agencies, using information supplied Under section 201 of the Clean Water Act, which by the agencies and reviewed by OTA contractors and deals with construction grants for treatment plants, ESS staff. The information was obtained from three sources: has used models to assist local groups in Pennsylvania participants attending an OTA workshop, selected in- in choosing among alternatives for treatment facilities. terviews with agency personnel, and a survey requesting ESS also uses these models as part of its own general agencies to indicate their model use under specific water research and development effort. For its programs in resource laws. Agency representatives to the OTA work- areawide waste treatment management planning, under shop on Federal agency model use provided OTA with section 208 of the act, ESS has developed a large policy a written description of their agency’s model use and model to evaluate alternatives for improving water qual- model documentation, when available. Further informa- ity in the San Joaquin Valley in California. Among the tion about model use and model documentation was ob- factors the model considers are land-use options, zon- tained through selected interviews with agency person- ing, and application of irrigation water. ESS uses models nel. The survey yielded information on legislation- under section 209 of the act as well, which addresses related model use in Federal agencies as of June 1980, nationwide river basin planning. Models are also used for agencies and ofllces in existence at that time (see sur- to determine the minimum cost of comporting sewage vey form, attachment II). sludge in evaluating different projects under section 405 This appendix describes, by agency, the water re- (disposal of sewage sludge) of the Clean Water Act. source programs in which models are used and the types ESS is also involved with regional or river basin plan- of models generally employed. The summary table of ning under section 102 of the Water Resources Plan- agency model use (table B-1 ) provides an overview of ning Act. The service uses models to estimate economic the water resource modeling activities of most of the impacts of section 102 programs (regional or river basin agencies discussed in the text. The 33 water resource plans). The models help project future economic condi- issues used to construct the table are listed in their unab- tions in rural areas under various scenarios. As is the breviated form in table 1 of chapter 2. References for case with all USDA river basin studies, these studies the text are listed by agency in attachment 1. are carried with the cooperation of local sponsors. In planning conservation programs under section 6 U.S. Department of of the Resource Conservation Act, ESS uses models to Agriculture (USDA) project the likely effects of different economic conditions and conservation programs on land and water use, on Economics and Statistics Service (ESS) erosion, and on the national economy. ESS develops and applies computer programs for such ESS provides economic projections of short-term and other agencies as the Soil Conservation Service, the Wa- long-range agricultural demands for land and water re- ter Resources Council, and the Environmental Protec- sources. Its analyses focus on how alternative develop- tion Agency (EPA). These models generally incorporate ment of such resources could affect the agricultural and economic criteria and are often of the optimizing or related sectors of the economy. ESS responsibilities in- prescriptive type. An increasingly important service of clude basinwide and interregional economic aspects of ESS is to maintain the Land and Water Resources and comprehensive river basin planning. Economic Modeling System (LAWREMS) described in ESS is involved in programs under the Federal Water chapter 4 of this report. This directory aids commu- Pollution Control Act of 1972 (Public Law 92-500), as nication and technology transfer among agencies in amended by the Clean Water Act of 1977 (Public Law order to reduce duplication in model development. 95-217, hereinafter referred to as the Clean Water Act); LAWREMS contains models and data sets developed the Soil and Water Resources Conservation Act (Public and maintained by ESS and other agencies and non- Law 95-192, hereinafter referred to as the Resource governmental bodies.

172 App. B—Summary of Model Use by Individual Federal Agencies ● 173 To. A X .l\. LI.. x WRC X X X X A X -- X EPA x X LI.. -- X X CEQ x X X X -- X X LI.. .l\. LI.. I\. USGS G y of Y X X I\. A A LI.. To. X A X X I\. x Bureau Reclamation 1981 A X X X Il.. I\. X X FWS Y X X A A- I\. X X LI.. To. X January DOE - y of Use Y X x A A To. X X X X X To. x X x x Emdneers Corps Model y To. Y To. X A X x Agency Service National Weather WY X X LI.. I\. LI.. x X u x x

m S S Federal y y - To. X X Y Y A SEA B-1 y X To. X X Table Sprvic~ Forest X X Y Y X V X X X X LI.. ESS --, fp I:V Q li --_. f control R rnr~("'.::tR.r ~,"_a t1gm.anrlc:. nll::ll' conservat10n ..... ru ".111 nPM po __ anal~sis rl1nnf ::Ina..1.VQl ; 111~!:In""C! po ... .,ag uClA ma------~lntJ .... f allocation AnIlAt:iC'. nw and reQ:ulat10n ftlT supp~y 1 o,.'=n',"nn l1RP rllT w;:!rPT UQ nnl Qllnnlv f nollutlon 1 -I",o --_... nn < g 1moacts ... r t"l1r.,l ---~- 8I nl7 load TlInnf rna <- rv>nprll: ot me n _ rrnt-.o.A 1',,1 m nK' t-rp;:!m a_n,r,+-.f nld ..... rRrrp;:!m ...... -_. .,..hnY'"no gr omn~r-1 ... ,..,...; nQ -F,..,. SOCl.al benefit/cost r.l.HK.1 imnAC'.t:A ava~~aD~e nT' "'l"\n""1;1"", !!I cost _1 r H~LV ;:!O'ri ettlclenc~ nr '" i IlTM streamLlow i1nmgcr-1r- waste rtrnl1aht"JlntJ resource I I Q:c:.l1~C: I" of 0 wl·rno.nn p a u a u 8 ~ :l ~ p..-; ~ P 0 UJ ~ :l Q) 0."-; ~ ~ t.] o::s I-< 0 -,-I +J M 0' za... ::J 0' 0' r-; !:Ij I~ r-; '0 ,-.-i 1-'< ~r-; C.J cU-,-I I-Ir- ~,~ tJ'i+J .-i :>, .j.J+J Water ~ ~ ~ 0 Ul .j.J T • ~ .--i .--i "I o u o p 8 w ~ ~ C1l Q) 1-1 C1l " ~ ~ U ~ C1l Q) .j.J r.Il ~ r.Il a3P3zns~ I I 174 ● Use of Models for Water Resources Management, Planning, and Policy

Forest Service and to project the economic effects of such management practices on localities. Models also aid in determining The Forest Service is responsible for developing, man- National Forest Management Act regulations—the aging, and protecting lands in the national forest system. models are used to analyze potential standards and Its objectives include fostering multiple use and sus- guidelines and compare results of their applications. tained yield of forest and rangeland resources. Beyond Under planning activities mandated by the Forest and its research and data-gathering functions, the Forest Rangeland Renewable Resources Act of 1978, the For- Service coordinates planning for the forest~ component est Service uses models to compute soil moisture and of river basin surveys and investigations, as well as for streamflow in forests and rangelands. Information on the small watersheds program under the Watershed Pro- soil moisture is used to determine whether and when tection and Flood Prevention Act (Public Law 83-566). to plant trees, and to determine viable levels of livestock It is also responsible for managing flood plains and proper acre of rangelands. The effects of timber harvesting tecting wetlands on national forest system lands. on streamflow are evaluated using water yield models, The Forest Service carries out a large number of pro- which determine the maximum levels of harvest consist- grams authorized under water-related legislation, and ent with preventing excessive peak flows in rivers. Mod- uses models in connection with many of these programs. els are also used to determine harvest designs which in- These include: crease the water yield in watershed areas. Under the Clean Water Act: ● section 107—mine-water pollution control; Science and Education Administration (SEA) . section 208—areawide waste treatment; ● section 209—river basin planning; SEA is actively involved in water resources model- . section 303—water quality standards and imple- ing as part of its mission in natural resources research. mentation plans; and The agency’s water resource modeling activities em- . section 3 14—clean lakeso brace a wide range of topics: climate and weather, the Under the Endangered Species Act (Public Law hydraulics of overland and channel flows, rill and in- 93-205): terrill erosion, sediment yields from agricultural water- ● section 7—minimizing impacts of Federal activities sheds, infiltration, evapotranspiration, irrigation sched- modifying critical habitats. uling, subsurface drainage, and the transport of agri- Under the Surface Mining Control and Reclamation cultural chemicals, among other topics. Act (Public Law 95-87): In its program under section 208 of the Clean Water . section 506—surface coal mine reclamation per- Act, SEA uses models to estimate the effects of land- mits; and use practices on agricultural nonpoint source pollution. ● section 51 5—environmental protection perform- This information is made available to USDA ofilces and ance standards for surface coal mine reclamation. to the public through USDA technical assistance pro- Under the Resource Conservation Act: grams. The agency also uses water resource models in ● section 5 —collection of data about soil, water, and the agricultural research it conducts under section 1402 related resources; and of the Food and Agriculture Act of 1977 (Public Law . section 6—soil and water conservation programs. 95-1 13). Models are used to predict the effects of differ- Under Executive Order No. 11988: ent land-use practices on agricultural and nonpoint . sections 5 and 6—flood plain management. source pollution. Under the Water Resources Development Act of 1974 SEA extramural funds are used for scientific research (Public Law 93-251): at universities to assist in developing water resource ● section 73—planning nonstructural measures. models for resolving local, State, and regional water and Under the Flood Control Act of 1936 and amend- water-related problems. The research may produce ments (33 U.S. C. 701, et. seq.): components and mathematical techniques for use in de- . sections 1 -3—choosing and designing flood control veloping models or in checking the scientific validity of structures. models. SEA scientists coordinate these research efforts The Forest Service provided detailed information on among the respective States and the intramural research models used under the Forest and Rangeland Renew- programs of SEA. In a number of cases, State and Fed- able Resources Planning Act of 1974, as amended (Pub- eral scientists are cooperating on the same regional proj- lic Law 93-378). Under this act the Forest Service cre- ect, working on mutually developed objectives, and ates and implements long-range land and research man- sharing ongoing research progress at least annually. agement plans at local, regional, and national levels. For the most part, SEA’s modeling program aims to Models are used to estimate changes in water quality improve understanding of the fundamental physical, and supply under alternative management practices, chemical, and biological processes that control or con- App. B—Summary of Model Use by Individual Federal Agencies . 175

strain crop production; assist resource conservation; and type is a System of Watershed Automated Management reduce present or future impacts of agricultural activities Information (SWAMI), used to evaluate present pro- on the environment. In selected areas such as erosion grams and assess needed changes. and nonpoint source pollution, model development has SCS river basin and area planning activities use mod- reached the point that applying the models to resource els for planning and evaluating the physical, environ- management, planning, and policymaking is considered mental, and economic aspects of water resources. Most both feasible and justified. Examples of these models activities include an inventory of existing resources, are the Universal Soil Loss Equation (USLE) model, projections of future resource uses, and the evaluation and the Chemicals, Runoff, and Erosion from Agricul- of alternatives. Some studies develop specific models to tural Management System (CREAMS) model. represent unique physical processes where no existing model can be used. Soil Conservation Service (SCS) Other programs involving model use that are authorized under water-related legislation include: SCS is authorized to develop and carry out a national ● The Rural Clean Water Program (Public Law soil and water conservation program in cooperation with 96-108), which uses models to evaluate the quality landowners and operators and local, State, and Federal and quantity of runoff from agricultural watersheds agencies. Its programs assist farmers, ranchers, and and to evaluate alternative systems of best man- State and local organizations to prepare plans for re- agement practices. source management, including structural and nonstruc- ● The Resource Conservation Act (Public Law tural improvement for flood protection, water conser- 95-192), under which models are used to predict vation, use and disposal of water, agricultural pollution the effects of conservation programs on erosion control, environmental improvement, and rural com- rates and land and water use. munity development. ● The Clean Water Act (Public Law 95-217; sec. SCS has a background of mathematical modeling dat- 208j), under which models are used to determine ing back to the 1950’s. It has applied models to flood the effects of conservation practices on nonpoint and irrigation water control and to erosion and sedimen- source pollution from agricultural land. tation problems. The principal physical models deal ● The Colorado River Basin Salinity Act (Public Law largely with hydrologic phenomena: generation of hy- 93-320), under which models are used to determine drography; flood routing; calculation of areas, eleva- the effects of irrigation practices in specific areas tions, and frequencies of floods; and the mechanics of on salinity levels in the Colorado River Basin. irrigation. One model is devoted entirely to applications ● The Flood Control Act of 1950 (Public Law of the universal soil loss equation, although this function- 81-516), under which models are used to select and al relationship also appears in many other models. design floodwater-retarding structures built under Recently, several models for economic evaluation this authority. have been developed. In fact, approximately one-half ● Floodplain Management (Executive Order No. of the 30 models SCS currently uses are physical/eco- 11988), under which models are used to delineate nomic integrative models that serve as planning tools flood plains and to predict the river stage effects to help evaluate and select conservation strategies. They of different levels of flood plain encroachment. are used, for example, to project floodwater damage to urban and agricultural areas, and the costs and benefits Department of Commerce of various cropping, conservation, and land-treatment methods. National Oceanographic and Atmospheric SCS reported model use under a number of legislative Administration (NOAA) mandates. Under the Rural Development Act of 1972 (Public Law 92-419), the agency uses models to assist NOAA uses models extensively to support its numer- qualified local sponsors in initiating and sponsoring re- ous activities under current water resource legislation. source conservation and development areas. Under the Clean Water Act, for example, NOAA’s ac-

Through the Watershed Protection and Flood Preven- tivities in basin planning, secondary treatment re- tion Act (Public Law 83-566), SCS has primary respon- quirements, water qualty standards, standards for sibility for USDA’s cooperation with local organizations pretreatment of toxic effluents, and clean lakes (sees. in small watersheds throughout the Nation, and has spe- 219, 301, 313, 307, and 314, respectively) all involve cific responsibility for flood prevention measures. To some model use. NOAA also uses models in its soil and carry out these responsibilities, two types of models are water programs under the Resource Conservation Act used—a management information model and models to and in its programs under the Water Resources Plan- determine the effects of water quality projects. The first ning Act. 176 ● Use of Models for Water Resources Management, Planning, and Policy

Information from NOAA models is also supplied to Department of Defense Federal agencies concerned with fish and wildlife habitat protection under the Fish and Wildlife Coordination Act U.S. Army Corps of Engineers (16 U.S.C. 661). These models help project effects on fish and wildlife habitats when planning or evaluating The Corps of Engineers is authorized to investigate, projects. NOAA also uses models under sections 101 develop, conserve, and improve the Nation’s water and and 102 of the National Environmental Policy Act water-related land resources. Its programs include plan- (Public Law 91-190). Models are used to estimate ef- ning and development activities for protecting navigable fects on instream flow, evaluate effects on habitats and waters, flood control, hydroelectric power production, on an ecosystem’s trophic relationships, and predict the flood damage reduction, flood hazard information, probable dispersion of an oil spill. urban land drainage, wastewater management, shore NOAA’s hydrologic service programs are managed and beach restoration and protection, fish and wildlife by the National Weather Service (NWS) under author- conservation, outdoor recreation, aquatic weed control, ity of its Organic Act ( 1890) and the Flood Control Act and environmental protection. These responsibilities in- of 1936($ 1,2,3j, 15 U.S. C. 313, 33 U.S. C. 706). NWS clude consideration of the economic, social, and en- is responsible for issuing weather and river forecasts and vironmental impacts of public works alternatives. warnings. Federal, State, and local agencies rely heavily The Corps’ mandates are based on a wide variety of on NWS for river and flood information for manage- water-related legislation and many are carried out with ment planning, and for probable maximum precipita- the use of models. Under the Clean Water Act, the tion estimates used in designing river and flood control Corps uses models to help evaluate costs and designs structures. NWS hydrologic forecasts are important for for water treatment facilities proposed for Federal fund- reservoir operations, water supply management, naviga- ing pursuant to section 201 of that act. The Corps also tion, irrigation, power production, recreation, and water uses models under section 1444 of the act (Federal facil- quality management. Most of the information supplied ity pollution control). is output from models. The Corps employs models in its water resource plan- The agency’s concentrated ongoing effort to imple- ning activities. It uses models in its regional or river ment a system of interrelated mathematical models and basin activities under section 102 of the Water Resources predictive techniques is known as the National Weather Planning Act (Public Law 89-80) and in planning and Service River Forecast System (NWSRFS). The system evaluating nonstructural measures under section 73 of incorporates models already in use and new hydrologic the Water Resources Development Act (Public Law forecast techniques. Included are models of snow accu- 93-251). mulation and ablation, soil moisture, streamflow rout- The Corps makes major use of models in connection ing, and unsteady open channel flow. The system also with its flood control and management function. Models includes programs for handling and processing data and are used in designing and selecting flood control struc- for model calibration and verification. Planned additions tures to be built pursuant to the Flood Control Act and to NWSRFS are an enhanced reservoir operation mod- in planning or evaluating flood-control projects. The el, and an extended streamflow prediction technique for models help assess flood peaks, compute water surface water supply forecasting based on a conceptual water- profiles, and supply data for flood damage assessment. shed model. The extended streamflow prediction tech- The Corps also uses models to assist the Federal Insur- nique will eventually complement the current water sup- ance Administration in conducting flood insurance stud- ply forecasting procedures, which are based on statistical ies under the Flood Control Act. methods. The Corps’ flood plain management programs under The first version of NWSRFS was implemented in Executive Order No. 11988 also make use of models. 1971 and used for river forecasting in the lower Missis- Models are used to delineate the 100-year flood plain sippi River basin. When fully implemented, NWSRFS so that Federal and non-Federal interests may comply will be used by all 13 NWS River Forecast Centers with current regulations. For example, one regulation (RFCS) in preparing daily streamflow forecasts for more requires that flood plain encroachment should not result than 2,500 river forecast points and drainage areas cov- in an increase in water surface elevation of more than ering approximately 97 percent of the United States. 1 ft. The models help predict the relationship between App. B—Summary of Model Use by Individual Federal Agencies ● 177 extents of encroachment and the rise in surface water Department of Energy (DOE) surface elevation. The Corps’ research and development in water re- Office of Environmental Assessments source modeling focuses on solving field problems. In hydrologic analysis, the Corps’ Hydrologic Engineer- Within the water resources area, DOE’s OffIce of En- ing Center (HEC) has developed a number of computer vironmental Assessments is concerned with the impacts models for evaluating the expected magnitude and fre- of energy technologies on water resources, including the quency of runoff from urban and nonurban watersheds. effects of energy-related pollutants on biological systems. The principal urban runoff models are HEC-1 and The office is also involved in defining water and land STORM. HEC models have also been used to improve resource requirements for energy technologies including the operation of reservoirs during floods. Both HEC and coal gasification, coal liquefaction, uranium enrichment, the Corps’ Waterways Experiment Station (WES) have geothermal development, small-scale hydroelectric de- developed several models relating to river mechanics. velopment, enhanced oil recovery, and shale oil produc- These models simulate hydrodynamic and sediment tion. transport processes in rivers, lakes, and estuaries. The The majority of the water resource models DOE uses Corps’ WES and the Coastal Engineering Research are deterministic simulations of physical systems, and Center (CERC) have also developed and applied various they deal primarily with three subjects: assessing sur- models to compute hurricane surges and wave heights face water supply related to the potential for energy for design and planning purposes. facilities development; analyzing energy-related envi- HEC has developed two reservoir-system analysis ronmental impacts including thermal effects and trans- models: HEC-3 and HEC-5. These are multipurpose port of various pollutants; and determining the econom- reservoir operation models used in planning and oper- ic and social effects of water use for energy development, ating reservoir systems for flood control, hydropower, The Ofllce of Environmental Assessments uses several and water supply. The models have been used at the water resource models. The Water Assessment System planning level to evaluate the water-supply performance (WAS), located at Oak Ridge National Laboratory, is and hydropower potential of existing and proposed res- used principally for large-scale regional impact assess- ervoirs, and to study flood control. The HEC-5 model ments. This model projects variations in streamflow, is currently being used in operational studies of hydro- water use, and water availability over time to assess power sites selected from the Phase I screening of the water availability for various energy scenarios. The basic National Hydropower Survey. The Corps also uses geographic unit is the Water Resources Council (WRC) models to assess the potential impact of a partial or com- aggregated subregion (ASR) level. In support of plete dam failure. WAS, the Automated Downstream Accounting Model Both HEC and WES are developing water quality (ADAM) calculates cumulative water availability and models. These models are applied to proposed Corps consumption data for surface streams in hydrologic projects to predict overall water quality conditions and sequence. to develop appropriate design and operational criteria The Water Use Information System (WUIS) of Han- for attaining desired water quality levels. Models are ford Energy Development Laboratory is used for a num- also used to evaluate design of operational modifications ber of DOE assessments. This is a computerized infor- for projects in which water quality problems exist. mation system containing comprehensive data on water The Corps’ water resource planning models focus on resources, on water availability and quality, and on elec- flood control. Flood-damage computation procedures trical generating plant characteristics and operational are part of several of HEC flood forecast and control characteristics relating to water use. Its basic geographic models. These procedures evaluate the expected damage resolution is the WRC cataloging unit. The Los Alamos from a series of flood events, with and without various Coal Use Modeling System (LACUMS) incorporates proposed management measures. An optimization rou- water supply and demand sectors into a linear program- tine in the HEC-1 model analyzes various sizes and ing model of energy supply to facilitate water- and

combinations of flood-control measures and allows for energy-related policy analysis. Water S UPPIY is ac- the evaluation of tradeoffs among facilities, perform- counted for by coal demand regions. ance, and cost. The HEC interactive nonstructural anal- For large-scale water quality impact assessments, ysis model focuses on analyzing and formulating flood- Argonne National Laboratory has de~eloped the Ar- damage reduction measures other than traditional con- gonne Water Quality Accounting System (AQLJAS), a struction projects. new regional screening model. The model utilizes 178 ● Use of Models for Water Resources Management, Planning, and Policy streamflow data, measured water quality data, and re- Department of the Interior sidual discharge data at the accounting unit level to estimate changes in concentrations of selected pollutants. Bureau of Land Management (BLM) These several models are used by other agencies and organizations within and outside of DOE. BLM is responsible for managing, conserving, and The Strategic Environmental Assessment System developing 174 million acres of publicly owned land in (SEAS) is not a water resource model per se, but it cal- the 11 Western States and an additional 162 million culates wastewater residuals and regional water use for acres in Alaska, BLM also administers the subsurface energy scenarios during the course of general environ- minerals underlying approximately 370 million addi- mental assessments. DOE has supported Fish and Wild- tional acres throughout the Nation managed by other life Service development of an instream flow calcula- agencies or owned by private citizens, and on the 1.1 tion system to quantify the effects of water consumed billion acres of Outer Continental Shelf owned by the by the energy industry and to determine the effect on Federal Government. aquatic species, habitat, and the like. Its purpose is to BLM’s use of computer-based resource models is oc- estimate instream flow requirements that might con- casional, and is confined to selected models for site- strain energy development. specific analyses. Stochastic hydrologic models are used Aquifer modeling, though not a major program, is to evaluate alternate grazing systems in preparing graz- being developed to investigate the migration of polluting environmental impact statements. Hydraulic models ants, particularly radioactive materials, from waste- are used to evaluate instream flow needs for adjudicating disposal sites. Energy storage in aquifers has also been water rights, designing fishery habitat improvements modeled to determine geothermal reservoir dynamics and water facilities such as dams and water distribu- in support of this energy source. Other models investi- tion systems, and in analyzing overburden materials gate the effects of thermal energy releases on localized associated with surface mining. In addition to these meteorology —including effects on rainfall and cloud for- models, BLM uses technological guidelines developed mation—which could influence water supply. through the use of hydrologic models to analyze various resource problems, including timber harvesting and Federal Energy Regulatory Commission (FERC) planting techniques and their impacts on water quantity and quality; fishing improvements associated with FERC in DOE uses models under two major pro- spawning areas; flood plain identification; soil erosion; grams of the Federal Power Act (16 U.S.C. 803(f)): analysis of potential mineral leasing tracts; and the siting Dam Safety and Headwater Benefits. of campgrounds associated with water-based recreation. A number of models are used to plan or evaluate proj- BLM currently contributes financially to research ects under the Dam Safety Program. Some determine within USDA and the Department of the Interior, as water surface profiles and downstream water velocities well as to various university investigators. These re- resulting from a dam break. Other models are used for search projects are expected to produce a series of water preparing flood hydrography, reservoir routing, and de- resource models that will be used on a continuous basis, sign analysis. and to develop an additional technological guideline to Payments under the Headwater Benefits Program are address routine multiple-resource problems. In addition, determined with information provided by models. These BLM expects to continue to use models developed by models are used to determine the energy gains at down- others for solving problems related to public lands. stream hydropower plants resulting from the operation of headwater reservoirs. Bureau of Mines FERC also indicated model use for its cooperative activities program under the Water Resources Planning The Bureau of Mines’ principal responsibilities are Act, and for its participation in planning Federal water to develop mineral resources, promote mine safety, and resources projects under the Flood Control Act of 1936 maintain healthful working conditions and environmen- and amendments. Models are used to plan, evaluate, tal quality in the mineral industries. The bureau is con- and review projects, and for data acquisition, statistical cerned with the quality of water discharges in all phases analysis, and water resources/hydropower system anal- of mineral production, and it engages in research to de- ysis. velop and improve mining technology, including meth- App. B—Summary of Model Use by Individual Federal Agencies ● 179 ods of protecting water resources used or affected by hydrologic regime to determine regulations and stand- mining. ards for protecting water quality and quantity. This The bureau uses models in two of the programs it car- information is provided to State and local agencies and ries out related to the Clean Water Act, section 107, to private sector interests. Under section 510 of the act, which authorizes mine-water pollution control demon- the office uses models to evaluate permit applicants’ stration projects. Models are used to predict the effects assessments of the hydrological consequences of their of iron ore mining in the Mesabi Range of Minnesota proposed mining activities, and as a basis for approv- on the area’s hydrologic system. Another program in- ing or denying permits. The office aiso uses models to volving model use is designed to develop management evaluate protection of the hydrologic balance under the practices to minimize water quality problems during and environmental protection standards set pursuant to sec- after open pit mining of copper ore in Arizona. The in- tion 515 of the Surface Mining Control Act. formation these models generate is furnished to mining companies to help them comply with mine-water pollu- Office of Water Research and tion regulations. Technology (OWRT) The bureau also uses models in several other programs concerned with the effect of mining on water The principal functions of OWRT are to improve quality. These programs stem from various acts deal- technologies and methods for addressing water resource ing with water resources: problems, train water scientists and engineers, coordi- Under the Safe Drinking Water Act (Public Law nate water research, and disseminate water resource in- 93-523), section 1421 —the bureau has used models formation. These tasks, carried out under the State In- to help predict the effects of surface coal mining stitute Program by university water resources research on the ground water regime of western Tennessee. institutes in each State, are aimed at resolving local, This information is made available to mine opera- State, and regional water and water-related problems. tors to aid them in complying with existing regu- The State water resources research institutes and the lations. State Institute Program are described in detail in chapter Under the Surface Mining Control and Reclama- 4 of this report. tion Act, section 515—the bureau is using models Because OWRT is not a mission-oriented agency, it to predict the effect of coal mining on hydrologic does not itself use water resource models. It is active regimes in Coshocton, Ohio. in funding model development, however. Water re- Under the Resource Conservation Act, section 6— source models developed by OWRT grantees and con- the bureau uses models to predict the effects of coal tractors span almost the entire range of issue areas and mining on the hydrologic system, particularly model uses. At present, OWRT is assessing the need ground water, in the Power River Basin in Wyo- to develop simpler, less data-intensive models than those ming. This information is also made available to that now exist. A concomitant concern is to adapt exist- mine operators to assist them in preparing EISS, ing models to specific applications. and in complying with regulatory standards set by different agencies. This work is also related to the Fish and Wildlife Service Surface Mining Control and Reclamation Act. One Bureau of Mines model, UNSAT2, is used to The primary responsibilities of the Fish and Wildlife Service consist of conserving and protectin fish and predict seepage patterns and quantities from mine-waste g impoundments. Applications of this model include anal- wildlife resources and ensuring their equal consideration with other aspects of water development plannin yses of the stability of spent oil shale deposits and the g flow of leachates into ground water systems. as required by the Fish and Wildlife Coordination Act (16 U.S.C. 661). The service has a vital interest in water Office of Surface Mining and related land-use programs, including diversions, impoundments, facilities development, and streamflow The Office of Surface Mining administers portions regulation. The service participates actively in studies of the Surface Mining Control and Reclamation Act, leading to the formation of national, regional, or river using models in connection with several of its programs basin plans for using water and related land resources. under title V of the act—Control of the Environmental The service uses models in several of its programs Impacts of Surface Coal Mining. concerned with managing water resources for the benefit Section 515 authorizes environmental protection per- of fish and wildlife. When asked to analyze construc- formance standards for surface coal mine reclamation. tion projects and alternatives proposed by other agen- The office and its contractors use models in assessing cies in EISS, the service uses models to project the rel- the cumulative effect of surface coal mining on an area’s ative impacts of the proposed construction and its alter- 180 ● Use of Mode/s for Water Resources Management, Planning, and Policy natives over a number of years. Models also help deter- flood control, navigation preservation, propagation of mine the potential effects of a project on endangered fish and wildlife, outdoor recreation, drainage, pollu- and threatened species, as well as on water flow require- tion abatement, water quality control, streamflow aug- ments for these species. The service also uses models mentation, watershed protection, and erosion control. in surveys and investigations of the fish and wildlife im- All the bureau’s water and land resource development pacts of water resource projects under the Federal Recla- activities are authorized under the Federal Reclamation mation Act (43 U. S.C. 421 and 422), dealing with irri- Act (43 U.S.C. 421). gation distribution systems and construction of small During the last 15 years, considerable attention has water resource projects, respectively. been directed toward developing and managing Western The Fish and Wildlife Service uses models for several resources. As a result of this attention, a large body of purposes in its programs in accordance with the Fish water-related legislation has been passed that relates to, and Wildlife Coordination Act. Under this legislation and has some impact on, the basic water and land re- the service recommends modifications in project design sources development mission of the bureau. Sections and operation consistent with sound wildlife manage- 208, 209, and 303 of the Clean Water Act require the ment principles. bureau to consider areawide wastewater treatment facil- Some of these uses are: ities and management, river basin planning and man- ● For water resources planning: the service uses agement, and quality standards and implementation in models to help assess water availability and in- plans, respectively. The National Environmental Policy stream flows, to predict the effects on habitats sur- Act of 1969 in section 102 requires evaluation of im- rounding such projects, and to assess the impacts pacts from water resource development projects both of water development projects. during construction and for the long term. ● For operation and management activities: the serv- The Colorado River Salinity Control Act was estab- ice uses models to help determine waterflow re- lished to define and implement effective salinity control gimes and how to mitigate impacts from construc- measures to meet established water quality standards. tion projects. Other legislative acts affecting the bureau’s water re- The service also acts in an advisory capacity to State source development activities include: the Endangered and local agencies that use models to assess instream Species Conservation Act; Executive Order No. 11988, flow needs and the effects of construction and energy- sections 2 and 3 (flood plain management); the Water related activities on aquatic populations. Resources Development Act, section 73, (nonstructural For evaluating the effects of powerplant design and measures); and the Flood Control Act (building flood siting, the Fish and Wildlife Service principally uses two control structures). types of models. One type includes fairly large simula- To assist in accomplishing its basic water and land tion models for investigating and predicting physical im- resource planning, development, and management mis- pacts of powerplant operation (specifically, cooling) on sion, the Bureau of Reclamation has developed several the aquatic environment. Such impacts include fish water resource-related models. These models are used entrainment-impingement, as well as habitat modifica- in the planning, design, and operational phases of the tion. The service also uses a Multiple-Objective Pro- agency’s mission, and are employed extensively to eval- graming (MOP) model to study regional alternatives uate the effects of planned actions as they relate to and for powerplant location. The regional energy location affect the legislation described previously. These models model (RELM) was recently modified to incorporate were not developed for any specific legislation or as a biological/ecological considerations into an economic op- result of it, but are used as tools to assess the impacts timization model. This modified model is intended to of planned actions or change in operating strategies to include ecological criteria in siting decisions at the see how they relate to and comply with the various stat- earliest possible planning stage, thus reducing the like- utes. lihood of expensive litigation over the development of The bureau uses physical/ecological ground and sur- future energy resources. face water models, as well as various economic/social models. All of the bureau regional offices and many of its project offices use surface water models. These Bureau of Reclamation models are usually developed or adapted by the office using them. Most of these models are project-specific, The Bureau of Reclamation is involved in develop- and simulate project operations over various time peri- ing water and related land resources in the 17 Western ods and with various hydrological inputs. The models States. Planning such development is a multiobjective are used for single projects, multiple projects, or entire and multipurpose activity directed at irrigation, munic- river basins. Model applications include developing res- ipal and industrial water supply, hydroelectric power, ervoir operation strategies; hydropower simulation; and App. B—Summary of Model Use by Individual Federal Agencies ● 181

water quality, water rights, water availability, and flood The bureau also uses a wide variety of ground water control studies. models in water resource planning, system design, and The bureau uses models to help determine how tem- project operation. With few exceptions, these are theo- perature changes or peaking power releases resulting retically based models that simulate the movement of from various reservoir operation, release, and withdraw- both water and solutes. al schemes would affect downstream fisheries and recrea- A major recent effort by the Bureau has been to devel- tion and power users. This information is communicated op and implement the Bureau of Reclamation Economic to States, localities, and other Federal agencies so that Assessment Model (BREAM), a simulation-type model. reservoir operations can comply with State and Federal BREAM’s basic function is to provide a systematic, fish habitat temperature guidelines, optimize power gen- theoretically sound approach to projecting population, eration, and meet water user contract agreements. employment, and income. The bureau envisions using Models are also used to evaluate the impact of reser- BREAM principally for alternative futures analyses, voir and stream operations on fish habitat and popula- public involvement, projection of municipal and indus- tions. trial water requirements, and economic/demographic The bureau makes extensive use of simulation models impact assessments related to water resource construc- to evaluate the impacts and effectiveness of irrigation tion activities and long-run uses and outputs of water systems. The models provide information for determin- resource development. The economic and demographic ing whether projects should be modified to exclude lands outputs of BREAM are also major inputs and driving that irrigation would affect adversely. They are also used variables necessary for evaluating the social impacts of to help predict the quality and quantity of irrigation water resource development activities. The bureau uses return flows and the effects of project development on other economic models to analyze and optimize farm aquifer quality, receiving stream quality, and chemical, enterprises in determining irrigation benefits and pay- physical, and biologic properties of project soils. The ment capacity, and to analyze hydropower additions to Return Flow Quality Simulation model has been used existing power system networks. to calculate salinity and other ground and surface water The bureau has also developed data management and quality changes from major irrigation projects in Cali- scheduling systems based on models of management fornia, Colorado, and the Dakotas. This model can also functions. These provide for scheduling program activ- be used to schedule the timing and amounts of water ities, and funding and manpower requirements. required for a variety of crops and climates. Models are used in developing salinity level stand- U.S. Geological Survey (USGS) ards and in evaluating the effects of specific actions on salinity levels in the Colorado River Basin. Specifical- USGS conducts research on the physical features of ly, the models estimate the effect of future water uses the Nation, including its mineral and water resources. on salinity and the cost effectiveness of salinity control This research is based on the fields of hydroloW, geol- measures for meeting established standards. The models ogy, geochemistry, and geophysics, and aims at develop- also help determine the technical feasibility of proposed ing new technologies and methods for appraising and salinity control measures at point, nonpoint, and agri- conservin g minerals and water. The Water Resources cultural sources. In addition, the models are used to Division of USGS is responsible for investigating and develop operating strategies for reservoirs, determine appraising the source, quantity, quality, distribution, the optimum size of desalting plants and reservoirs, and movement, and availability of both ground and surface maximize the water supply for all competing uses, in- water. The legal authority for this work stems from the cluding power, municipal and industrial, irrigation, in- act of October 2, 1881 (25 Stat. 505, 526), augmenting stream flows for fisheries and recreation, and water qual- the organic act establishing USGS in 1879, and has been ity. reinforced by the general language of annual appropria- Other types of surface water models used by the bu- tion acts for the Department of the Interior since 1894. reau include unsteady flow routing models to predict AIso, USGS has been the indirect recipient of program outflows and downstream routings of floods from hypo- responsibilities under many different water resource laws thetically breached dams. These models assist in devel- that are primarily directed toward resource management oping maps of expected inundation areas for emergency agencies. preparedness planning. The bureau also employs and USGS uses models in connection with many of its continues to develop synthetic models to describe ex- programs. Models are used to study flow, ion transport, treme storm precipitation and meteorologic conditions. and geochemistry in aquifer systems; information thus These are used to determine maximum probable flood generated is made available to Federal and State agen- values for sizing spillways and to describe atmospheric cies, and to the general public. Modeling activities of modification potential for precipitation augmentation. the USGS Water Resources Division—in particular, the 182 ● Use of Models for Water Resources Management, Planning, and Policy

Federal-State Cooperative Program—are described in ● The Water Resources Development Act of 1974: detail in chapter 4 of this report. Models are used in — section 73—nonstructural measures. connection with USGS activities relating to sections of ● The Federal Reclamation Act: the Clean Water Act, namely: — 43 U.S.C. 421—irrigation distribution systems. ● section 201 —grants for construction of treatment USGS has made significant contributions to the devel- plants; opment of models for analyzing ground water problems. . section 3 I l—oil and hazardous substances liability; Specific areas include: physical characteristics of ground . section 3 14—clean lakes; water flow, effects of ground water depletion on surface . section 3 16—thermal discharges and exemptions; lands, flow in coupled ground water/stream systems, in- and tegration of rainfall-runoff basin models with soil mois- . section 404—guidelines and permits for use of ture accounting and aquifer-flow models, interaction of dredge or fill materials. economic and hydrologic considerations, prediction of USGS also develops models for use by itself and pollutant transport in aquifers, and estimation of the others in programs under the Resource Conservation effects of development schemes for geothermal systems. and Recovery Act (Public Law 94-580). USGS is actively involved in updating and improving USGS develops models to study many aspects of qual- most of these models. ity in selected rivers of the United States. These models USGS surface-water modeling efforts include: flow analyze flow and transport, dissolved oxygen, and ther- routing in streams, estuaries, lakes, and reservoirs; sedi- mal discharges. Use of these models is generally related mentation; transport of physical, chemical, and bio- to provisions of the Water Resources Planning Act, logical constituents; coupled stream-aquifer flow sys- which requires a continuing study of the adequacy of tems; physical hydrology for rainfall-runoff relations, the Nation’s water supply. USGS is also developing stream simulations, channel geometry, and water qual- models that will be used to assess the impact of surface ity; statistical hydrology for synthetic streamflows, coal mining on the hydrology of mined river basins, an floods, reservoir storage, and water quality; manage- activity relating to section 515 environmental protec- ment and operations problems; and water quality prob- tion standards under the Surface Mining Control and lems that result from environmental pollution, such as Reclamation Act. thermal loading, pesticide pollution, and freshwater USGS is also concerned with flood control and uses eutrophication. models in connection with its activities under the Flood Control Act and sections 2 and 3 of Executive Order Independent Agencies No. 11988, dealing with flood plain management. USGS models determine flood discharges for specified Council on Environmental Quality (CEQ) recurrence intervals, flood profiles, and flood routings. The information the models produce is available to ap- CEQ has responsibilities for national overviews of propriate Federal, State, and local authorities and to environmental quality conditions and trends. To satisfy the public. these responsibilities, CEQ with the cosponsorship of In addition to these uses of models, USGS indicated other agencies and organizations, has developed the that it uses or is developing models in connection with UPGRADE computerized environmental analysis sys- its activities under the following acts: tem. This system of models and data bases is used to ● The Safe Drinking Water Act (Public Law 93-523): analyze water quality, air quality, environmental health, — section 1421—protection of underground and socioeconomic data. The system permits cross-anal- sources of drinking water; and ysis (e. g., water pollution vs. health) at the county level. — section 1444—special study and demonstration It is an interactive system and is completely English- project grants for wastewater reuse, reclama- language prompted. Data bases on wide-ranging sub- tion, and recycling processes. ject areas are being added to the system in order to The Surface Mining Control and Reclamation Act: broaden and deepen the system’s analytical capabilities. — section 506—surface mining permits; and — section 5 15—environmental protection stand- Environmental Protection Agency (EPA) ards for reclamation. ● The Resource Conservation Act: The responsibilities of EPA include establishing and — section 5—data collection about soil, water, and enforcing environmental standards, conducting research related resources; on the impacts of pollution and ways to control it, and — section 6—soil and water conservation pro- assisting CEQ in developing and recommending to the grams. President new policies for protecting the environment. App. B—Summary of Model Use by Individual Federal Agencies ● 183

With respect to water resources, EPA is concerned with oping guidelines for toxic and pretreatment effluent providing water supplies that are adequate in quality standards pursuant to section 307 of the Clean Water for all beneficial purposes. The following EPA offices Act. The models OWRS currently uses address three indicated use of water resource models in connection main problem areas: the fate of pollutants discharged with program responsibilities. into receiving waters, and their effect on water quality; 1. Office of Research and Development (ORD)— the quantity and quality of runoff from urban and agri- ORD is actively involved in developing and using water cultural areas, and its impact on receiving waters; and resource mathematical models and predictive tech- the economic effects of water pollution regulations on niques. The major thrust of its modeling activity is to industries. develop capabilities to translate water quality standards A principal model in the first category is EXAMS. into maximum allowable pollution loadings, select the The Water Quality Analysis Branch of OWRS currently most cost-effective combination of controls, and assess uses EXAMS to evaluate different control strategies for environmental risks associated with production, trans- selected pollutants in order to determine whether these port, use, and disposal of toxic chemicals. ORD has con- pollutants should be subject to best available technology ducted special studies of the Great Lakes, Chesapeake (BAT) requirements or to more stringent controls. The Bay, James River, and other areas where other EPA EXAMS model is being used in conjunction with agri- offices have requested technical assistance. cultural runoff models, such as ARM-II, and receiv- Two principal types of models have been developed ing-water quality models, such as QUAL-H, for screen- as part of the ORD Great Lakes program. The first, ing analyses of new pesticides. a series of physical/ecological models, focus on the re- Another major use of models of this type is in estab- lationship of phytoplankton biomass to nutrient load- lishing and enforcing wasteload allocations for National ings. These models were developed to understand and Pollutant Discharge Elimination System (NPDES) per- control accelerated eutrophication in portions of the mits. These models are used to assess the assimilative Great Lakes; they are being used to recommend guide- capacity of a water body and to relate stream water qual- lines for nutrient discharges. The second type of model ity levels to pollutant discharges. The models are also describes the transport and fate of toxic pollutants in- used to determine whether dischargers are complying troduced into the Great Lakes, in order to determine with permit allocations. the levels of control required to keep environmental risks OWRS’S Office of Analysis and Evaluation assesses within acceptable levels. the economic impact of water pollution regulation on ORD has also developed nonpoint source, toxic pol- industrial sectors by one of two techniques, depending lutant, eutrophication, and circulation models for the on industry size. For small industries, the office performs Chesapeake Bay. These address the problems of acceler- industry-specific financial analyses to determine if com- ated eutrophication in portions of the bay, the decline pliance with point-source BAT regulations will force of submerged aquatic vegetation, and associated impacts firms to close. The office uses econometric models to on aquatic life and commerce. study larger industries. These models deal with capital ORD assists EPA’s operational programs in selecting requirements, pricing, future demand for products, and and using models to deal with specific problems. These the effects of regulation on industry growth. models include urban and rural runoff models and re- 3. Office of Water Program Operations (OWPO)— ceiving-water quality models. The models are used in Urban and agricultural runoff models are used to a lim- determining control requirements to be placed on dis- ited degree by the national office of the Water Planning charges and in planning studies required under section Division of OWPO in planning studies. These models 208 of the Clean Water Act. ORD also provides techni- are used at the State level to estimate potential runoff cal assistance with the Exposure Analysis Modeling Sys- and to evaluate different pollution control strategies, as tem (EXAMS), a major mathematical model for assess- required under section 208 of the Clean Water Act. ing the primary pathways, persistence, and fate of toxic 4. OffIce of Water and Waste Management—EPA’s organic chemicals in freshwater systems. Drinking Water Program in the Office of Water and Future water resource modeling needs ORD is ad- Waste Management has the responsibility to implement dressing concentrate on providing the capability to assess provisions of the Safe Drinking Water Act, and it uses environmental risks associated with toxic chemicals in some models to improve the decisionmaking process. ground and surface water, and identifying cost-effective Under section 1412, for example, it uses health effects pollution control measures to attain and maintain water models as part of the background information base for quality goals. setting standards and promulgating regulations. These 2. Office of Water Regulations and Standards models provide data on the health risk from exposure (OWRS)—EPA’S OWRS uses some models in devel- to contaminants in drinking water. Information from 184 . Use of Models for Water Resources Management, Planning, and Policy

such models has been used in the standard-setting proc- 5. Office of Toxic Substances (OTS)—EPA’S OTS ess for radioactive and organic contaminants. The pro- uses models in several of the programs it carries out gram also uses economic and benefit/cost models to under current water resource legislation. The principal determine the economic effects of alternative policy and focus of its model use is the transport and fate of toxic regulatory options on the water supply industry. chemicals released into the aquatic environment. Cur- Protection of underground sources of drinking water, rently, models are being used in OTS for risk assess- prescribed in section 1421 of the Safe Drinking Water ment studies, to estimate the movement of pollutants Act, is also a responsibility of the Drinking Water Pro- through the environment and their expected environ- gram. Hazardous and toxic wastes have frequently been mental concentrations. The office uses models in con- disposed of through injection into underground forma- nection with activities under the Toxic Substances Con- tions. The program uses models to provide information trol Act. Its models help measure the effectiveness of on the impact of injection practices on the natural sys- regulatory options in order to set standards according tem, the costs of constructing new wells, and the eco- to sections 4, 5, and 6 of the act, which deal with test- nomic costs of shutting down existing wells. By comparing, issuing manufacturing and processing notices, and ing regulatory and remedial alternatives available, pro- regulating hazardous chemical substances and mixtures. grams can be developed to balance the risks and costs OTS uses a three-step analysis to determine whether of contamination prevention measures. a substance should be regulated, and, if so, how strin- The Drinking Water Program has also conducted a gent the regulation should be—such regulation could major surface impoundment assessment authorized by range from labeling a substance as hazardous to ban- section 1442 of the act. The assessment includes a na- ning its use entirely. The office first determines the ex- tionwide survey of surface impoundments in order to posure of human and nonhuman populations to the toxic determine their potential for contaminating ground substance. It then combines this exposure information water. Uniform criteria were developed and used to with estimates of health and ecological effects for various assess current and potential leakage of contaminants into exposures. Finally, the office weighs these costs against ground water. These criteria include, among others, the benefits of using the substance. Models are used in type of geology underlying the site, type of waste in- accomplishing the first step of the analysis. volved, proximity of aquifers, and capability of soil to In addition to this use of models, OTS uses models attenuate pollutants. Based on data collected, ground to help design chemical testing programs and to develop water models can be developed to account for these fac- monitoring studies carried out under provisions of the tors in predicting an impoundment’s potential for con- Toxic Substances Control Act. taminating ground water. OTS is also involved in programs under the Federal The Drinking Water Program also uses models to Insecticide, Fungicide, and Rodenticide Act of 1972 evaluate State needs and capabilities in order to deter- (Public Law 92-516), and uses models in conducting mine the appropriate grant amounts States receive these programs. In its review of pesticide product regis- under section 1443 of the Safe Drinking Water Act. trations, OTS must consider the potential effect of the These are financial models, but they take into considera- substance on ground and surface waters. In this con- tion such factors as the number and type of injection nection, OTS uses models to assess pesticide runoff wells in the State, the number of wells used as part of potential and the likelihood of ground water contamina- a water supply system, the geographic area, and the tion by pesticides, and to predict pesticide concentra- manpower available in the State. tion in streams. OTS also uses models for advising State Models have also been used to develop a more com- and local agencies of the likelihood of ground water con- plete understanding of sole-source aquifers. These tamination by pesticides. ground water resources may, in some parts of the coun- OTS mainly uses the EXAMS model, although its try, provide the only available source of water. Models Evaluation Division makes limited use of ARM-II in provide information on the impact of discharges and pesticide screening studies. OTS is developing multi- other economic activities on these sources of drinking media (water, air, land) models for preliminary assess- water. Facilities that may adversely affect these aquifers ments of a chemical’s behavior in the environment. include: leaking underground gasoline storage tanks, These models provide concentration estimates used in waste disposal sites, improper land use, construction of the exposure calculations that support risk analysis. The roads and buildings in the recharge zone, and pollution multimedia formulations are capable of accommodating of adjacent streams. Once the relative impacts of sources various types of chemicals and modes of release into the of contamination are determined and evaluated, EPA environment. In addition, two ground water contamina- works with State agencies and communities to establish tion models are being developed for OTS. and enforce procedures to prevent future aquifer con- 6. Office of Water Enforcement—EPA’s Office of tamination. Water Enforcement uses models in connection with its App. B—Summary of Model Use by Individual Federal Agencies ● 185

activities under the NPDES permit program and sec- national water assessments to identify the Nation’s criti- tions 301 and 316 of the Clean Water Act. The NPDES cal water problems. program under section 402 of the Clean Water Act re- For its Second National Assessment in 1978, WRC quires issuance of permits to regulate discharge of pol- developed a water supply adequacy model. This model lutants into the Nation’s waters. Permit limits are either is based on the concept of a balance between water use technology or water quality based. When technol- and water supply for both ground and surface water. ogy-based limits are unavailable or inadequate to meet The model is comprised of 21 water resource regions water quality standards, permits are based on ‘‘best pro- and 106 subregions. The subregions have data on water fessional judgment, ’ which may include the use of inflow or supply from upstream subregions, interbasin wasteload allocation or other water quality models. In imports, precipitation runoff, and ground water. Water addition, water quality models, dispersion models, and uses include interbasin exports, consumption, and hydrological models are used to measure compliance evaporation. Ground water recharge is accounted for with water quality standards. in the model and is not considered a loss. The hydrologic Under section 316 of the Clean Water Act, which and water-use data fed into this model were derived authorizes variances from thermal discharge standards, through models incorporating precipitation records, the office uses predictive studies of entrainment and im- runoff estimates, economic growth projections, and pingement losses to populations of fish and shellfish in other measured or calculated variables at the water- enforcing regulations governing powerplant siting. It accounting-unit level (352 nationwide). These models also uses fish population models and hydrological models were produced or operated for WRC by various Federal, for the cooling intake structures program. State, and regional agencies. Section 301, which includes environmental and eco- The water supply adequacy model helped identify nomic variances, demands the use of models when pre- several water supply problems. These included shortages dictive demonstrations are needed to establish ambient resulting from poor distribution of supplies, instream - concentrations of nonconventional pollutants. offstream conflicts, competition among various offstream users, ground water overdraft, quality degrada- tion of ground and surface water, and institutional con- National Science Foundation (NSF) flicts that prevent a unified approach to water management. NSF does not use water resource models, nor does WRC’S Water and Energy Program was authorized it directly fund the development of specific models. It by the Federal Nonnuclear Energy Research and Devel- does, however, fund basic research at universities that opment Act of 1974 (sec. 13 of Public Law 93-577), may contribute to the formulation of water resource which directs WRC to conduct regional and site-specific models. Such research may also produce components water resource assessments of potential energy develop- and mathematical techniques that can be used in de- ments. For this purpose, a number of computerized veloping such models or in checking their scientific models have been used by various WRC contractors and validity. other Federal and State agencies, e.g. , the Colorado The research NSF funds in the area of water resources River System Simulation (CRSS) of the Bureau of is for the purpose of building a firm scientific founda- Reclamation and the respective models of the White tion, wherever possible, for empirical procedures and River developed separately by Utah and Colorado. practices that are used in developing water resource These, and similar models, evaluate flow regime, hydro- models. Well-known examples are rainfall-runoff rela- power impacts, salinity and suspended solids concen- tionships and rainfall-soil erosion relationships. trations, and other water quantity and quality changes NSF responds only to unsolicited basic research pro- anticipated from energy developments. posals in water resource engineering. During fiscal year WRC presently evaluates river basin plans pursuant 1979, NSF supported hydrologic and water resource to section 209 of the Clean Water Act. It is testing a studies on hydrologic data, irrigation, planning, flood model that assesses water quality impacts of existing or forecasting, reservoir control, and surface runoff, among proposed river basin management schemes—specific- others. Any or all of these topics may have models as- ally, in its Yadkin-Pee Dee Level-B study. sociated with the project. Some river basin commissions under the purview of WRC use models to help plan or evaluate projects devel- Water Resources Council (WRC) oped under section 102 of the Water Resources Plan- ning Act. This section deals with regional or river basin WRC encourages Federal, State, and local govern- plans and programs and their relationship to other con- ments and private enterprise to conserve, develop, and siderations. The commissions use models to analyze the use water and related land resources on a comprehen- impacts of potential projects on water supply, to esti- sive and coordinated basis. WRC also conducts periodic mate depleted flows at key gaging stations, and to com- 186 . Use of Mode/s for water Resources Management, Planning, and Policy

pare the cost effectiveness of alternative wasteload reduc- transport in ground and surface waters. NRC has used tion strategies. models in connection with all of these programs. For example, to comply with regulations under section 102 Federal Emergency Management Agency of the National Environmental Protection Act, NRC used models to evaluate powerplant intake effects on The Federal Emergency Management Agency, Hudson River striped bass. through the Federal Insurance Administration (FIA), NRC has specific responsibilities under the Uranium administers the National Flood Insurance Program as Mill Tailings Radiation Control Act and the Atomic En- established by the National Flood Insurance Act of 1968 ergy Act. Under the first act, NRC uses models to deter- (Public Law 90-488). The program provides flood insur- mine the movement and concentration of ground water ance availability to property owners within communities pollutants from uranium mill tailings. Information pro- that adopt and enforce minimum flood plain manage- vided by these models was used to prepare a generic en- ment measures to mitigate future flood losses. The act vironmental impact statement on uranium milling and also requires the identification of flood-prone areas and associated rule changes. NRC also uses models to sup- risk zones within such areas. port various licensing actions. Models help support Flood insurance studies are conducted for individual licensing decisions for uranium mills, tailings disposal communities to establish flood plains, floodways, regu- systems, and uranium extraction operations. Models latory flood elevations, and insurance risk zones. These also help measure compliance with regulations and li- data are often developed using models and are subse- cense conditions. quently provided to participating communities as the Under the Atomic Energy Act, NRC uses models to basis for their flood plain management program. They help it evaluate proposed sites for nuclear powerplants, are also used to establish actuarial flood insurance rates. fuel cycle facilities, and waste disposal sites. Models are Several different hydrologic models have been used used to help determine whether a plant’s water supply by FIA to establish flood flow frequencies and for flood is adequate for safety-related functions, as specified in hydrography routing. The most commonly used hydro- regulations. NRC also uses models to evaluate whether logic models are the HEC-1 Flood Hydrography Pack- proposed nuclear facilities are in compliance with regula- age, developed by the Corps of Engineers, and the tions governing flood protection. TR-20 Computer Program for Project Formulation, de- Models have been used by NRC in carrying out its veloped by SCS. These models simulate the rainfall- responsibilities under the Atomic Energy Act to limit runoff process on watersheds and flood hydrography pro- radioactive liquid effluents to ground and surface waters. gression in downstream channels. NRC is using models to help prepare an EIS and to for- Several hydraulic models have been used to establish mulate proposed regulations governing the disposal of flood elevations and floodways in streams. The most low-level radioactive waste and low-activity bulk solid commonly used hydraulic models are the HEC-2 Water waste. The models are presently being used to evaluate Surface Profile Package, developed by the Corps of En- siting criteria and alternative disposal techniques in gineers, WSP-2 (TR61) and FLDWY (TR-64), devel- terms of radionuclide transport and concentrations at oped by SCS, and E431, developed by USGS. These site boundaries. When disposal site regulations are models simulate open channel steady uniform flow using adopted, site-specific models will be used to determine the standard step backwater method. whether adequate protection exists to prevent radio- FIA has also developed two coastal storm surge mod- nuclide migration from exceeding acceptable limits. els, including one for northeasters and one for hurri- Models are also used to help determine whether other canes. These models utilize joint probability techniques types of nuclear facilities are in compliance. These mod- and coastal hydrodynamic principles to establish regula- els help evaluate potential concentrations of radionu- tory flood elevations on the Atlantic and Gulf coasts of clides in ground and surface waters as a result of both the United States. A finite element model has also been accidental and normal releases. established to simulate storm surges in the Chesapeake NRC provides assistance to States in the use of models Bay. to evaluate radionuclide migration from disposal sites. This is done as part of the agreement State program, Nuclear Regulatory Commission (NRC) through which certain States, pursuant to section 274 of the Atomic Energy Act, have entered into an agree- NRC water resource activities are related to deter- ment with NRC for assuming regulatory control of by- mining hydrologic factors in nuclear facility site evalua- product, source, and small quantities of special nuclear tions, ecological effects of water use, and radionuclide materials. App. B—Summary of Model Use by Individual Federal Agencies . 187

ATTACHMENT I.—REFERENCES BY AGENCY

Department of Agriculture SCS-001 11, submitted to: SCS, USDA, June 1, 1978. Economics and Statistics Service 10. King, Arnold D., ‘‘Universal Soil Loss Equation, Soil Conservation Service, 1979. 1. Dyke, P., and Hagen, L., Resource Systems Pro- 11. Pasley, R. M., Dempster, T., Stierna, J., Cald- gram, Natural Resource Economics Division, ECO- well, B., King, A., and Evans, G., interviews with nomics, Statistics, and Cooperative Service, Soil Conservation Service and USDA personnel, USDA, Land and Water Resource and Economic Aug. 30, 1979. Modeling System, LA WREMS Directoxy, version 12. Soil Conservation Service, “Executive Summary 1, January 1979. of Responses to Objectives, USDA, Oct. 19, 2. Land and Water Conservation Task Force, 1979. ‘‘LAWREMS, Land and Water Resources and 13. Soil Conservation Service, Farmer Decision and Economic Modeling System, Current Capabilities, Conservation Simulation Model, draft RLC: PEB, Conceptual System, Future Options, Final Draft, ” USDA, Aug. 23,1979. USDA, December 1978. 14. Soil Conservation Service and Stanford Research 3. Weisz, R. N., National Systems Section, Natural Institute, draft, “Documentation of the SRI Meth- Resource Economics Division, Economic, Statis- odology for RCA Evaluation, September 1979. tics and Cooperative Service, USDA, October 15. Soil Conservation Service, West Technical Service 1979. Center, User’s Guide to the Irrigation Method Analysis Program, IRMA, Colorado River Basin Forest Service Salinity Control Studies and Irrigation Planning, 4. Forest Service, USDA (unknown title), sec. 2, Hy- USDA, February 1978. drologic and Soils Simulation Programs, pp. 16. Metcalf and Eddy, Inc. (sponsored in part by 32-65. USDA), Process Design Manual for Land Treat- 5. Group Leader, Watershed Systems Development ment of Municipal Wastewater, October 1977. Group, Forest Service, USDA, Userguide Ab- 17. Soil Conservation Service, USDA, “Land stracts. Damage Analysis, ” attachment, 1976. 18. Soil Conservation Service, Engineering Division, Science and Education Administration WSP-2 Computer Program, technical release No. 61, USDA, May 1976. 6. Data Systems Application Division of Agricultural 19. Soil Conservation Service, Special Projects Divi- Research Service, USDA, File of A.gricultural Re- sion, User Guide to the SCS Automated Irriga- search Models (FARM), November 1977. tion Water Use Requirements Model Utilized in 7. Knisel, W. G., “A Field Scale Model for Esti- the 1975 National Water Assessment Program, mating Chemicals, Runoff, and Erosion From USDA, May 1975. Agricultural Management Systems, Science and 20. Soil Conservation Service, Engineering Division, Education Administration, USDA. Urban HydroZogy for Small Watersheds, technical 8. Wischmeier, W. H., and Smith, D. D., “Predict- release No. 55, USDA, January 1975. ing Rainfall Erosion Losses—A Guide to Conser- 21. Soil Conservation Service, ‘ ‘Urban Floodwater vation Planning, Science and Education Ad- Damage, Economic Evaluation, attachment 28, ministration, USDA, agriculture handbook No. USDA, 1976.

537, 1978. 22. Soil Conservation Service, Engineering Division, Computer Program for Project Formulation, Soil Conservation Service Structure Site AnaZysis, technical release No. 48, USDA, February 1971. 9. Ecology Simulations, Inc. , Athens, Ga. , 23 Soil Conservation Service, Economics Division, “SECWATS: A Simulation Concept and Model ECON2, Economics—Floodwater Damages, pro- for Assessment, Evaluation and Optimization of gram description, Apr. 1, 1969. Southeastern Coastal Plain Stream Modification 24, Soil Conservation Service, Engineering Division, Projects, With Application to Horse Range Computer Program for Project Formulation, Hy- Swamp, South Carolina. ” contract No. AG drology, technical release No. 20, 1965. 188 ● Use of Mode/s for water Resources Management, Planning, andPolicy

25. Soil Conservation Service, Applied Conservation 106 (Cincinnati, Ohio: Environmental Protection Effects System, briefing paper, USDA. Agency, 1976). 35 Twedt, T. M., Schaake, Jr., J. C., and Peck, Department of Commerce E. L., “National Weather Service Extended Streamflow Prediction, ” in Proceedings of the NOAA: National Weather Service Western Show Conference, Albuquerque, N. M., Apr. 19-31, 1977. 26. Curtis, D. C., and Schaake, Jr., J. C., “The NWS Extended Streamflow Prediction Technique, ” presented at the Engineering Foundation Conference: Department of Defense Water Conservation-Needs and Implementation Strategies, held at Franklin Pierce College, U.S. Army Corps of Engineers Rindge, N. H., July 9-13, 1978. 27. Fread, D. L., ‘ ‘National Weather Service Opera- 36. Boyd, M. B., ‘‘Response to OTA Questionnaire: tional Dynamic Wave Model, presented at Nu- Task Force on Water Resource Modeling in Fed- merical Modeling for Engineers Symposium, eral Agencies, personal correspondence, October Vicksburg, Miss., U.S. Army Corps of Engineers, 1979. Waterways Experiment Station, Apr. 17-21, 1978. 37. Eichert, B. S., and Bonner, V. R., HEC Con- 28. Fread, D. L., ‘ ‘The NWS Dam-Break Flood Fore- tribution to Reservoir System Operation, technical casting Model, presented at Dam-Break Model- paper No. 63 (Davis, Calif.: Hydrologic Engineer- ing Seminars at Kansas City, Mo., Sept. 18-22, ing Center, U.S. Army Corps of Engineers, 1978. August 1979). 29. Hydrologic Research Laboratory, National 38 Gundlach, D. L. and Thomas, W. A., “Guide- Weather Service River Forecast System Forecast lines for Calculating and Routing a Dam-Break Procedures, NOAA technical memorandum Flood, ‘‘ research note No. 5 (Davis, Calif.: NWS-HYDRO-14, Silver Sring, Md., Depart- Hydrologic Engineering Center, U.S. Army Corps ment of Commerce, 1972. of Engineers, May 1977). 30. Krsysztofowicz, R., Davis, D. R., Ferrell, W. R., 39, Hydrologic Engineering Center, Urban Storm- Hosne-Sanaye, S., Perry, S. E., and Robotham, water Runoff ‘STORM, Generalized Computer H. R., “Evaluation of Flood Forecasting Response Program 723-58-62520 (Davis, Calif., Hydrologic Systems II, report to Hydrology Laboratory, Of- Engineering Center, U.S. Army Corps of Engi- fice of Hydrology, National Weather Service, neers, May 1976). NOAA, Department of Commerce, contract No. 40, Hydrologic Engineering Center, Computer Pro- 6-35229, Reports on Natural Resource Systems gram Abstracts (Davis, Calif.: Hydrologic Engi- No. 33, University of Arizona, Tucson, Ariz., neering Center, U.S. Army Corps of Engineers, 1979. December, 1978). 31. Office of Hydrology, National Weather Service, 41, Hydrologic Engineering Center, “Response to “Response to OTA Questionnaire: Task Force on OTA Questionnaire: Task Force on Water Re- Water Resource Modeling in Federal Agencies, source Modeling in Federal Agencies, personal personal correspondence, October 1979. correspondence, October 1979. 32. Ostrowski, J. T., National Weather Service, 42, Robey, D. L., “Response to OTA Questionnaire: “Products Useful for Reservoir Regulation, ” Task Force on Water Resource Modeling in Fed- Hydrologic Research Laboratory, National eral Agencies, personal correspondence, October Weather Service, NOAA, Silver Spring, Md., 1979. mimeograph, 1979. 43, Roesner, L. A., Nichandros, H. M., and Shubin- 33. Peck, E., and Hudlow, M., staff, Ofilce of Hydrol- ski, R. P., ‘‘A Model for Evaluating Runoff-Qual- ogy, National Weather Service, NOAA, Depart- ity in Metropolitan Master Planning, technical ment of Commerce, personal interview, Aug. 29, paper No. 58 (Davis, Calif.: Hydrologic Engineer- 1979. ing Center, U.S. Army Corps of Engineers, April 34. Schaake, Jr., J. C., “Use of Mathematical Models 1974). for Hydrologic Forecasting in the National 44, Walski, Thomas M., “MAPS-A Planning Tool Weather Service, ‘‘ in Proceedings of the EPA Con- for Corps of Engineers Regional Water Supply ference on Environmental Modeling and Simula- Studies, ” Water Resources Bulletin, vol. 16, No. tion, W. R. Ott (cd.), report No. EPA-600 /9-76- 2, April 1980. App. B—Summary of Model Use by Individual Federal Agencies 189

Department of Energy U.S. Fish and Wildlife Service 55. Hyra, Ronald, ‘ ‘Methods of Assessing Instream Office of the Environment Flows for Recreation, ” FWS/ORS-78/34, Fish 45, Osterhoudt, Frank H., “Response to OTA Ques- and Wildlife Service, Fort Collins, Colo. , June tionnaire: Task Force on Water Resource Model- 1978. ing in the Federal Agencies, personal correspond- 56. U.S. Fish and Wildlife Service, annotated list of ence, November 1979. water resource models developed for or by the U.S. 46, Owen, P. T., Dailey, N. S., Johnson, C. A., and Fish and Wildlife Service, 1979. Martin, F. M., ‘ ‘An Inventory of Environmental 57. U.S. Fish and Wildlife Service, “Response to Impacts Models Related to Energy Technologies, OTA Questionaire: Task Force on Water Re- ORNL/EIS-147, February 1979. source Modeling, personal correspondence, Oc- 47, Shepard, A. D., “A Spatial Analysis Method of tober 1979. Assessing Water Supply and Demand Applied to Energy Development in the Ohio River Basin, ” ORNL/TM-6375, August 1979. U.S. Geological Survey 48, Shriner, C. R. and Peck, L. J. (eds. ), “Inventory 58. Appel, Charles A., and Bredehoeft, John D., of Data Bases, Graphics Packages, and Models in “Status of Ground-Water Modeling in the U.S. Department of Energy Laboratories, ” ORNL/ Geological Survey, ” Geological Survey circular EIS-144, November 1978. No. 737, 1976. 49, Shriner, C. R. and Peck, L. J. (eds.), “Water Re- 59. Baltzer, Bob, personal interview, August 1979. source Management, Planning and Policy Models 60. Carrigan, Hadley, personal interview, August in Department of Energy Laboratories, Novem- 1979. ber 1978. 61. Faust, Charles R. and Mercer, James W., “Finite- Difference Model of Two-Dimensional Single- and Department of the Interior Two-Phase Heat Transport in a Porous Medium —version 1, U.S. Geological Survey report Bureau of Land Management 77-234, 1977. 62. Federal Interagency Work Group on Water Qual- 50. Bureau of Land Management, ‘ ‘Water Resource ity Data Needs for Small Watersheds, ‘‘Water Modeling in the Bureau of Land Management, Quality Data Needs for Small Watersheds: Sur- personal correspondence, 1979. face Water Data, Draft, ’ August 1978. 63, Grove, David B., ‘ ‘Ion Exchange Reactions Im- Bureau of Mines portant in Groundwater Quality Models, ” sym- 51. Bloomsburg, G. L. and Wells, R. D., “Seepage posium proceedings, Advances in Groundwater Through Partially Saturated Shale Wastes: Final Hydrology, 1976. Report, contract No. H0252965, September 64. Jackman, Alan P. and Yotshkura, Nobuhiro, 1978. “Thermal Loading of Natural Streams, ” U.S. 52. Bureau of Mines, ‘ ‘Response to OTA Question- Geological Survey professional paper 991, 1977. naire: Task Force on Water Resource Modeling, 65. Jennings, Marshall E. and Yotshkura, Nobuhiro, personal correspondence, November 1979. “Status of Surface-Water Modeling in the U.S. 53. Hittman Associates, Inc., “Monitoring and Mod- Geological Survey, ’ Geological Survey circular eling of Shallow Groundwater Systems in the Pow- No. 809, 1979. der River Basin: Second Annual Technical Re- 66. Konikow, Leonard F., “Modeling Chloride port, ” No. H-D0166-78-757F, February 1979. Movement in the Alluvial Aquifer at the Rocky Mountain Arsenal, Colorado, ” U.S. Geological Office of Water Research and Technology Survey water supply paper 2044, 1977. 67. Konikow, L. F. and Bredehoeft, J. D., “Com- 54. Reefs, Theodore G., ‘ ‘Response to OTA Ques- puter Model of Two-Dimensional Solute Trans- tionnaire: Task Force on Water Resource Model- port and Dispersion in Ground Water, USGS ing, ” personal communication, October 1979. book 7, ch. 2, 1978. 190 ● Use of Models for Water Resources Management, Planning, and Policy

68. Konikow, Leonard F., and Bredehoeft, John D., Independent Agencies “Modeling Flow and Chemical Quality Changes in an Irrigated Stream-Aquifer System, Water Council on Environmental Quality Resources Research, vol. 10, No. 3, June 1974. 69. Laird, L. B., “Response to OTA Questionnaire: 80 Buffington, J. D., Milask, L. J., “An Overview Task Force on Water Resource Modeling in the of the UPGRADE Data Analysis System. Federal Agencies, ” personal correspondence, 81 CEQ Executive Summary, response for OTA October 1979. Water Resources Workshop. 70. Larson, Steve, personal interview, August 1979. 82 CE~ “ ‘Strawman’ Responses to Objectives of 71. McKenzie, Stuart W., et al., “Steady-State Dis- the OTA Task Force on Water Resourses Model- solved Oxygen Model of the Willamette River, ing, “ Oct. 24-25, 1979. Oregon, ” U.S. Geological Survey circular 715-J, 1979. EPA: Office of Research and Development 72. Plummer, L. Niel, et al., ‘‘ WATEQF-A 83. Office of Research and Development, “Response FORTRAN IV Version of WATER, A Computer to OTA Questionnaire: Task Force on Water Re- Program for Calculating Chemical Equilibrium of source Modeling in Federal Agencies, personal Natural Waters, ” USGS, Water Resources Inves- correspondence, October 1979. tigations 76-13, September 1976. 84. Richardson, W. L., and Thomas. N. A.. “A ‘‘Documentation of Finite-Dif- 73, Trescott, Peter C., Review of EPA’s Great Lakes Modeling ‘Pro- ference Model for Simulation of Three-Dimension- gram, ‘‘ in Proceedings of the EPA Conference on al Ground-Water Flow, ” U.S. Geological Survey Environmental Modeling and Simulation, W. R. report 75-438, September 1975. Ott (cd.), report No., EPA-600/9-76-106 (Cincin- 74. Rickert, David A., and Hines, Walter G., “River nati, Ohio: Environmental Protection Agency, Quality Assessment: Implications of a Prototype 1976). Project, ’ Science, vol. 200, pp. 1113-1118, June 1978. EPA: Office of Toxic Substances 75. Trescott, Peter C., ‘‘Documentation of Finite-Dif- 85. Wood, B., “Response to OTA Questionnaire: ference Model for Simulation of Three-Dimension- Task Force on Water Resource Modeling in Fed- al Ground-Water Flow, U.S. Geological Survey eral Agencies, personal correspondence, October report 75-438, September 1975. 1979. 76 Trescott, P. C., Pinder, G. F., and Larson, S. P., 86 Survey and Analysis Division, Office of Toxic Sub- ‘‘Finite-Difference Model for Aquifer Simulation < stances, “Response to OTA Questionnaire: Task in Two Dimensions with Results of Numerical Ex- Force on Water Resource Modeling in Federal pediments, ” ch. 1, book 7 of Techniques of Agencies, personal correspondence, October Water-Resources Investigations of the U.S. Geo- 1979. logical Survey. 87. Zweig, G., “Response to OTA Questionnaire: 77. U.S. Geological Survey, “Computer Programs for Task Force on Water Resource Modeling in Fed- Modeling Flow and Water Quality of Surface eral Agencies, personal correspondence, October Water Systems, ” September 1978. 1979.

Bureau of Reclamation EPA: Office of Water Planning and Standards 78. Bureau of Reclamation, ‘‘Response to OTA Ques- 88. Athway, D., and Somers, P., staff, Urban Runoff tionnaire: Task Force on Water Resource Model- Program, Implementation Branch, Water Plan- ing, ” personal communication, November 1979. ning Division, Office of Water Planning and 79. Bureau of Reclamation, “Response to OTA Ques- Standards, EPA, personal interview, Aug. 17, tionnaire: Task Force on Water Resource Model- 1979. ing in Federal Agencies, personal correspond- 89. Cogger, B., “Response to OTA Questionnaire: ence, October 1979; Bureau of Reclamation, Bu- Task Force on Water Resource Modeling in Fed- reau of Reclamation Economic Assessment Model eral Agencies, personal correspondence, October (BREAM) Technical Description, January 1978; 1979. Ribbens, Richard W., Technical Description of 90. Dupuis, L., staff, Office of Analysis and Evalua- Return Flow Quality Simulation Model, Water tion, Water Planning and Standards, EPA, per- and Power Resources Service, January 1980. sonal interview, Aug. 17, 1979. App. B—Summary of Model Use by Individual Federal Agencies . 191

91. Ehreth, D., Callahan, M., Frederick, R., and No. EPA-600/3-79-028, prepared for Environmen- Slimak, M., staff, Water Quality Analysis Branch, tal Protection Agency, Athens, Ga., March 1976. Monitoring and Data Support Division, Office of 102. Taylor, P. L., “STORET: A Data Base for Water Planning and Standards, EPA, personal in- Models, ‘‘ in Workshop on Verification of Water terview, Aug. 17, 1979. Quality Models, report No. EPA-600/9-80-016, 92. Myers, C., staff, Implementation Branch, Water prepared for Environmental Protection Agency, Planning Division, Office of Water Planning and Athens, Ga., April 1980. Standards, EPA, personal interview, Aug. 17, 103 True, H. A., ‘ ‘Planning Models for Non-Point 1979. Runoff Assessment, in Proceedings of the EPA 93 Office of Analysis and Evaluation, “Response to Conference on Environmental Modeling and Sim- OTA Questionnaire: Task Force on Water Re- ulation, W. R. Ott, (cd.), report No. EPA-600/ source Modeling in Federal Agencies, personal 9-76-106 (Cincinnati, Ohio: Environmental Pro- correspondence, October 1979. tection Agency, 1976). 94. Stuart, T., Chief, Monitoring Branch, Office of 104 Versar, Inc., ‘‘ Environmental Assessment of Pri- Water Planning and Standards, EPA, personal in- ority Pollutants: A Review of Evaluative Models terview, Aug. 17, 1979. in Assessing the Fate of Pollutants, Final Report, 95. Swader, F., staff, Agricultural Runoff Program, contract No. 68-01-3852, prepared for Environ- Implementation Branch, Water Planning Division, mental Protection Agency, Washington, D.C. Office of Water Planning and Standards, EPA, February 1979. personal interview, Aug. 22, 1979. 96 Water Quality Analysis Branch, “Response to National Science Foundation OTA Qestionnaire:” Task Force on Water Re- source Modeling in Federal Agencies, personal 105. Ezra, A. A., “Executive Summary and ‘Straw- correspondence, October 1979. man’ Responses to Objectives of the OTA Task Force on Water Resource Modeling, ’ Oct. 24-25, EPA: General References 1979.

97. Beckers, C. V., Parker, P. E., Marshall, R. N., Water Resources Council and Chamberlain, S. G., ‘‘ RECEIV-11, A Gener- alized Dynamic Planning Model for Water Quality 106. Walker, Lewis D., Water Supply Adequacy Anal- Management, in Proceedings of the EPA Confer- ysis Model, for the OTA Task Force on Water Re- ence on Environmental Modeling and Simulation, source Modeling in the Federal Agencies, Oct. W. R. Ott (cd.), report No. EPA-600/9-76-100 24-25, 1979. (Cincinnati, Ohio: Environmental Protection Agency, 1976). General References 98< Environmental Protection Agency, ‘‘A Statistical Method for the Assessment of Urban Storm- 107. Brandstetter, A. G., ‘ ‘Assessment of Mathematical water, report No. EPA 440/3-79-023, prepared Models for Storm and Combined Sewer Manage- for Environmental Protection Agency, Washing- ment, report No. EPA-600/2-76- 175a, prepared ton, D. C., May 1979. for Environmental Protection Agency, Cincinnati, 99. Falco, J. W., and Mulkey, L. A., “Modeling the Ohio, August 1976. Effect of Pesticide Loading on Riverine Ecosys- 108. Bugliarello, G., and Gunther, F. C., Devel- tems, ‘‘ in Proceeding-s of the EPA Conference on opments in Water Science I: Computer Systems Environmental Modeling and Simulation, W. R. and Water Resources (New York: Elsevier Pub- Ott (cd.), report No. EPA-600/9-76- 106 (Cincin- lishing Co., 1974).

nati, Ohio: Environmental Protection Agency, 109 Chung, Sang Chu, et al., Computer programs in

1976). Water Resources, Minnesota University Water 100. Leytharn, K. M., and Johnson, R. C., “Water- Resources Research Center, November 1977. shed Erosion and Sediment Transport Model, 110, Grimsrud, G, Paul, et al., Evaluation of Water Report No. EPA-600/3-79-028, prepared for En- Quality Models: A Management Guide for Plan- vironmental Protection Agency, Athens, Ga. , ners (Palo Alto, Ca]if.: Systems Control Inc., March 1979. 1976). 101. Pechan, E. H., and Luken, R. A., “Watershed 111, Hinson, M. O., and Basta, D. J., “Analyzing Re- Erosion and Sediment Transport Model, ’ report ceiving Water Systems, ‘‘ in Analysis for Residuals 192 ● Use of Models for Water Resources Management, Planning, and Policy

—Environmental Quality Management: Analyz- ington, D. C., prepared for the Office of Research ing Natural Systems, Resources for the Future, and Development, U.S. Environmental Protection D. J. Basta and B. T. Bower (eds. ), Washington, Agency, December 1979. D. C,, prepared for the Office of Research and De- 114. Marks, David H., “Models in Water Resources, velopment, Environmental Protection Agency, in A Guide to Models in Governmental Planning December 1979. and Operations, EPA, August 1974. 112 Horton, M. L., et al., Analysis and Dissemination 115. U.S. Environmental Protection Agency, Environ- of Water Resources Information, South Dakota mental Modeling and Simulation, Washington, State University Water Resources Institute, 1979. D. C., Office of Research and Development and 113 Huber, W. C., and Heaney, J. P., “Analyzing Office of Planning and Management, EPA-600/ Residuals Generation and Discharges From Urban 9-76-016, 1976. and Nonurban Land Surfaces, in Analysis for 116, Viessman, W., Jr., Knapp, J. W., Lewis, G. L., Residuals-Environmental Quality Management: and Harbaugh, T. E., Introduction to Hydrology, Analyzing Natural Systems, Resources for the 2d ed. (New York: Harper & Row, 1977). Future. D. 1. Basta and B. T. Bower (eds.\. Wash- , “ \ / > App. B—Summary of Model Use by Individual Federal Agencies 193

ATTACHMENT II. —SURVEY OF FEDERAL AGENCY MODEL USE RELATED TO MAJOR LEGISLATION

July 14, 1980

CONGRESS OF THE UNITED STATES Office of Technology Assessment Washington, D C 20510

7. .

3. 194 . Use of Models for Water Resources Management, Planning, and policy

? . . ——————.——pro~rarn T f t 1 e and l,e~ is la t ive—.— Autbor ~ za ——t ion

Fi 11 in the proqram t i tle a t the top of eacb quest i onna ire . Provide the author i za t ion i f i t is not on the “a ter ?ro~ram Checklist or otber than authorization 1 istecl .

3. r~~plete—- the O~]est—.—>.—_—.—.-–?.- i onna ire (s)

A part ia 1 example quest ionna ire is c iven bel ow:

LeCi slat i ve Author 5 za t i on - Puhl ic law Q5-? 17

T’elevant qec t ion of Specific Purpose Law, Rule, Renul a t ion T

En fore e Power Plant Sect i on 316 t enp. mode 1s ~e~u- S i t infi 1!SP and l!n ECW lat ions, St an[la rcls, Cu ide 1 ines

4. ———————.4c!cI i t i ona 1 Comments - Any add i t i o na 1 c omnc n ts may be wr i t t e n o n the hack of the Tncl i vidual Pro~ram (?uest i onna i res.

If yotl have any quest ions ahout the survey, pl ease do not hesi tatc to cal 1 Robert Friedman, Project Director, a t ( 2n? ) 2?4-7031 .

?1 ease ma i 1 the compl e ted !.!a ter Vropram Checkl i st -—and Intlividual l’roflram Questionnaire(s) to:

IX. Rot~ert ~~. Frje~man Project Director Office of TechnoloFv Assessment U.S. ConRress IIashinpton, ~.C. ?(-151~ —

App. B—Summary of Model Use by lndividual Federal Agencies ● 195

PART I : WATER PROGRAM CHECKLIST -. Co I umn Lo 1 umn One Two

Program Involve- Model ment Use Section

FEDERAL WATER POLLUTION CONTROL ACT AMENDMENTS OF 1972 (AS AMENDED BY THE CLEAN WATER ACT OF 1977) [1 [1 Grants for pollution control programs S. 106 [1 [1 Mine water pollution control programs s. 107 [1 [1 Grants for construction of treatment works s. 201 [1 [1 Areawide waste treatment management S. 208 [1 [1 Basin planning S. 209 [1 [1 Water quality related effluent limitations S. 302 [1 [1 Water quality standards and implementation plans s. 303 L] [1 Toxic and pretreatment effluent standards s. 307 [1 [1 Oil and hazardous substances liability s. 311 [1 [1 Clean lakes s. 314 [1 [1 Thermal discharges and exemptions S. 316 [1 [1 Guidelines. . . permits for dredged or fill material s. 404 [1 [1 Disposal of sewage sludge s. 405

SAFE DRINKING WATER ACT [1 [1 Protection of underground sources of drinking water S. 1421 [1 [1 Special study and demonstration project grants for waste water reuse, reclamation and recycling processes s. 1444

TOXIC SUBSTANCES CONTROL ACT [1 [1 Testing of chemical substances and mixtures s. 4 [1 [1 Regulation of hazardous chemicals and mixtures S. 6 196 ● use of Mode/s for water Resources Management, planning, and Policy

Page 2

Column Column One Two

Program Involve- Model ment Use Section

RESOURCE CONSERVATION AND RECOVERY ACT [1 [1 Solid waste management guidelines S. 1008 [1 [1 Identification and listing of hazardous wastes s. 3001 [1 [1 Standards for owners and operators of hazardous waste treatment, storage and disposal facilities s. 3004 [1 [1 Consolidated permits for hazardous waste management facilities s. 3005 [1 [1 Grants for state resource recovery and conservation plans S. 4008 [1 [1 Full scale demonstration facilities grants S. 8004 [1 [1 Resource recovery systems and improved solid waste disposal facilities s. 8006

ENDANGERED SPECIES ACT [1 Minimizations of impacts of Federal activities modifying critical habitats s. 7

SURFACE MINING CONTROL AND RECLAMATION ACT [1 [1 Surface coal mine reclamation permitting S. 506 [1 [1 Environmental protection performance standards for surface coal mine reclamation s. 515

SOIL AND WATER RESOURCE CONSERVATION ACT OF 1977 [1 [1 Data collection about soil, water and related resources s. 5 [1 [1 Soil and water conservation programs S. 6

WATER RESOURCES PLANNING ACT [1 [1 Regional or river basin plans and programs and their relation to larger region requirements s. 102 [1 [1 Coordinating Federal water and related land resources programs and policies s. 102 App. B—Summary of Model Use by Individual Federal Agencies ● 197

Page 3

Column Column One Two

Program Involve- Model ment Use Section

COASTAL ZONE MANAGEMENT ACT [1 [1 State coastal zone land and water resources management program development and management grants s. 305

EXECUTIVE ORDER 11988 [1 [1 Floodplain management S. 2&3

FLOOD CONTROL ACT OF 1936 AND AMENDMENTS [1 [1 Flood control structures S. 1,2,3

WATER RESOURCES DEVELOPMENT ACT OF 1974 [1 [1 Nonstructural measures s. 73

FEDERAL RECLAMATION ACT OF 1902 AND AMENDMENTS [1 [1 Irrigation distribution systems (43 U.S.C. 421) [1 [1 Construction of small projects (43 U.S.C. 422)

OTHER ACT [1 [1 Other Programs s. [1 [1 s. [1 [1 s.

OTHER ACT [1 [1 Other Programs s. [1 [1 s. [1 [1 s. 198 . Use of Models for Water Resources Management, Planning, and Policy

PART I I : INDIVIDUAL PROGRAM QUESTIONNAIRE

Respondent PROGRAH — ———— (fill inonly one program on each Questionnaire) OffIce

Legislative authorization Agency ———— — (If not on OTA program list or other than authfi~zation listed on Water Program Checklist) Phone Number ● Relevant Section of Law, Actlvlties Specific Purposes for which Models are Used Rule, Regulation or Name of Model(s Agency Guideline or Generic Type — Program Planning and Scope

Promulgate Regulations, Set Standards, Oevelop Guidelines

Enforce Regulations, Standards, Guidelines

Comply with Regulations, Standards, Guidelines

Plan or Evaluate Projects, Activities

Allocate Plannlng or ConstructIon Funds

State or Local Advisory Assistance

Operation and Management

Other Program Activities

. Appendix C Summaries of Related Modeling Studies

This appendix summarizes five previously completed were provided in over 50 percent of surveyed modeling studies of model development, use, and dissemination— projects. Most of the projects were supported by grants, three conducted wholly within the United States, one with very infrequent specification of performance re- from Canada, and one international assessment. The quirements or desired detail and characteristics by the five were chosen for their currency and relevance to the funding agency. issues raised in this report, and largely corroborate OTA The survey identified two dimensions to the “ease findings regarding current modeling issues. They are: of use” problem: 1) decisionmaker understanding of 1. “Federally-Supported Mathematical Models: Sur- models, and 2) the adequacy of developer-supplied in- vey and Analysis, National Science Foundation structions for operating the model. Both developers and (NSF), 1974. agency personnel noted that policy makers frequently 2. “Ways to Improve Management of Federally- lack the training that would equip them to use models Funded Computerized Models, ” General Ac- appropriately. On the other hand, in about 75 percent counting Office (GAO), 1976. of the surveyed cases, the documentation supplied by 3. ‘‘A Study for Assessing Ways to Improve the Utili- the developer was considered inadequate to enable non- ty of Large-Scale Models, ’ National Bureau of project personnel to set up and run the model. The ma- Standards (NBS), 1978. jority of the documentation efforts failed to include user 4. “Survey of Environmental Management Simula- manuals, operating instructions, or computer programs. tion Models in Canada, ’ R. D. Miller. Use rates were found to be highest for models having 5. “SCOPE International Assessment Project on user manuals; these tended to be produced when fund- Groundwater Model Modeling” ing agencies specified desired model characteristics, and when funding was carried out under contracts rather 1. “Federally-Supported Mathematical than grants. Models: Survey and Analysis” (Fromm, Hamilton, & Hamilton) 2. “Ways to Improve Management of Federally-Funded Computerized Models” This survey was completed in 1974 by NSF. It surveyed a universe of over 650 models which addressed This 1976 survey conducted by GAO was based on some aspect of social decisionmaking, and which were responses to questionnaires regarding 519 federally used by or developed for nondefense Federal agencies. funded models developed and/or used in the U.S. Pacific Responses were received for 222 models, from over 230 Northwest. Fifty-seven of those models costing over project directors and 80 Federal agency monitors. $100,000 to develop were selected for detailed review— Respondents indicated that the most important con- and 33 of these were described by respondents as hav- straints limiting model utility were: 1 ) data availabil- ing encountered ‘‘major problems’ in development. ity, and 2) ease of use by nontechnicians. Responses also GAO characterized these problems as being due to: indicated a prevailing tendency for actual use of models . inadequate management planning (70 percent); to fall short of intended use. Policy-related model uses . inadequate management commitment (15 percent); appeared to have the greatest shortfall—between one- and third and two-thirds of the models failed to achieve their ● inadequate management coordination (15 percent). stated purposes with respect to direct application to pol- GAO found that model development problems tended icy problems. to result in models not being used once they are devel- Based on survey responses, staff attributed low policy oped, cost overruns for models, and prolonged develop- utilization rates for models primarily to lack of commu- ment time, The reasons most frequently given for model nication between model builders and potential policy- development problems were: 1) the unreliability of mod- . makers during model development, and secondarily to el results, 2) developers’ inability to obtain necessary policy makers’ limited capabilities to use models once data, and 3) users’ failure to allocate enough funds to they had been developed. The study found very little complete the model. GAO further outlined development interaction between developers and users during model problems stemming from deficiencies in management development— actual briefings were held in only 19 per- planning, commitment, and coordination: cent of the projects, and user agencies ran models and ● Problems attributable to inadequate management analyzed results in only 34 percent; written reports alone planning:

199 200 Use of Models for Water Resources Management, Planning, and Policy

— Management did not clearly define the problem computerized models, and coordinate with other Federal to be modeled; thus, the developer had to guess agencies to obtain advice regarding such standards and what had to be modeled. guidance. — The developer was not able to obtain the data needed to make the model function. 3. “A Study for Assessing Ways to Improve — Management allocated insufficient funds to the Utility of Large-Scale Models” complete the model. (S. I. Gass, Z. F. Landsdowne, — Management did not make workable provisions R. P. Harvey, and A. J. Lemonine) for updating the model for future use; thus, the model soon began to produce outdated informa- This study, completed in December 1978 for NBS, tion. surveyed a group of modelers selected for their recog- — Management did not make provisions for evalu- nized expertise and their interest in the modeling pro- ating the model. fession. Of 57 modelers who were requested to partici- — Management did not clarify documentation re- pate, 39 responded, yielding the following cross-section quirements for the model. As a result, only the of affiliations and expertise: developer understood how it worked and the re- Affiliation Expertise University 8 lationship maintained by the variables incor- Analytic ...... 19 Not-for-profi[ ...... 8 Simulation ...... 12 porated into it. Profit . . . . . 9 Economics . . . . . 9 ● Problems attributable to inadequate management Government ...... * commitment: Total ...... 39 Total ...... ~ — Management did not actively participate in These participants, responding to propositions and planning of the model. Thus, the model did not statements in 18 model improvement area categories, clearly reflect their needs. gave highest priority to proposals to clarify the relation- — Management did not understand computer ship between model developer and user, and increase modeling techniques and applications. Conse- the interaction between them. Strongest support was quently, they could not effectively use informa- voiced for such specific proposals as: tion obtained from the models. 1. Model developers should specify a documenta- ● Problems attributable to inadequate management tion plan in their contract, detailing the documents coordination: to be produced, the resources allocated, and per- — Management did not monitor the model devel- sonnel responsibilities. opment effort on a cent continuous basis. Thus, 2. The Federal Government should establish a flexi- management allowed development efforts to ble set of model documentation guidelines that can continue after they should have been termi- be used by model developers and sponsors to create nated. a project’s documentation plan. — Managers did not coordinate the development 3. Requests for proposals (RFPs) should indicate the effort with the developer. As a result, the model ultimate user of the model, and require meetings was developed without reasonable assurance between model developers and users to aid in de- that it would meet user needs. signing models to meet user requirements. Two major solutions for these problems were pro- 4 Model developers should be required to prepare posed in the GAO report: First, the use of a phased ap- verification and validation test plans, report results proach to model development, requiring the funding of the tests, and describe their implications for fu- agency to review projects and decide whether to con- ture use of their models. tinue development at the end of each of five stages: 5. Model forums should be established by profession- 1) problem definition, 2) preliminary design, 3) detail al organizations, industrial groups, and-the Feder- design, 4) evaluation, and 5) maintenance. This sug- al Government. gested procedure is seen as promoting a more thorough Participants also indicated strong support for coordi- early investigation of the nature of the problem and of nated model development and data collection. They sup- possible solution methods, as well as providing a method ported mandatory data availability and costing assess- of controlling commitments to modeling efforts. ments prior to the issuance of an RFP for a model, and GAO’s second proposal was that the Department of requirements for parallel data collection efforts to be Commerce and the General Services Administration, specified in the ‘ ‘scope of work ‘‘ if necessary data are using their respective authorities under the Brooks Act not already available. (Public Law 89-306), formulate Government-wide Moderate support was also expressed for: 1) requir- standards and guidance on developing and procuring ing greater specificity in the RFP statement of work, App. C—Summaries of Related Modeling Studies ● 201

including explicit statements of model scope and objec- ● model purpose and difficulties encountered during tives; 2) Federal exploration of phased management ap- the project. Where models were constructed pri- proaches to model development; and 3) requiring all marily for research purposes, lack of understanding model development contracts to address the issue of user of mechanisms, and lack of available data, were training. most often cited as problems; where models were Participants strongly disapproved of centralized Gov- intended for policy recommendations, lack of user ernment-sponsored review and analysis relating to mod- credibility was the most frequently named problem. els, specifically rejecting model clearinghouses; a model testing, verification, and validation center; and a Gov- ernment modeling research center. 5. “SCOPE International Assessment Project on Groundwater Model Modeling’ 4. “Survey of Environmental Management Simulation Models in Canada” The SCOPE project was carried out between 1975 (R. D. Miller) and 1977, primarily through surveys of two groups: 1) active model developers, and 2) those active in Simulation modelers in Canada who were involved applying models to management problems. Reports on with developing environmental management models approximately 250 models were submitted in response were requested to complete questionnaires regarding the to the project survey. models they had developed. Questions were directed to- The purpose of the assessment was to provide guid- ward five general areas: ance on measures for improving the utility of models 1. purpose of the model, including the audience to in ground water management. Four major problem which it was directed; areas were identified during the course of the project, 2. degree of success, including implementation of the and were ranked by project staff and an international model and its use in decisionmaking; steering committee in the following order of importance: 3. problems encountered during model development 1. accessibility of models to users; and implementation; 2. communications between managers and technical 4. planning and managerial factors that might serve personnel; as predictors of success; and 3. inadequacies of data; and 5. technical details of how the simulation was car- 4. inadequacies of modeling. ried out. The survey found difficulties in gaining access to exist- The overall results of the survey suggest that the suring models to be the most serious impediment to effec- veyed model development projects suffered from lack tive use of models in ground water management. Major of involvement and meaningful contribution by deci- problems of accessibility revolve around the usability sionmakers in the early stages of model development. of model documentation, model distribution, adequate A lack of user credibility accorded to the model was re- training in the use of models, and user certification. ported only in cases where users had not been involved Project staff suggested that improvements in these areas in managing the project. In these cases, user credibil- would require shifts in the incentive structures of institu- ity was cited as a problem with far greater frequency tions, or even modifications to the institutions them- than the modeler’s willingness to help, suggesting that selves. Their primary recommendation involved estab- modelers neglect to involve decisionmakers more often lishing public agency requirements for adequate docu- than decisionmakers refuse to consider the advantages mentation as a prerequisite for funding any model devel- of developing models. opment effort. Specific correlations were found between: To improve communication between managers and perceived success and attempts to involve users at technical personnel, the study staff recommended meas- early stages of development, specifically by giving ures to increase interactive participation in problem def- system managers some voice in managing the simu- inition and model application, so that managers become lation project; directly involved in developing the models they commis- perceived success and preproject literature searches sion. Additional recommendations included designing or state-of-the-art surveys; model outputs to be easily understandable by nontechni- perceived success and intended audience. Cases cal personnel, and encouraging further development of where model output was to be used by technical management “decisionmaking” models. or research staff had a significantly better success Data-gathering recommendations stressed improved level than cases where model results were to be used methods for routine data collection, storage, and retriev- by policy formulation groups, or middle- or high- al, and sensitivity analysis as a method of determining level management; and the most critical data needs for modeling purposes.

. .- I .r{ - 11, Appendix D Additional References to Models and Modeling Studies

Surface Water Flow and 25. Irrigation Water Demand Models (57, 100) 26. Land Drainage Models (49, 57, 110, 114) Supply References 27 (Conduit Capacity Models ( 11) Table of Model Types (with 28. 1Pipe Network Models (56, 113) 1Regional Water Use Relationships (30, 42) reference numbers) 29. 30< Annual Use Generation Models (17) General (50, 54, 66, 75, 82, 86, 112) 31, Plant Water Use Models (6, 13, 14, 35, 38, 55, 76, 1. Watershed Soil/Water Process Models (5, 7, 9, 16, 77, 83, 107) 18, 19, 23, 40, 41, 43, 53, 57, 59, 61, 88, 91, 95, 32, System Water Need Models (56) 97, 98, 104, 108, 116, 117, 118, 119) 2. Snow Accumulation and Melt Models (1, 2, 3, 9, References 16, 23, 40, 41, 43, 53, 59, 61, 98, 106, 118, 119) 3. Baseflow Models (5, 7, 9, 16, 19, 23, 34, 40, 41, 1. Anderson, E. A., ‘ ‘The Synthesis of Continuous 43, 52, 53, 57, 59, 61, 88, 98, 117, 118, 119) Snowmelt Runoff Hydrography on a Digital Com- 4. Channel Routing Models (5, 9, 16, 18, 19, 28, 40, puter, technical report 36, Department of Civil 41, 43, 47, 74, 91, 95, 97, 98, 104, 108, 119) Engineering, Stanford University, Stanford, 5. Lake and Reservoir Routing Models (19, 43, 47, Calif., 1964. 57, 97, 98) 2. , “National Weather Service River Fore- 6. Flood Formulae (24, 32, 37, 39,62, 73,80,93, 108) cast System: Snow Accumulation and Ablation 7. Regional Flood Equations (24, 26, 48, 62, 64, 73, Model, ” NOAA technical memorandum, NWS 87, 92, 115) HYDRO- 17, Department of Commerce, Silver 8. Regional Flood Simulation Models (24, 45, 62, 65, Spring, Md., 1973. 125) 3 > “A Joint Energy and Mass Balance Mod- 9. Flow Frequency Models (73, 78, 85) el of a Snow Cover, NOAA technical report, 10. Evapotranspiration Models (5, 9, 16, 18, 19, 23, NWS 19, Department of Commerce, Silver 31, 40, 41, 43, 53, 57, 58, 59, 60, 61, 76, 77, 83, Spring, Md., 1976. 91, 96, 97, 98, 107, 116, 117, 118, 119) 4. Beer, C. E., and Johnson, H. P., “Factors Related 11. Unit Hydrography Models (22, 24, 39, 62, 94, 108) to Gully Growth in the Deep Loess Area of West- 12. Dam Failure Models (5, 10, 44) ern Iowa, ” Department of Agriculture, miscellane- 13. Reservoir Water Accounting Models (9, 57, 98) ous publication 970, 1965, pp. 37-43. 14. Annual Data Generation Models (27, 67,68,69, 79) 5. Betson, R. P., ‘‘A Continuous Daily Streamflow 15. Regional Data Generation Models (20, 26, 36, 51, Model, TVA research paper No. 8, Knoxville, 64, 70, 79, 87, 111) Term., 1972. 16. Reservoir Sedimentation Models (8, 15, 57, 98) 6. Blaney, H. F., and Griddle, W. D., “Determin- 17. Ice Formation and Breakup Models (21, 25, 33, 71, ing Water Requirements in Irrigated Areas From 72, 81, 89, 102, 103, 120) Climatological and Irrigation Data, ” Department 18. Freezing and Breakup Formulae (12, 21, 25, 33, 72, of Agriculture, Soil Conservation Service, TP-96, 81, 89, 102, 103, 120) 1950. 19. Plot Size Soil/Water Process Models (29, 31, 53, 7. Bowles, D. S., and Riley, J. P., “Low Flow Mod- 57, 58, 59, 60, 61, 88, 95, 96, 108) eling in Small Steep Watersheds, Journal of 20. Plot Snow Accumulation and Melt Models (31, 53, the Hydraulics Division, proceedings of ASCE 59, 60, 61, 96) 102( HY9):1225- 1239, 1976. 21. Bank Sloughing Models (109) 8. Brune, G. M., ‘ ‘Trap Efficiency of Reservoirs, 22. Flood Inundation Models (46) Transactions of the American Geophysical Union, 23. Channel Erosion and Deposition Models (4, 84, 90, 34(3):407-418, 1953. 101, 105) 9. Burnash, R. J. C., Ferrall, R. L., and McGuire, 24. Channel Geometry Equations (63, 99) R. A., “A Generalized Streamflow Simulation

202 App. D—Additjonal References to Models and Modeling Studies ● 203

System: Conceptual Modeling for Digital Comput- cumulation and Melt Process in a Snowpack, ers, unnumbered publication, California Depart- Utah Water Research Laboratory Publication ment of Water Resources, 1973. PRWG65-1, 1971. 10 Chen, C-L, and Armbruster, J. T., Darn-Break 24 Eychaner, J. H., “Estimating Runoff Volumes Wave Model: Formulation and Verification, pro- and Flood Hydrography in the Colorado River Ba- ceedings of ASCE, 106( HY5):747-768, 1980. sin, Southern Utah, U.S. Geological Survey Wa- 11. Chow, V. T., Open Channel Hydraulics (New ter Resources Investigations 76-102, 1976. York: McGraw-Hill, 1959). 25. Ficke, E, R., and Ficke, J. F., “Ice on Rivers and 12. Handbook of Applied Hydrology (New Lakes: A Bibliographic Essay, ” U.S. Geological York: McGraw-Hill, 1964). Survey Water Resources Investigations, 1977. 13. Christensen, J. E., ‘ ‘Pan Evaporation and Evapo- 26. Fields, F. K., ‘‘Estimating Strearnflow Character- transpiration From Climatic Data, proceedings istics for Streams in Utah Using Selected Channel- of ASCE, 94( IR2):243 .265, 1968. Geometry Parameters, ” U.S. Geological Survey 14 Christensen, J. E., and Hargreaves, G. H., “Irri- Water Resources Investigations 34-71, NTIS gation Requirements From Evaporation, Inter- PB-241 541, 1975. national Commission on Irrigation and Drainage, 27 Fiering, M. B., and Jackson, B. B., Synthetic Seventh Congress, 25.569-23.596, 1970. Streamflows, Water Resources Monograph 1, 15 Churchill, M. A., “Discussion of ‘Analysis and American Geophysical Union, Washington, D. C., Use of Reservoir Sedimentation Data, by L. C. 1971. Gottschalk, proceedings of the Federal Inter- 28. Fread, D. L., ‘ ‘Technique for Implicit Dynamic agency Sedimentation Conference, Denver, CO1O., Routing in Rivers and Tributaries, ” Water Re- 1945, pp. 139-140 (published by Department of the sources Research 9(4):918-926, 1973. Interior, Bureau of Reclamation, Denver). 29. Gifford, G. F., and Hawkins, R. H., “Determinis- 16. Crawford, N. H., and Linsley, R. K., “Digital tic Hydrologic Modeling of Grazing System Im- Simulation in Hydrology: Stanford Watershed pacts on Infdtration Rates, ” Water Resources Bul- Model IV, ” technical report 39, Department of letin 15(4):924-934, 1979. Civil Engineering, Stanford University, Stanford, 30. Gleason, G. B., “Consumptive Use in Municipal Calif., 1966. and Industrial Areas, proceedings of ASCE 77, 17. Cruz, S-L, and Yevjevich, V., “Stochastic Struc- separate No. 99, 1951. ture of Water Use Time Series, Colorado State 31. Goldstein, R. A., Mankin, J. B., and Luxmore, University hydrology paper No. 52, 1972. R. J., “Documentation of PROSPER: A Model 18. Dawdy, D. R., Lichty, R. W., and Bergman, of Atmosphere-Soil-Plant Water Flow, EDFB- J. M., ‘‘A Rainfall-Runoff Simulation Model for IBP-73-9, Oak Ridge National Laboratory, Oak Estimation of Flood Peaks for Small Drainage Ridge, Term., 1974. Basins, U.S. Geological Survey professional 32. Grunsky, C. E., “Rain and Runoff Near San paper 506-6 (Washington, D. C.: U.S. Govern- Francisco, California, ” transactions of ASCE, ment Printing Office, 1972). 1090, 1908. 19. Dawdy, D. R., Schaake, Jr., J. C., and Alley, 33. H. G. Acres, Ltd, “Review of Current Ice Tech- W. M., “Distributed Routing Rainfall-Runoff nology and Evaluation of Research Priorities, Model, ” U.S. Geological Survey Water Resources report to Inland Waters Branch, 105, Environment Investigations 78-90, 1978. Canada, 1971. 20. DeWalle, D. R., and Rango, A., “Water Re- 34. Hall, F. R., “Base-Flow Recessions: A Review. sources Applications of Stream Channel Charac- Water Resources Research, ” 4(5):973-983, 1968. teristics on Small Forested Basins, Water Re- 35. Hargreaves, G. H., ‘ ‘Consumptive Use Derived sources Investigations 78-90, 1972. From Evaporation Pan Data, proceedings of 21 Dilley, J. F., “Lake Ontario Ice Modeling, ” ASCE, 94( IR1):97-105, 1968. IFYGL Phase 3, General Electric Co., Philadel- 36. Hedman, E. R., “Mean Annual Runoff as phia, Pa., NTIS PB-264 998, 1976. Related to Channel Geometry of Selected Streams

22. Dooge,, J. C. I., ‘ ‘Linear Theory of Hydrologic in California, U.S. Geological Survey Water Systems, ’ Department of Agriculture Technical Supply report 1999-E (Washington, D. C.: U.S. Bulletin 1468 (Washington, D. C.: U.S. Govern- Government Printing Office, 1970). ment Printing Office, 1973). 37 Helvey, J. D., “Interception by Eastern White 23. Eggleston, K. O., Israelsen, E. K., and Riley, Pine, Water Resources Research, 3(3):723-729, J. P., ‘ ‘Hybrid Computer Simulation of the Ac- 1967. 204 Use of Models for Water Resources Management, Planning, and Policy

38. Hendricks, D. W., and Hansen, V. E., “Mechan- Survey, ” U.S. Geological Survey circular 809, ics of Evapotranspiration, transactions of ASCE, 1979. 128 (111):422-443, 1962. 55. Jensen, M. E., and Haise, H. R., ‘ ‘Estimating 39. Hewlett, J. D., Cunningham, G. B., and Troen- Evapotranspiration From Solar Radiation, pro- dle, C. A., “Predicting Stormflow and Peakflow ceedings of ASCE, 89( IR4): 15-41, 1963. From Small Basins in Humid Areas by the R- 56. Jeppson, R. W., Analysis of Flows in Pipe Net- Index Method, ” Water Resources Bulletin, 13(2): works, Ann Arbor Science, 1976. 231-253, 1977. 57. Knisel, W. G. (cd.), CREAMS: A Field Scale 40. Holtan, H. N., and Lopez, N. C., “USDAHL-70 Model for Chemicals, Runoff and Erosion From Model of Watershed Hydrology, ” U.S. Depart- Agricultural Management Systems, Department ment of Agriculture Technical Bulletin 1435, 1971. of Agriculture Conservation Research Report 26, 41. , ‘‘USDAHL-73 Revised Model of Water- 1980. shed Hydrology, Department of Agriculture 58. Larson, N. M., and Reeves, M., “Analytic Anal- Plant Physiological Institute report 1, 1973. ysis of Soil-Moisture and Trace Contaminant 42. Hughes, T. C., and Gross, R., “Domestic Water Transport, ” Oak Ridge National Laboratory re- Demand in Utah. Utah Water Research Labora- port ORNL/NSF/EATC-12, undated. tory report UWRL/P-79/04, 1979. 59. Leaf, C. F., and Alexander, R. R., “Simulating 43. Hydrocomp, Inc., “Hydrocomp Simulation Pro- Timber Yields and Hydrologic Impacts Resulting graming Operations Manual, ” Hydrocomp, Inc., From Timber Harvest on Subalpine Watersheds, Palo Alto, Calif., 1969. 1975. 44. “FULEQ Full Equations Hydraulics 60. Leaf, C. F., and Brink, G. E., “Computer Simu- Dam Failure, ” Palo Alto, Calif., 1976. lation of Snowmelt Within a Colorado Subalpine 45. “Planning and Modeling in Urban Water Watershed, Department of Agriculture Forest Manag~ment, Palo Alto, Calif., 1978. Service research paper RM-99, 1973. 46, Hydrologic Engineering Center, ‘‘HEC-2, Water 61. 7 “Hydrologic Simulation Model of Colo- Surface Profiles: User’s Manual, ” U.S. Army rado Subalpine Forest, Department of Agricul- Corps of Engineers, Davis, Calif., 1972. ture Forest Service research paper RM-107, 1973. 47. ‘‘HEC-5C, Reservoir System Operation 62. Lee, B. H., Reich, B. M., Rachford, T. M., and for Flood Control and Conservation, U.S. Army Aron, G., “Flood Hydrograph Synthesis for Rural Corps of Engineers, Davis, Calif., 1975. Pennsylvania Watersheds, ” Department of Civil 48. Hydrology Committee, Water Resources Council, Engineering, Pennsylvania State University, 1974. ‘ ‘Guidelines for Determining Flood Flow Frequen- 63. Leopold, L. B., and Maddock, T. G., “The Hy- cy, ” bulletin 17, 1976. draulic Geometry of Stream Channels and Some 49. International Institute for Land Reclamation and Physiographic Implications, ” U.S. Geological Sur- Improvement, Drainage Principles and Applica- vey professional paper 252, 1953. tions, publication No. 16, 4 vols., Wajeninen, 64. Lowham, H. W., “Techniques for Estimating Netherlands, 1972. Flow Characteristics of Wyoming Streams, U.S. 50 James, D. E. (cd.), U.S. National Report to the Geological Survey Water Resources Investigations IUGG, American Geophysical Union, Washing- 76-112, 1976. ton, D. C., 1979. 65. Lumb, A. M., and James, L. D., “Runoff Files 51 James, L. D., Bowles, D. S., James, W. R., and for Flood Hydrography Simulation, proceedings Canfield, R. V., Estimation of Water Surface Ele- of ASCE, 102 (HY1O): 1515-1531, 1976. vation Probabilities and Associated Damages for 66. McCuen, R. H., Rawls, W. J., Fisher, G. T., and the Great Salt Lake, Utah Water Research Lab- Powell, R. L., ‘ ‘Flood Flow Frequency for Un- oratory publication UWRL/P-79/03, 1979. gaged Watersheds: A Literature Evaluation, De- 52. James, L. D., and Thompson, W. O., ‘‘ Least partment of Agriculture, Agriculture Research Squares Estimation of Constants in a Linear Re- Service, ARS-NE-86, 1977. cession Model, ” Water Resources Research, 6(4): 67. Mandelbrat, B. B., ‘‘A Fast Fractional Gaussian 1062-1069, 1970. Noise Generator, Water Resources Research, 53. Jaynes, R. A., ‘‘A Hydrologic Model of Aspen- 7(3):543-553, 1971. Conifer Succession in the Western United States. ” 68. “Broken Line Process Defined as an Ap- Department of Agriculture Forest Service research proxim~tion to Fractional Noise, Water Re- paper INT213, 1978. sources Research, 8(5): 1354-1356, 1972. 54. Jennings, M. E., and Yotsukura, N., ‘‘ Status of 69. Mejia, J. M., Rodriguez-Itunbe, 1., and Dawdy, Surface-Water Modeling in the U.S. Geological D. R., ‘‘Streamflow Simulation 2: The Broken App. D—Additional References to Models and Modeling Studies ● 205

Line Process as a Potential Model for Hydrologic riculture Forest Service, Region 1, Missoula, Simulation, Water Resources Research, 8(4): Mont., 1975. 931-941, 1972. 85. Rae, D. V., ‘ ‘Log Pearson Type 3 Distribution: 70. Mejia, J. M., and Rousselle, J., “Disaggregation A Generalized Evaluation, ” proceedings of ASCE, Models in Hydrology Revisited, ” Water Re- 106( HY5):853-872, 1980. sources Research, 12(2): 185-186, 1976. 86. Renard, K. G., Rawls, W. J., and Fogel, M. M., 71. Muller, A., ‘‘Frazil Ice Formation in Turbulent “Currently Available Models, ” ch. 13 in Hydro- Flow, ‘‘ report No. 214, Iowa Institute of Hydraulic logic Modeling of Small Watersheds, ASAE mono- Research, Iowa City, Iowa, 1978. graph, St. Joseph, Mich., 1980. 72. Muller, A., and Calkins, D. J., “Frazil Ice For- 87 Riggs, H. C., ‘‘Streamflow Characteristics From mation in Turbulent Flow, ” proceedings of IAHR Channel Size, ” proceedings of ASCE, 104( HY1): Symposium on Ice Problems, Lulea, Sweden, vol. 87-96, 1978. II: 219-234, 1978. 88 Riley, J. P., and Hawkins, R. H., “Hydrologic 73. National Environmental Research Council, Flood Modeling of Rangeland Watersheds, ” in Water- Studies Report, Volume I: Hydrological Studies, shed Management on Range and Forest Lands, London, England, 1975. proceedings of the Fifth Workshop of the United 74. Flood Studies Report, Volume II; Flood States/Australia Rangelands Panel, Boise, Idaho, Routing Studies, London, England, 1975. published by Utah Water Research Laboratory, 75. Nieber, J. L., Walter, M. F., and Black, R. D., 1975. ‘‘A Review and Analysis of Selected Hydrologic 89. Rogers, J. C., “Evacuation of Techniques for Modeling Concepts, OWRT completion report, Long Range Forecasting of Air Temperature and project No. A-061-NY, 1975. Ice Formation, NOAA technical memorandum 76. Nimah, M. N., and Hanks, R. J., “Model for ERL GLERL-8, 1976. Estimating Soil, Water, Plant, and Atmospheric 90. Rosgen, D. F., “Mass Wasting, ” ch. III in Interrelations, 1: Description and Sensitivity, ” WRENS: U.S. Forest Service Report to EPA, proceedings of SSSA, 37:522-527, 1973a. agreement EPA-IAG-D6-0060, Review Draft. 77. ‘ ‘Model for Estimating Soil, Water, 91. Ross, B. B., Shanholtz, V. O., Contractor, D. N., Plant, and Atmospheric Interrelations, 2: Field and Carr, J. C., ‘‘A Model for Evaluating the Ef- Test of Model, ” proceedings of SSSA, 37:528-532, fect of Land Uses on Flood Flows, ” bulletin 85, 1973b. Virginia Water Resources Research Center, 1975. 78. North, M., ‘ ‘Time Dependent Stochastic Model 92. Saah, A. D., et al., ‘ ‘Development of Regional Re- of Floods, ” proceedings of ASCE, 106(HY5):649- gression Equations for Solution of Certain Hydro- 665, 1980. logic Problems in and Adjacent to Santa Clara 79. O’Connell, P. E., “Stochastic Modeling of Long- County, ” Santa Clara Valley Water District, San Term Persistence in Streamflow Sequences, ” in- Jose, Calif., 1976. ternal report, Hydrology Section, Civil Engineer- 93. Sellars, W. D., Physical C)imato]ogy, University ing Department, Imperial College, London, 1974. of Chicago Press, 1965. 80. 01’ deKop, E. M., ‘ ‘On Evaporation From the 94. Sherman, L. K., ‘ ‘Stream-Flow From Rainfall by Surface of River Basins, Tr. IUr’ev Obs. Lenin- the Unit-Graph Method, Engineering News- grad, 1911 (cited in Sellars, 1965). Record, 108:501-505, 1932. 81. Osterkamp, T. E., ‘‘Frazil Ice Formation: A Re- 95. Simons, D. B., Li, R. M., and Stevens, M. A., view, proceedings of ASCE, 104( HY9): 1239- ‘ ‘Development of a Model for Predicting Water 1256, 1978. and Sediment Yield From Storms on Small Water- 82. Peck, E. L., Bochin, N. A., Kouzel, A., Lennox, sheds, Department of Agriculture Forest Service, D. H., and Sundblad, B. (eds. ), State of the Art Rocky Mountain Forest and Range Experiment in Transposable Watershed Models, proceedings Station, Flagstaff, Ariz., 1975. of Third Northern Research Basin Symposium 96. Solomon, R. M., Ffolliott, P. F., Baker, Jr., M. Workshop, International Hydrological Program, B., and Thompson, J. R., “Computer Simulation Quebec City, 1979. of Snowmelt, Department of Agriculture Forest 83. Penman, H. L., “Natural Evaporation From Service research paper RM-174, 1976. Open Water, Bare Soil, and Grass, ” proceedings 97 Spencer, D. W., and Alexander, T. W., “Tech- of Royal Society of London, Series A 193: 120-145, nique for Estimating the Magnitude and Frequen- 1948. cy of Floods in St. Louis County, Missouri, U.S. 84< Pfankuch, D. J., ‘ ‘Stream Reach Inventory and Geological Survey Water Resources Investigations Channel Stability Evaluation, ” Department of Ag- 78-139, 1978. 206 ● Use of Models for Water Resources Management, Planning, and Policy

98. Staff, Hydrologic Research Laboratory, “National 113. Wake, A., and Rumer, R. R., “Development of Weather Service River Forecast System, Forecast a Thermodynamic Model for Ice Regime in Lake Procedures, NOAA technical memorandum Erie, proceedings of IAHR Symposium on Ice NWS HYDRO-14 and HYDRO-17, Department Problems, Luela, Sweden, vol. II: 143-162, 1978. of Commerce, Silver Spring, Md., 1972. 114, Walker, W. R., ‘‘Identification and Initial Evalua- 99. Stall, J. B., and Fok, Y. S., “Hydraulic Geometry tion of Irrigation Return Flow Models, ” Irriga- of Illinois Streams, ’ University of Illinois Water tion Hydrology Co., Fort Collins, Colo., 1978. Resources Center research report 15, 1968. 115, Watt, W. E., “A Relation Between Peak Dis- 100. Stewart, J. I., et al., “Optimizing Crop Produc- charge and Maximum 24-Hour Flow for Rainfall tion Through Control of Water and Salinity Levels Floods, Journal of Hychdology, 14:285-292, 1971. in the Soil, Utah Water Research Laboratory 116, Williams, J. R., and LaSeur, W. V., ‘‘Water publication PRWG151-1, 1977. Yield Model Using SCS Curve Numbers, ” pro- 101 Swanson, J. F., and Swanston, D. N., “A Con- ceedings of ASCE, 102( HY9): 1241-1254, 1976. ceptual Model of Solid Mass Movement Surface 117< Wilson, T. V., and Ligon, J. T., “Prediction of Soil Erosion and Stream Channel Erosion Proc- Baseflow for Piedmont Watersheds, ” technical re- esses, ” Coniferous Forest Biome Erosion Model- port 80, Clemson University Water Resources Re- ing Group, biome report No. 72, 1973. search Institute, 1979. 102. Tatinclaux, J. C., ‘ ‘Equilibrium Thickness of Ice 118. Woodward, D. E., “Hydrologic and Watershed Jams,” proceedings of ASCE, 103( HY9):959-974, Modeling for Watershed Planning, ” transactions 1977. of ASAE, 99(3):582-584, 1973. 103. “River Ice Jam Models. ” proceedings of 119. World Meteorological Organization, ‘‘Intercom- IAHR symposium on Ice Problems, Luela, Swe- parison of Conceptual Models Used in Operational den, vol. 11:449-460, 1978. Hydrological Forecasting, ” WMO No. 429,

1044 Terstriep, M. L., and Stall, J. B., “The Illinois Geneva, 1975. Drainage Area Simulator, ILLUDAS, ” Illinois 120. Yen, B. C., and Pansic, N., “Surcharge of Sewer State Water Survey bulletin 58, 1974. Systems, Illinois Water Resources ‘Center re-

1054 Thompson, J. R., “Quantitative Effects of Water- search report 149, 1980. shed Variances on the Rate of Gully Head Ad- vancement, transactions of ASAE, 7(1):54-55, 1964. Surface Water Quality Model References 106. Thomsen, A. G., and Striffler, W. D., “Hydro- graphy Simulation With Spatially Distributed The following tables and figures are from: Input, ” presented at the American Geophysical D. J. Basta and B. T. Bower (eds. ), Analysis for Union fall meeting, San Francisco, Calif., 1979. Regional Residuals— Environmental Quality 107. Thornthwaite, C. W., ‘ ‘An Approach Toward a Management: AnaJyzing Natural Systems, Rational Classification of Climate, Geographical Resources for the Future Research Paper Review, 38(1):55-94, 1948. (Baltimore, Md.: Johns Hopkins University Press 108, USDA, Soil Conservation Service, National Engi- for Resources for the Future, 1982). neering Handbook, sec. 4, ‘‘Hydrology’ (Wash- Figure D-1 displays 14 of the most widely used sur- ington, D. C.: U.S. Government Printing Office, face water runoff models, and the types of problems each 1972). model is capable of analyzing. The following table (table 109. USDI, Bureau of Reclamation, “Design of Small D-1) lists and identifies the originator of over 40 sur- Dams, A Water Resources Technical Publica- face water runoff models, including the 14 from figure tion, sees. 135 to 139 (Washington, D. C.: U.S. D-1. Table D-1 is organized by the following categories: Government Printing Office, 1977). screening procedures, simplified computer models, con- 110. ‘‘A Guide to Integrated Plant, Soil and tinuous simulation models, and single event simulation Water ‘Relationships for Drainage of Irrigated models. The table includes those models that have Lands, ’ Drainage ManuaZ, Washington, D. C., received most extensive use (both private and govern- 1978. mental models) and less widely used models developed 111, Valencia, D., and Schaake, Jr., J. C., “Disaggre- by governmental agencies. gation Processes in Stochastic Hydrology, ” Water Figure D-2 displays 27 of the most widely used receiv- Resources Research, 9(3):580-585, 1973. ing water quality models and the types of water bodies 1124 Van Haveren, B. P., and Leaveslen, G. H., “Hy- and problems they address. Again, table D-2 follows drologic Modeling of Coal Lands, ’ Department with a more extensive list of models, concentrating on of Interior, Bureau of Land Management, Denver, those most widely used and/or developed by a Govern- Colo., 1979. ment agency. App. D—Additional References to Models and Modeling Studies . 207

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● ● 0 ● ● 00 ● 9 208 . Use of Models for Water Resources Management, Planning, and Policy

TABLE D-1 Commonly Used Surface Water Runoff Models

Model Name Commonly Used Acronym Originator

SCREENING PROCEDURES

Hydroscience Simplified Model --- Hydroscience, Inc., Westwood, N.J.

Storm Water Management Model, SWMM-Level I Dept. of Environmental Level I Engineering Science, University of Florida, Gainesville, Florida

Midwest Research Institute MM Midwest Research Institute, Loading Functions Kansas City, Missouri SIMPLIFIED COMPUTER

Rational Method -— ---

Los Angeles Hydrography Method --- City of Los Angeles, Los Angeles, California

Santa Barbara Urban Hydrography SBUH Santa Barbara County Flood Method Control and Water Conservation District, Santa Barbara, California

Environmental Pollution Assessment- EPARRB National Environmental Research Erosion, Sedimentation and Rural Center, Environmental Runoff Model ProtectIon Agency, Athens, Georgia

TVA Stormwater Model Division of Water Control Planning, Tennessee Valley Authority, Knoxville, Tennessee

Simplified Storm Water Managemnt Simplified SWMM Metcalf and Eddy, Inc., Model Palo Alto, California

CONTINUOUS SIMULATION

Stanford Watershed Model Variants

Stanford Watershed Model IV SUM-IV Department of Civil Engineering, Stanford University, Palo Alto, California App. D—Additional References to Models and Modeling Studies ● 209

TABLE D-1 (Continued) Commnlv Used Surface Water Runoff Models

Model Name Commonly Used Acronym Originator

Kentucky Watershed Model KWM University of Kentucky, Lexington, Kentucky

Self-Optimizing, Continuous OPSET University of Kentucky, Hydrologic Simulation Model Lexington, Kentucky

National Weather Service River NWSRFS Office of Hydrology, National Forecast System Weather Service, Silver Spring, Maryland

Sacramento Model --- National Weather Service River Forecast Center and State of California Dept. of Water Resources, Sacramento, California

TVA Daily Flow Model TVA Division of Water Control Planning, Tennessee Valley Authority, Knoxville, Tennessee

Hydrocomp Simulation Program HSP Hydrocomp, Inc., Palo Alto, California

Pesticide Transport and Runoff Pm Hydrocomp, Inc., Model Palo Alto, California

Agricultural Runoff Management ARM Hydrocomp, Inc., Model Palo Alto, California

Nonpoint Source Model NPS Hydrocomp, Inc., Palo Alto, California

Terrestrial Ecosystem Hydrology TEHM Oak Ridge National Laboratory, Model Oak Ridge, Tennessee

Other Continuous Simulation Models

Agricultural Chemical Transport ACTMO Agricultural Research Service, Model USDA, Beltsville, Maryland

Streamflow Synthesis and Reservoir SSARR North Pacific Division, Corps Regulation of Engineers, Portland, Oregon 210 ● Use of Models for Water Resources Management, Planning, and Policy

TABLE D-1 (Continued) Commnlv Used Surface Water Runoff Models

Model Name Commonly Used Acronym Originator

Conversational Streamflow Synthesis COSSARR North Pacific Division, Corps and Reservoir Regulation Program of Engineers, Portland, Oregon

Storage, Treatnusnt, Overflow, and STORM Hydrologic Engineering Center, Runoff Model Corps of Engineers, Davis, California

Quantity-Quality-Simulation Model QQS Dorsch Consult, Munich, Germany and Toronto, Ontario

MIT Catchment Model MITCAT Dept. of Civil Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts and Resource Analysis, Inc., Waltham, Massachusetts

SINGLE EVENT SIMULATION

U.S. Dept. of Agriculture USDAHL-74 Agricultural Research Service, Hydrological Laboratory Model USDA, Beltsville, Maryland

Problem Oriented Computer Language HYMo Agricultural Research Service, for Hydrologic Modeling USDA, Soil and Water Conservation Research Division, Riesel, Texas

Computer Program for Project TR-20 C-E-I-R, Inc., for Soil Formulation Hydrology Conservation Service, USDA, Washington, D. C.

Urban Hydrology for Small TR-55 Soil Conservation Service, Watersheds USDA, Washington, D. C.

Agricultural Runoff Model AGRUN Water Resources Engineers, Inc. Walnut Creek, California

U.S. Geological Survey Rainfall USGS U.S. Geological Survey, Runoff Model for Peak Flow Reston, Virginia Synthesis

Calcul des Reseaux D’assainissement CAREDAS SOGREAH, Grenoble, France (Calculation of Sewage Networks) (also New York, New York) App. D—Additional References to Models and Modeling Studies ● 211

TABLE D-1 (Continued) Commonly Used Surf ace Water Runoff Models

Model Name Commonly Used Acronym Originator

Chicago Hydrography Method City of Chicago Bureau of (also NERO) Engineering, Chicago, Illinois

Chicago Flow Simulation Program FSP Metropolitan Sanitary District of Greater Chicago, Chicago, Illinois

HEC-1 Flood Hydrography Package HEC-1 Hydrologic Engineering Center, Corps of Engineers, Davis California

Hydrography Volume Method HVM Dorsch Consult, Munich, Germany and Toronto, Ontario

Illinois Urban Drainage Area ILLUDAS Illinois State Water Survey, Simulator Urbana, Illinois

Road Research Laboratory Model RRL Transport and Road Research Laboratory, London, United Kingdom

Storm Water Management Model Metcalf and Eddy, Palo Alto, California; University of Florida, Gainesville, Florida; Water Resources Engineers, Walnut Creek, California

University of Cincinnati Urban UCUR Dept. of Civil Engineering, Runoff Model University of Cincinnati, Cincinnati, Ohio 212 . Use of Mode/s for Water Resources Management, Planning, and Policy

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— 5-3 Z* ● 00 ● 0 ● 0 ;~ ● ● *= 0000 0 u -

3 ● ● b= 000 000000 g ● 000 ● 000000 ;

— ● 00 ● 0 ● 00 ● 00 ● ● 000 ● 0 : ~ 0 ● 0000000 ● 00 ● 00 ● 0 ● 000 ● 0 : m ● 0000000 ● 00 ● 00 ● ● 00, ● 0 : 40 m m — L ● ● o . w k ● ● ● . 00 0 : z e i u < (a

● ● : —~ ● ● ● ● ● ● % 0000 00 0 0 : ● ● ● ~ ● ● ● — ● 000 ● ● 0 !? ● 0 ● ● 0 ● 0 ● .z ● ● ● ● ● ● g 0 0 0 * ● ● ● 0 ● ● $ ● ● 000 ● ● 0 — ● 0000 ● 0 ● ● 0 ● *2’ w ● 00000 ● 00 ● ● 00 ● 0 ● ● ● ● ● ii 0000000000 0000 0000 0 : ● ● 0 ● ● 4 z ● 0000 ● 000 ● 0 ● ● ● 0000 ● ● ● 0 ● 0000 ● 00000 ● 00 ● ● ● 00000 ● ● ● . i App. D—Additional References to Models and Modeling Studies 213

TABLE D-2 Commonly Used Receiving Water Quality Models

Model Name Commonly Used Acronym Originator

CHEMICAL REACT ION MODELS

Analytically Integrated

Streeter-Phelps Dissolved Indiana State Board of Health, Oxygen Equation Bloomington, Indiana

Lumped Parameter Nutrient Center for Inland Waters, Budget Model Canadian Fisheries Research Board, Burlington, Ontario

Long Term Phosphorus Balance Battelle Pacific Northwest Model Labs, Richland, Washington

Steady-State Stream Network SNSIM U.S. Environmental Protection Model Agency-Region II, New York, New York

Simplified Stream Model SSM Hydroscience, Inc., Westwood, New Jersey

Simplified Estuary Model SEM Hydroscience, Inc., Westwood, New Jersey

Numerically Integrated

Dissolved Oxygen Sag Model DOSAG-I Texas Water Development Board, Austin, Texas

Dissolved Oxygen Sag Model DOSAG-3 Water Resources Engineers, (revised version) Austin, Texas

SCI DOSAG Modification DOSCI Systems Control Inc., Palo Alto, California

Estuary Model Esool U.S. Environmental Protection Agency-Region II, New York, New York

Automatic Quality Model AUTO-QUAL U.S. Environmental Protection Agency, Washington, D. C. 214 . Use of Models for Water Resources Management, Planning, and Policy

TABLE D-2 (Continued) Commonly Used Receiving Water Quality Models

Model Name Commonly Used Acronym Originator

River Quality Model QUAL-I Texas Water Development Board, Austin, Texas

Dynamic Estuary Model DEM Water Resources Engineers, Walnut Creek, California

Tidal Temperature Model TTM U.S. Environmental Protection Agency, Pacific Northwest Laboratory, Corvallis, Oregon

Receiving Water Model RECEIV Water Resources Engineers, Module of SWMM Walnut Creek, California

Receiving Water Model RIVSCI Systems Control, Inc., (modification) Palo Alto, California

Receiving Water Model WRECEV Water Resources Engineers, (modification) Austin, Texas

Deep Reservoir Model DRM Water Resources Engineers, Walnut Creek, California

Lake Ecologic Model LAKSCI Systems Control, Inc., (modification of Deep Palo Alto, California Reservoir Model)

Reservoir Water Quality Model EPARES Water Resources Engineers, Austin, Texas

Hydrocomp Hydrologic Simulation HSP Hydrocomp, Inc., Program Palo Alto, California

Water Quality Feedback Model FEDBAK03 U.S. Environmental Protection (HA~3 modification) Agency-Region II, New York, New York

Coastal Circulation and CAFE/DISPER Ralph M. Parsons Laboratory, Dispersion Model Massachusetts Institute of Technology, Cambridge, Massachusetts

Estuary Water Quality Model EXPLORE-I Battelle Pacific Northwest Labs, Richland, Washington

Nutrient Accumulation Model SPLOTCH U.S. Environmental Protection Agency, Rochester, New York

Two-Diunsional Stream Mixing --- Water Resources Division, U.S. Model Geological Survey, Washington, D. C. App. D—Additional References to Models and Modeling Studies ● 215

TABLE D-2 (Continued) Commnly Used Receiving Water Quality Models

Model Name Commonly Used Acronym Originator

Outfall Plume Model PLUME U.S. Environmental Protection Agency, Pacific Northwest Laboratory, Corvallis, Oregon

Willamette River Model WIRQAS Water Resources Division, U.S. Geological Survey, Washington, D. C.

Estuary Hydrodynamic/ HYD/SAL Texas Water Developnwnt Board, Salinity Model Austin, Texas

ECOLOGIC MODELS (All Numerically Integrated)

River Quality Model QUAL-11 Water Resources Engineers, (QUAL-I modification) Walnut Creek, California

Lake Ecologic Model LAKECO Water Resources Engineers, (DRM modification) Walnut Creek, California

Estuary Ecologic 140del ECOMOI) U.S. Environmental Protection Agency, Washington D. C.

Estuarine Aquatic Ecologic ESTECO Texas Water Development Board/ Model Water Resources Engineers, Austin, Texas

Lake Phytoplankton Model LAKE-1 Department of Civil Engineering Manhattan College, New York, New York

Eutrophic Lake Quality Model --- Battelle Pacific Northwest Labs, Richland, Washington

Lake Ecologic Model CLEAN

Water Quality in River- WQRRS U.S. Army Corps of Engineers, Reservoir Systems Hydrologic Engineering Center, Davis, California

Narragansett Bay Hydrodynamic --- Department of Ocean Model Engineering, University of Rhode Island, Narragansett, Rhode Island Appendix E Tables of Responses to OTA Survey of Actual and Potential State-Level Model Use

OTA surveyed State agency employees in June, 1980 to determine their current use of models and their perceptions of potential model use; data from Part I of this survey are tabulated in the following pages. The respondents were asked to indicate their use of models in 33 water resource issue areas (left-hand column) for three categories of use (across the top of the tables): A) operations and management, B) planning and policy, and C) other. In these tables, the letter ‘X’ represents some model use, and ‘O’ indicates extensive model use. The fourth category at the top of the tables, labelled ‘N, reports instances in which State agency personnel specifically indicated that models are not used, or that no potential for model use exists.

216 App. E—Tables of Responses to OTA Survey of Actual and Potential State-Level Model Use 217

ALABAMA ALASkA ARIZONA

Exist ing Potential Existing Potential Existing Potential ABCN ABCN ABCN ABCN ABCN ABCN

1. Flood Forecast. xxx x x x 2. Drought/L.Flow xxx xx x xx 3. Streamflow Reg. X X xx x x xx 4. Instream Flow xx xx xx x x 5. Dem. Water S. x xxx xx x x 6, 1rr. Agri. x xxx x 7. Offatream Use x xxx xx x x 8. W. Use Effic. x xxx x x x 9. Urban Runoff x xxx xx x x 10. Erosion/Seal. x xxx xx x x 11. Salinity x xxx x x 12. Agrlc. Runoff x xxx xx x x 13. Airborne Poll. x x xx x x 14. Waste L. Alloc. Oox Oox xx x x 15. Thermal Poll. x xx x x 16. Toxic Materials x xx xx x x 17. Drink.Water Qual. x x xx x x 18. W.Q. Impacts x xx xx x x 19. G.W. Supplie8 x xx xx x xx 20. Conjunct. Use x x xx o xx 21. Accid. Contain. x xxx xx x x 22, Ag . Poll.-gow. x xxx xx x xx 23. W. Disposal-g.w. x xxx xx x xx 24. Salt W. Intrus. x xxx xx x x 25. Water Pricing x x“ x x 26. Costs/Poll.Con. x x x x 27. Benefit/Cost x x x x 28. Dev. Impllcst. x x x x 29. Forecast. Use x xxx x x 30. Social Imp. x x x x 31. Risk/Benefit x x x x 32. Comp. W. Use x xxx x x 33. Unified R.B.M. xx xxx x x

84-589 D - 82 - Is 218 ● Use of Models for Water Resources Management, Planning, and policy

ARKANSAS CALIFORNIA CDLORADO Exist ing Potential — Existing Potential Existing Potential ABCN ABCN ABCN ABCN ABCl!l ABCN

10 Flood Forecast. xx Oxx x x 2. Drought/L.Flow xxx xxx x x 3. Streamflow Reg, 00 00 x x 4. Instream Flow ox 00 x x 5. Dem. Water S. 00 xx xx

60 Irr. Agrlo 00 xx x x 7. Offstream Use x xx x x 8e W. Use Efflc. 00 xx xx 9. Urban Runoff x xx x x 10. Erosion/Seal. xx xx xx x x

110 Salinity x Xox x x 12. Agric. Runoff x x xx x x 13. Airborne Poll. x x x x 14. Waste L. Alloc. XX xx x xxx x x 15. Thermal Poll. xx x x 16. Toxic Materials x x xx x x 17. Drink.Water Qual. xx x xxx x x 18. W.Q. Impacts xx x xxx x x 19. G.W. Supplies xxx xxx o 0 20. Conjunct. Use xxx xxx o 0 21. Accid. Contain. x xx x x

22, Ag ● Poll.-g.w. x xxx x x 23. W. Disposal-g.w. xx xx x x 24. Salt W. Intrus. xx xxx x x 25, Water Pricing x xx x x 26. Costs/Poll.Con. x x x x 27. Benefit/Cost x xx x x 28. Dev. Implicat. x x x x 29. Forecast. Use xx x x x 30. Social Imp, x x x x 31. Risk/Benefit xxx x x 32. Comp. W. Use xx xx x x 33. Unified R.B.M. xx 00 x x App. E—Tables of Responses to OTA Survey of Actual and Potential State-Level Model Use 219

CONNECTICUT DELAWARE FLORIDA

Existing Potential Exist ing Potential Existing Potential ABCN ABCN ABCN ABCN ABCN ABCN

10 Flood Forecast. XX xx x xxx 2. Drought/L.Flow x Xo x Oxx xxx 3. Streamflow Reg. X xx x 00 xx 4. 1nstream Flow x xx x x xx 5* Dem. Water S. x xx x x xx xx 6. Irr. Agri. x x x x x 7. Offstream Use x xx x x x 8e W. Use Effic. x xx x x 9. Urban Runoff x xxx x xx xx 10. Erosion/Seal. x xxx x xx 11. Salinity o x x x xxx 12. Agric. Runoff x xxx x xx 13. Airborne Poll. xx xxx x x x 14. Waste L. Alloc. Oox ox x x 15. Thermal Poll. Xxo x xx 16. Toxic Materials x Xox x xx xx 17. Drink.Water Qual. X xxx x x 18. W.Q. Impacts xx Xox x xx 19. G.W. Supplies x Oox x x xx xx 20. Conjunct. Use x Oox x xx xx 21. Accid. Contain. xx xxx x xx x 22. Ag. Poll.-g.w. x x x xx x 23. W. Disposal-g.w. X xxx x xx x xx 24. Salt W. Intros. x x x xx xx xx 25. Water Pricing x xxx x xx 26. Costs/Poll. co. x xx x 27. Benefit/Cost x xxx x xx 28. Dev. Impli=t. x xx x x xx 29. Forecast. Use x xx x xx 30. Social Imp. x xx x xx 31. Risk/Benefit x xx x xx 32. Comp. W. Use x xxx x xx 33. Unlfled R.B.M. x xxx x xx 220 ● Use of Models for Water Resources Management, Planning, and Policy

GEORGIA HAWAI1 IDAHO

Exi.sting Potential Existing Potential Existing Potential ABCN ABCN ABCN ABCN ABCN ABCN

1. Flood Forecast. x x xx x x 2. Drought/L.Flow x x xxx x x 3. Streamflow Reg. x x x xx x x 4. Instream Flow x x xx x x 5. Dem. Water S. x x x xx x xx 60 Irr. Agrl. x x x x x 7. Offstream Use x x x xx 8. W. Use Effic. x x xx x xx 9. Urban Runoff x x xx x xx 10. Erosion/Seal. x x xx x xx

110 Salinitv x x xx x xx 12. Agric. Runoff x x xxx x xx 13. Airborne Poll. x xx 00 00 14. WasteL. Alloc. 00 00 xxx ox xx 15. Thermal Poll. x x x x xx 16. Toxic Materials x x xx xx xx 17. Drink.Water Qual. x xxx x xx 18. WeQ . Impacts x x xx xx xx 19. G.w. Supplies o xxx xxx x x 20. Conjunct. Use x x xxx x x 21. Accid. Contain. x x xxx x xx 22. Age Poll.-g.w. x x xxx x xx 23. W. Msposal-g.w. x x xxx x xx 24. Salt W. Intrus. x x xxx x x 25. Water Pricimz x x xx x x 26. Costs/Poll.Con. x x xxx x xx 27. Benefit/Cost x x x xx x xx 28. Dev. Im~licat. x x x x x 29. Forecast. Use x xx xx x xx 30. Social Imp. x x x x xx 31. Risk/Benefit x x xxx x xx 32. Comp. W. Use x x xxx x xx 33. Unified R.B.M. 00 00 x xx x xx App. E—Tables of Responses to OTA Survey of Actual and Potential State-Level Model Use ● 221

ILLINOIS INDIANA IOWA

Existing Potential Existing Potential Existing Potential ABCN ABCN ABCN ABCN ABCN ABCN

1. Flood Forecast. X X xx Oox Oox Xo x 2. Drought /L. Flow xxx xxx x xx x xx 3. Streamflow Reg. XX xx x x x xx 4. Inatream Flow x xx x x x xx 5. Dem. Water S. xxx xx x x x xx 6. Irr. Agri. xx x x xxx 7. Offstream Use xx x x x xx 8. W. Use Effic. xx xx x x x xxx 9. Urban Runoff x x x x x x 10. Erosion/Seal. x x x x x xxx 11. Salinity x x x x x x 12. Agric. Runoff x x x x x 13. Airborne Poll. x x x x x 14. WasteL. Alloc. X xx 00 ox x 15. Thermal Poll. xx x x x 16. Toxic Materials x x xx x 17. Drink.Water Qual. x x xx x 18. W.Q. Impacts xx xx x 19. G.W. Supplies xx xx x x xx 20. Conjunct. Use x xx x xx x xx 21. Accid. Contain. xx xx x xx 22, Ag . Poll.-g.w. x x x x x xx 23. W. Disposal-g.w. x x x x xx 24. Salt W. Intrus. X x x x 25. Water Pricing x xx x xx 26. Costs/Poll.Con. x x x 27. Benefit/Cost xx xx x 28. Dev. Implicat. x x x xx 29. Forecast. Use xx xx x xx 30. Social Imp. x x x 31. Risk/Benefit x xx x 32. Comp. W. Use x xx x xx 33. Unified R.B.M. x xx x xx 222 ● Use of-Models for Water Resources Management, Planning, and Policy

KANSAS KENTUCKY LOUISIANA

Existing Potent Ial Existing Potent ial Existing Potential ABCN ABCN ABCN ABCN ABCN ABCN

1. Flood Forecast. x x xx xx ox xx 2. Drought/L.Flow xxx xx Xo xxx x xx 3. Streamflow Reg. X X xx x xx o 0 4. Instream Flow x xxx x xx x xx 5. Dem. Water S. xxx x x xxx x xxx 6- Irr. Agri. xxx x x x x xx 7. Offstream Use xxx x x xxx x xx 8. W. Use Effic. xxx x x xx xxx 9. Urban Runoff x xx x xx x xxx 10. Erosion/Seal. x xx xxx 000 x xx 11. Salinity x x xxx xxx x xx 12. Agric. Runoff x x x xxx x xxx 13. Airborne Poll. x x xx xx x xxx 14. WasteL. Alloc. X xx xx xxx ox xx

150 Thermal Poll. x xx x xx x xx 16. Toxic Materials x x x 000 x xxx 17. Drink.Water Qual. x x x 000 x xxx 18. W.Q . Impacts x x xx 000 x xxx 19. G.W. Supplies xxx xx xxx 000 xx 00 20. Conjunct. Use xxx x x xxx xx 00 21. Accid. Contain. x x x xxx x xx 22. Ago Poll.-g.w. x x x xx x xx 23. W. Disposal-g.w. x x x xxx x xx 24. Salt W. Intrus. x x x x x xx 25. Water Pricing x xxx x x x xx 26. Costs/Poll.Con. x x x xxx x xx 27. Benefit/Cost x xxx x x x x 28. Dev. Implicat. xx x x x x 29. Forecast. Use xx xx x x x xx 30. Social Imp. x x x x x 31. Risk/Benefit x x x x x x 32. Comp. W. Use xx xx x xx x x 33. Unified R.B.M. xx xx x xx x xx App. E—Tables of Responses to OTA Survey of Actual and Potential State-Level Model Use ● 223

MAINE MARYLAND MASSACHUSETTS

Exist ing Potential Existing Potential Existing Potential ABCN ABCN ABCN ABCN ABCN ABCN

10 Flood Forecast. XX xx xx xx x x 2. Drought/L.Flow xx xx x x 3. Streamflow Reg. XX x x x 4. Instream Flow x xx x x x 5. Dem. Water S. x xx x x 6. 1rr. Agrl. x xx x x I 7. Offstream Use xx x x 8. W. Use Effic. x xxx x xx 9. Urban Runoff x xx x x x xxx iO. Erosion/Seal. x xx x x x xxx 11. Salinity x x xx xx x xxx 12. Agric. Runoff x xxx x x x xxx 13. Airborne Poll. x xxx xx x x x 14. Waste L. Alloc. x xx xx xx xx xx 15. Thermal Poll. xxx x x x xx 16. Toxic Materials xxx x x x xx 17. Drink.Water Qual. X X xx x x x xx 18. W.Q. Impacts x xx x xx x xx 19. G.W. Supplies x xx x xx xx xx 20. Conjunct. Use x xx x x x xx 21. Accid. Contain. x xx x xx x xx 22. Ag. Poll.-g.w. x xx x xx x xx 23. W. Disposal-g.w. x xxx x x x xx 24. Salt W. Intrus. x xx x x x x 25. Water Pricing x xx x x x x 26. Costs/Poll.Con. x x x x x x 27. Benefit/Cost x xx x x x x 28. Dev. Implicat. x x x x x x 29. Forecast. Use x xx x x x x 30. Social Imp. x x x x x x 31. Msk/Benefit x xx x x x x 32. ComD. W. Use x xx x x x x 224 Use of Models for Water Resources Management, Planning, and Policy

MICHIGAN MINNESOTA MISSISSIPPI

Existing Potential Existing Potential Existing Potential ABCN ABCN ABCN ABCN ABCN ABCN

1. Flood Forecast. x xx x x x xx 2. Drought/L.Flow x x x xx x xx 3. Streamflow Reg. x x x x xx xx 4. Instream Flow x xx xx xx x x 5* Dem. Water S. x x x xx x x 6. Irr. Agri. x xx x xx x x 7. Offstream Use x x x xx x x 8. W. Use Effic. x x x xx x x 9. Urban Rmoff x xx xx xxx x xx 10. Erosion/Sed. x xx xx xxx x xx 11. Salinity x x xx x xx 12. Agric. Rtmoff x xx xx xxx x x 13. Airborne poll. x xx x xxx x xx 14. Waste L. Alloc. x xx ox xxx Xo xx 15. Thermal Poll. x xx x xxx xx xx 16. Toxic Materials x xx xx xxx x xx 17. Drink.Water Qual. x xx xxx x xx 18. W.Q. Impacts x xx xx xxx x xx 19. G.W. Supplies x xx x xxx x xx 20. Conjunct. Use x xx x xxx x xx 21. Accid. Contain. x xxx x xxx x xx

22. Ago Poll.-g.w. x xx x xxx x xx 23. W. Disposal-g.w. x xx x xxx x xx 24. Salt W. Intrus. x x x x xx 25. Water Pricing x x x xx x x 26. Costs/Poll.Con. x x x xx x x 27. Benefit/Cost x x x xx x x 28. Dev. Impliat. x x x xx x x 29. Forecast. Use x x xx x x 30. Social Imp. x x xx x x 31. Risk/Benefit x x xx x x 32. Comp. W. Use x xx x xx x x 33. Unified R.B.M. x xx x xx x x App. E—Tables of Responses to OTA Survey of Actual and Potential State-Level Model Use 225

MISSOURI MONTANA NEBKASKA

Existing Potential Existing Potential Existing Potential ABCN ABCN ABCN ABCN ABCN ABCN

1. Flood Forecast. x xxx ox ox x x 2. Drought/L. Flow x xxx o 3. Streamflow Reg. x xxx o x x 4. Instream Flow x )$ x x xx x x 5. Dem. Water S. x xxx x x 6. Irr. Agri. x xx x xx xx 7. Off stream Use x xx x x 8. W. Use Effic. x xxx x xx 9. Urban Runoff xx x x 10. Erosion/Seal. xx x x x 11. Salinity xx x x 12. Agric. Runoff xx x xx xx 13. Airborme Poll. xxx xxx x xx xx 14. Waste L. Alloc. xx x x 15. Thermal Poll. xx x x 16. Toxic Materials xx x x 17. Drink. Water @al. x xx x x x 18. W .Q. Impacts xx x xx xx 19. G.W. Supplies x xxx x x 00 Xo 20. Conjunct. Use x xxx x x ox xx 21. Accld. Contain. x xxx x x 22. Ag . Poll. -g. w. xxx x x xxx xx 23. W. Disposal-g .w. xx x x 24. Salt W. Intrus. xx x x x 25. Water Pricing xxx x x x 26. Costs /Poll .Con. x xx x x 27. Benefit/Cost xx x x 28. Dev. Impli=t. xx x x x 29. Forecast. Use xx xx 30. Social imp. x xxx x x x 31. Risk/Benefit x x 32. CoIQp. W. Use xx x 33. Unified R.B.M. xxx x 226 Use of Models for Water Resources Management, Planning, and policy

NEVADA NEW HAMPSHIRE NEW JERSEY

Existing Potential Existing Potential Existing Potential ABCN ABCN ABCN ABCN ABCN ABCN

10 Flood Fore-st. XO x x 2. Drought/L.Flow xx Xo 3. Streamflow Reg. X X o 4. Instream Flow Xo o 5. Dem. Water S. xx x x x 6. Irr. Agri. xx x 7. Offstream Use xx x 8. W. Use Effic. xx x x x 9. Urban R-off x x x x x 10. Erosion/Seal. x xx x x x 11. Salinity x x x x xxx xxx 12. Agric. Runoff xx x x x xx 13. Airborne Poll. xx x x x x 14. Waste L. Alloc. O 0 x x xxx xxx

150 Thermal Poll. Xo x x xx 16. Toxic Materials XX x x x xxx 17. Drink.Water Qual. X xx x x x x 18. W. Q. Impacts 00 xx x xx 19. G.W. Supplies xx xx x xx 20. Conjunct. Use xx xx x xx 21. Accid. Contain. x xx x xx

22. Ago Poll.-g.w. x x x xx 23. W. Disposal-g.w. x xx x xx 24. Salt W. Intrus. x x xx 25. Water Pricing xx xx x xxx 26. Costs/Poll.Con. x x 27. Benefit/Cost Xo x 28. Dev. Impli@t. X xx 29. Forecast. Use x xx 30. Social Imp. xx 31. Risk/Benefit xx 32. Comp. W. Use x xx x x 33. Unified R.B.M. x xx x x App. E— Tables of Responses to OTA Survey of Actual and Potential State-Level Model Use . 227 —.————.-——.——— —.—

NEW MEXICO NEW YORK NORTH CAROLINA

Existing Potential Existing Potential Existing Potential ABCN ABCN ABCN ABCN ABCN ABCN

10 Flood Forecast. X xx x x x xxx 2. Drought /L. Flow x xx Xo xx xx 3* Streamflow Reg. X xx o xx xxx 4. Instream Flow x x o xx xxx 5. Dem. Water S. xx xx x x xx 6. 1rr. Agri. xx xx x x xxx 7. Off stream Use xx xx x x xx 8. W. Use Effic. xx xx x x xxx 9. Urban Runoff x x xx x xxx 10. Erosion/Seal. x x xx x xx 11. Sallnity x x x xx 12. Agric. Runoff x x xx x xx 13. Airborne Poll. xx xx xx x xx 14. Waste L. Alloc. X X xx xx ox xx 15. Thermal Poll. x xx xxx xx 16. Toxic Materials XX xx x x xx 17. Drink. Water Oual. x x xx xxx 18. W.Q. Impacts xx xx xx xxx xxx 19. G.W. Supplies ox xx o x xxx 20. Conjunct. Use ox xx x x xxx 21. Accid. Contain. x xx x xxx 22. Ags poll. -~.ti. x x x xxx 23. W. Disposal-g. w. x x x xx 24. Salt W. Intrus. XX xx x xxx 25. Water Pricing x x x x x xx 26. Costs /Poll .Con. x x x xx x xx 27. Benefit/Cost xx x o xxx x xx 28. Dev. Implicat. x x x xxx x xx 29. Forecast. Use x x x x x xxx 30. Social Imp. x x x xxx x x 31. Risk/Benefit x x x xxx x x 32. Comp. W. Use x x x xx x xx 33. Unified R.B.M. x x o xx x xx 228 . Use of Models for Water Resources Management, Planning, and Policy

NORTH DAKOTA OHIO OKLAHOMA

Existing Potential Existing Potential Existing Potential ABCN ABCN ABCN ABCN ABCN ABCN

1. Flood Forecast. x x 00 00 x xx 2. Drought /L. Flow x xx 00 00 x xx 3. Streamflow Reg. X ox 00 00 x xx 4. Inatream Flow x xx x xx x xx 5. Dem. Water S. x xx x xx x xx 6. Irr. Agri. x x x xx x xx 7. Off stream Use x xx x x x xxx 8. W. Use Effic. x xx x xx x xx 9* Urban Runoff xx 00 x xx 10. Erosion/Seal. x xx x xx

110 Salinity x x x xx 12. Agric. Runoff x xx x xx 13. Airborne Poll. 00 00 x xx 14. Waste L. Alloc. 00 00 x xx 15. Thermal Poll. 00 00 x xx 16. Toxic Materials x 00 x xx 17. Drink.Water @al. x xx x xx 18. W.Q. Impacts 00 00 x xx 19. G.W. Supplies ox xx 00 00 xx xxx 20. Conjunct. Use x xx xx xx x xx 21. Accid. Contain. x xx x x x xx 22. Ag. Poll.-g.w. x xx x x 23. W. Disposal-g.w. x xx xx xx x x 24. Salt W. Intros. x x x x x x 25. Water Pricing x x xx x x 26. Costs/Poll.Con. x x xx x x 27. Benefit/Cost x x xx x x 28. Dev. Impllmt. x x xx x xx 29. Forecast. Use o x x x x 30. Social Imp. Xo xx x x x x 31. Risk/Benefit x xx x x 32. Comp. W. Use x x x x 33. Unified R.B.M. x x xx App. E—Tables of Responses to OTA Survey of Actual and Potential State-Level Model Use . 229

OREGON PENNSYLVANIA RHODE ISLAND

Existing Potential Existing Potential Existing Potential ABCN ABCN ABCN ABCN ABCN ABCN

1. Flood Forecast. x xx x xx xx xx 2* Drought /L .Flow x xx x xx x Xo 30 Streamflow Reg. x xx ox x xx 4. Instream Flow x xx x x x xx 5. Dem. Water S. x xx xx x xx 6. 1rr. Agrl. x xx xx x x 7. Off stream Use x xx x x xx 8. W. Use Effic. x xx x xx 9. Urban Runoff x xx x xx 10. Erosion/Seal. x xx x x 11. Salinity x xx x x 12. Agric. Runoff x xx x x 13. Airborne Poll. xx xx x x 14. Waste L. Alloc. ox xx xx xx 15. Thermal Poll. ox xx x xx 16. Toxic Materials 00 xx xx 17. Drink.Water Qual. 00 xx x x 18. W.Q. Impacts 00 xx x xx 19. G.W. Supplles x x xx xx 00 20. Conjunct. Use x x x xx 00 21. Accid. Contain. xx xx xx 22. Age Poll.-g.we xx x xx 23. W. Disposal-g.w. xx x xx xx 24. Salt W. Intrus. x x x xx 25. Water Pricing x x 26. Costs/Poll.Con. x x xx xx 27. Benefit/Cost x o xxx xx 28. Dev. Implimt. x x xxx 29. Forecast. Use x x x xx 30. Social Imp. x x xxx 31. Risk/Benefit x x xxx xx 32. Comp. W. Use x x xx xx 33. Unified R.B.M. x o xx 00 230 Use of Models for Water Resources Management, Planning, and Policy

SOUTH CAROLINA SOUTH DAKOTA TENNESSEE

Existing Potential Existing Potential Existing Potential ABCN ABCN ABCN ABCN ABCN ABCN

1. Flood Forecast. x x x x 2. Drought/L.Flow x x 3. Streamflow Reg. x xx x x 4. Instream Flow x x 5. Dem. Water S. x x 60 Irr. Agri. x x 7. Offstream Use x x 8. W. Use Effic. x x 90 Urban Runoff x xx x x 10. Erosion/Seal. x xx xx xxx x x 11. Salinity x xxx x x 12. Agric. Runoff x xx x x 13. Airborne Poll. xxx 14. Waste L. Alloc. O 0 x xxx o 0 15. Thermal Poll. x x x o 16. Toxic Materials X x x x 17. Drink.Water Qual. X xxx x x 18. W.Q . Impacts xx xx x xx 19. G.W. Supplies x xx ox x x 20. Conjunct. Use x xx xx x x 21. Accid. Contain. x xx x x x 22. Ago Poll.-g.w. x xx x x x 23. W. Disposal-g.w. x xx x x x 24. Salt W. Intrus. x xx x x x 25. Water Pricing x xx x xx x x 26. Costs/Poll.Con. x x 27. Benefit/Cost x x x 28. Dev. Implicat. x x 29. Forecast. Use x x 30. Social Imp. x x 31. Risk/Benefit x x 32. Comp. W. Use x xx x x 33. Unified R.B.M. x xx App. E—Tables of Responses to OTA Survey of Actual and Potential State-Level Model Use ● 231

TEXAS UTAH VERMONT

Existing Potential Existing Potential Existing Potential ABCN ABCN ABC Ii ABCN ABCN ABCN

1. Flood Forecast. 00 x xx xxx x xx 2. Drought/L.Flow x xx xxx x xx 3. Streamflow Reg. xx xxx xxx x xx 4. Instream Flow 00 x xx xxx x xx 5. Dem. Water S. x xx xxx xxx x 6. Irr. Agri. Xox xxx xxx xxx x 7. Offstream Use ox xxx xxx xxx x 8. W. Use Effic. Oox xxx xx xxx x 9. Urban Runoff o xxx x xxx x xx 10. Erosion/Seal. x xx x xxx x 11. Salinity x xx xx xxx x 12. Agric. Runoff o x xx xxx x 13. Airborne Poll. xxx xx xx xxx 00 00 14. Waste L. Alloc. x xx xxx ox 00 15. Thermal Poll. Xox xxx xx xxx x xx 16. Toxic Materials Oox xx x xxx x xx 17. Drink.Water Qual. O xxx x xxx x xx 18. W.Q . Impacts x xx xx xxx xx 19. G.W. Supplies Xox xxx xxx xxx x x 20. Conjunct. Use Xo x xxx xxx x 21. Accid. Contain. x xx x xxx x xx 22. Ag. Poll.-g.w. x xxx x xxx x 23. W. Disposal-g.w. x xxx x xxx x 24. Salt W. Intrus. x xxx x xxx x 25. Water Pricing x x xx xxx x 26. Costs/Poll.Con. xx xxx x 27. Benefit/Cost o x xx xx x 28. Dev. Implicat. o x xx xx x 29. Forecast. Use o x xx xxx x 30. Social Imp. xx xxx x 31. Risk/Benefit x x xx xxx x 32. Comp. W. Use x x xx xx x 33. Unified R.B.M. xx xxx x x .

232 . Use of Models for Water Resources Management, Planning, and Policy

VIRGINIA WASHINGTON WEST VIRGINIA

Existing Potential Existing Potential Existing Potential ABCN ABCN ABCN ABCN ABCN ABCN

1. Flood Forecast. x x xx Xo Xo 2* Drought/L.Flow xx x xx Xo Xo 30 Streamflow Reg. xxx x xx Xo Xo 4. Instream Flow x Xo xx x 5. Dem. Water S. x xx xx 6. Irr. Agri. x xx xx 7. Offstream Use x xx 8. W. Use Effic. x x x x 9* Urban Rutoff x xx xx 10. Erosion/Seal. x xx xx 11. Salinity x 12. Agric. Rmoff x 13. Airborne Poll. x 14. Waste L. Alloc. Xox Xo Xo 15. Thermal Poll. x Xo Xo 16. Toxic Materials x xx xx 17. Drink.Water Qual. x 18. W.Q. Impacts xxx Xo Xo 19. G.W. Supplies Oxx xx x 20. Conjunct. Use x x Xo x o 21. Accid. Contain. x x 22. Ag. Poll.-g.we x x x 23. W. Disposal-g.w. x x o 24. Salt W. Intrus. x x x 25. Water Pricing x x x 26. Costs/Poll.Con. x 27. Benefit/Coat x x 28. Dev., Impliat. x x 29. Foreumt. Use x x x x 30. Social Imp. x x 31. Risk/Benefit x x 32. Comp. W. Use x x 33. Unified R.B.M. x x x x App. E—Tables of Responses to OTA Survey of Actual and Potential State-Level Model Use . 233

WISCONSIN WYOMING WASHINGTON, D.C.

Existing Potential Existing Potential Existing Potential ABCN ABCN ABCN ABCN ABCN ABCN

1. Flood Forecast. X X xx x xxx x x 2. Drought/L.Flow xx ox x xxx xxx x 3. Streamflow Reg. xxx xx x xxx x x 4. Instream Flow x ox xxx x x 5. Dem. Water S. x x x xxx x x 6. Irr. Agri. x ox x xx x x 7. Offstream Use x ox x xx x x 8. W. Use Effic. x x x xxx x x 9. Urban Runoff xx xxx xxx xxx Xo 10. Erosion/Seal. xxx x xxx xxx x x 11. Salinity x x xx xx x 12. Agric. Runoff x x xx xx o x 13. Airborne Poll. xx xx x x x x 14. Waste L. Alloc. 00 x x x xx x 15. Thermal Poll. xx x x x x x 16. Toxic Materials x x x x x x 17. Drink.Water Qual. x x x x x x 18. W.Q . Impacts x xx xxx xxx x x 19. G.W. Supplies x xx xx x x 20. Conjunct. Use x xx xxx xxx x x 21. Accid. Contain. x x xxx xxx x x 22. Ag . Poll.-g.w. x xx xxx xxx x x 23. W. Disposal-g.w. x xx xxx xxx x x 24. Salt W. Intrus. x x x x x x 25. Water Pricing x x x x x x 26. Costs/Poll.Con. xx xx x x xx x 27. Benefit/Cost x x x x x x 28. Dev. Implicat. x ox x x x x 29. Forecast. Use x xx x x x x 30. Social Imp. x x x x x x 31. Risk/Benefit x xx x x x x 32. Comp. W. Use x x x x x x 33. Unified R.B.M. o x x x x x Index Index

Ada, Okla., 168 Cooperative Instream Flow Service Group (see agriculture Instream Flow Group as greatest user of water, 31 Cornell university, 6 irrigation in, 109, 128-129 Corps of Engineers (see Army Corps of Engineers) as a water pollution source, 33 Council on Environmental Quality (CEQ aquatic life models used by, 182 water quality impacts on, 140-141 Argonne National Laboratory, 177 Department of Agriculture (USDA), 111 Army Corps of Engineers, 9, 11, 110, 135, 136, assistance to States, 99 157, 158 drought and low-flow models provided by, 109 assistance to States, 99 Economic and Statistics Service (ESS), 172 Coastal Engineering Research Center Forest Service, 71, 72, 174 (CERC), 177 Land and Water Conservation Task Force, 92 drought and low-flow models provided by, 109 Land and Water Resources and Economic Engineering Computer Programs Library, 60 Modeling System (LAWREMS), 17, 88, Hydrologic Engineering Center (HEC), 10, 15, 92-93, 172 17, 20, 51, 53, 60, 84-85, 92, 108, 177 models used by, 172-176 models used by, 176-177 Science and Education Administration Office of the Chief of Engineers, 60 (SEA), 174-175 role in water resources, 176 Soil Conservation Service (SCS), 75, 78, 108, thermal pollution modeling services of, 112 135, 136, 157, 172, 175 training programs conducted by, 106, 108 Department of Commerce, 82, 158 Waterways Experiment Station (WES), 177 models used by, 176-177 Athens, Ga., 91 National Oceanic and Atmospheric Administration (NOAA), 175-176 Bay St. Louis, Miss., 86 Department of Energy (DOE) Bureau of Mines, 72 Federal Energy Regulatory Commission Canada (FERC), 178 survey of environmental management simulation Office of Environmental Assessments, 177-178 models in, 201 Department of the Interior (DOI), 72, 77, 78 carbon tetrachloride, 140 79, 82, 87 Catalog of Information on Water Data, 81 Bureau of Land Management (BLM), 178 Center for Water Quality Modeling (see Bureau of Mines, 178-179 Environmental Protection Agency) Bureau of Reclamation, 157, 158, 180-181 Chase Econometrics, Inc. Fish and Wildlife Service, 179 macroeconomic model of, 157 models used by, 178-182 Chesapeake Bay, 183, 186 Office of Surface Mining, 179 Kepone in, 136 Office of Water Data Coordination storm surges in, 186 (OWDC), 80-82 coastal areas Office of Water Research and Technology index to stations in, 81 (OWRT), 19, 20, 21, 79, 168, 179 coastal zone management, 85 State Institute Program, 79-80 Colorado River Basin, 87 University Water Research Program, Colorado River Basin Salinity Control Program, 70 9, 10, 19, 20 Congress U.S. Geological Survey (USGS), 181-182 acts of (see legislation) Department of Transportation, 78 options available to, 11-12, 13-14, 16, 17-18, I.)01, (see Department of the Interior) 20-21 DRI Senate Select Committee on National Water macroeconomic model of, 157 Resources, 25 drought and low stream flow Connecticut River, 7 forecasting of, 109, 126

237 238 . Use of Models for Water Resources Management, Planning, and Policy economi c cand c and social issues, 29 Executive Order No. 11988, 8, 69, 174, 175 competitive water use, 116 floods cost/benefit analysis, 115, 157-158 assistance to States in control of, 99 costs of pollution control, 114-115, 157 control of, 4, 30, 108, 124-126 effects of pricing on water use, 114, 156-157 damage from, 30, 124 forecasting water use, 116, 159 distribution of information by Federal models for analysis of, 152-161 agencies, 108 regional economic development, 115-116, 158-159 forecasting of, 108, 124-126 risk/benefit analysis, 116, 159-160 insurance, 109 social impact, 116 warning systems for, 85 unified river basin management, 116, 161 Forest Service (see Department of Agriculture) Economic and Statistics Service (see Department of Agriculture) GAO (see General Accounting Office) Economic Assessment Model, 158 General Accounting Office (GAO), 60, 61, 73, 74, energy development, 85 75, 84 environmental impact evaluation, 85 survey on improving management of federally Environmental Protection Agency (EPA), 8, 9, 13, funded computerized models, 199 14, 33, 72, 78, 87, 136, 137, 138, 139, General Services Administration (GSA) 157, 168, 172 Federal Property Management Regulations, 83 Center for Water Quality Modeling, 17, 18, 50, Federal Software Exchange Center (FSEC), 17, 88, 91-92 18, 49, 83-84 Cleveland Electric Illuminating Co. v. EPA, 62 Great Lakes, 183 Environmental Research Laboratory, 91, 92 polychlorinated biphenyls (PCBS) in, 141 Holcomb Groundwater Model Clearinghouse, ground water, 29, 34, 37, 85 14, 18 availability of, 34, 146-147 Holcomb Research Institute, 50, 88, 168 conjunctive use of surface water and, International Clearinghouse for Groundwater 113-114, 146 Models (ICGWM), 17, 88-89 model types available for analysis of, 151-152 models used by, 182-185 model types used in resource analysis of, 144-146 Office of Research and Development (ORD), pollution of, 43, 114 90, 183 quality, 147-151 Office of Toxic Substances (OTS), 184 quantity and quality of, 143-152 Office of Water Enforcement, 184-185 saltwater intrusion in, 37-38, 40, 114 Office of Water Program Operations SCOPE International Assessment Project on (OWPO), 183 models of, 201 Office of Water Regulations and Standards as sole source of drinking water in Long Island, (OWRS), 183 N. Y., 40 Office of Water and Waste Management, 183 subsidence caused by withdrawal of, 147 Stormwater Management Model (SWMM), 15, supplies and safe yields of, 113 20, 50, 89-91, 105, 135 GSA (see General Services Administration) thermal pollution modeling services of, 112 Gulf Coast Hydroscience Center, 86 Executive Office of the President (EOP), 77 Executive Order No. 11988 (see flood plain management Holcomb Clearinghouse (see Environmental Protection Agency) Federal Council for Science and Technology Holcomb Research Institute (see Environmental Committee on Water Resources Research Protection Agency) (COWRR), 77 Hudson River Federal Emergency Management Agency, 71, 108 polychlorinated biphenyls (PCBS) in, 141 models used by, 186 hydroelectric power, 4, 109 Federal Insurance Administration (FIA), 186 hydrologic cycle, 121 Federal Software Exchange Center (FSEC) (see Hydrologic Engineering Center (HEC) (see Army General Services Administration Corps of Engineers) Fish and Wildlife Service, 87, 110 Flander’s Bay (Long Island, N.Y. ), 41, 42, 43 Illinois Pollution Control Board, 63 flood plain management, 85, 109, 176 Index to Stations in Coastal Areas, 81 Index . 239

Instream Flow Group, 12, 20, 51, 87-88, 110 Rural Clean Water Program, 175 Interagency Advisory Committee on Water Safe Drinking Water Act, 8, 14, 68, 72, 97, 140, Data, 81 179, 182, 183, 184 International Clearinghouse for Groundwater Soil and Water Resource Act, 69 Models (ICGWM) (see Environmental Soil and Water Resources Conservation Act, 8, Protection Agency) 172, 174, 175, 179, 182 Surface Mining Control and Reclamation Act, 8, James River, 183 69, 174, 179, 182 Kepone in, 136, 141 Toxic Substances Control Act, 8, 72, 140, 184 Johnson, Dr. William, 53 Watershed Protection and Flood Prevention Act, 174, 175 Kepone, 136, 141 Water Research and Development Act, 8, 11, 13, 77, 79, 82 Lakewood, Colo., 86 Water Resources Development Act, 174, 180, 182 Land and Water Resources and Economic Modeling Water Resources Planning Act, 8, 69, 97, 114, System (see Department of Agriculture) 115, 172, 175, 178, 182, 185 land-use planning, 85 Water Resources Research Act, 79 legislation Long Island, N,Y. Atomic Energy Act, 8, 70, 186 as-a case study of model use, 40-43 Brooks Act, 83 Long Island Regional Planning Board, 6 Clean Air Act, 137 Clean Water Act, 6, 8, 14, 70, 72, 97, 102, 110, mathematical models (see models) 111, 112, 114, 115, 135, 137, 138, 139, 140, Menlo Park, Calif., 86 172, 174, 175, 176, 179, 180, 182, 183, 185 Model Annotation Retrieval System (MARS), 89 Coastal Zone Management Act, 8, 69 models Colorado River Basin Salinity Act, 175 access to Federal, 106 Colorado River Salinity Control Act, 180 of agricultural runoff, 111, 136-137, 183 Endangered Species Act, 8, 69, 174, 180 of agricultural soil/water interaction, 122 Energy Conservation Standards for New of airborne pollution, 112, 137-138 Buildings Act, 64 alluvial process, 123 Federal Insecticide, Fungicide, and Rodenticide appropriateness of, 170-171 Act, 184 aquatic life impact, 112-113 Federal Power Act, 178 of aquifer characteristics, 102 Federal Reclamation Act, 8, 69, 180, 180, 182 Argonne Water Quality Accounting System Federal Water Pollution Control Act, 40, 68, (AQUAS), 177 138, 172 Automated Downstream Accounting Model Fish and Wildlife Coordination Act, 176, 179 (ADAM), 177 Flood Control Act, 8, 69, 174, 175, 176, baseflow, 121 178, 180 Bureau of Reclamation Economic Assessment Food and Agriculture Act, 174 Model (BREAM), 181 Forest and Rangeland Renewable Resources calibration of, 56-57 Act, 71 channel process, 123 Forest and Rangeland Renewable Resources characteristics affecting ease of using, 52-53 Planning Act, 174 Chemicals, Runoff, and Erosion from Intergovernmental Personnel Act, 87 Agricultural Management System National Environmental Policy Act, 8, 69, 139, (CREAMS), 175 153, 176, 180 clearinghouse for, 169 National Environmental Protection Act, 61, 186 Colorado River System Simulation (CRSS), 185 National Flood Insurance Act, 8, 69, 71, 186 of competitive water use, 116 National Forest Management Act, 71, 174 for conjunctive use of ground and surface water, Organic Act, 176 113-114 Resource Conservation Act (see Soil and Water constraints to use by States, 104-107 Resources Conservation Act) of contaminant transport, 144-146 Resource Conservation and Recovery Act, 8, 68, coordination of information on, 170 97, 140, 182 coordination mechanisms for, 80-84 240 . Use of Models for Water Resources Management, Planning, and Policy

in cost/benefit analysis, 115 oversight in development of, 59-61 data availability for, 73, 105, 167-168 personnel shortage for, 105-106 in data management, 29 in planning and policy development, 29, 41 decisionmaker understanding of, 73-74, 170 in pollution control, 39, 112, 114-115 definition of, 26-30 potential at the State level, 10 descriptive, 28, 29-30 predictive, 28 deterministic, 30 prescriptive, 30 dissemination of, 75 in the private sector, 167 documentation of, 107, 168 probabilistic (stochastic), 30, 166 for drinking water quality, 112 process, 121 in drought and low-flow forecasting, 109, 126 of receiving-water quality, 183 economic and social, 152-161, 166 references to studies of, 187-192, 202-206 of erosion and sedimentation, 135-136 in regional economic development, 39, 115-116 in erosion and sedimentation studies, Regional Energy Location Model (RELM), 180 33, 110, 136 in regulation, 29 evaluation of, 55-59 reliability and credibility of, 106-107 Exposure Analysis Modeling System research and development needs on, 165-167 (EXAMS), 183 Return Flow Quality Simulation Model, 181 Federal agency publications on, 187-192 in risk/benefit analysis, 39-40, 116 Federal agencies using, 172-186 of river basins, 27-28, 39, 116 Federal approaches to management of, 76-93 for salinity control, 136 Federal expenditures on water-related, 4, 9 in social impact assessment, 116 Federal programs using (table), 68-70 standardization of, 107 Federal use and support of water resource statistical, 121, 123-124 models, 67-93 State funding of, 107 in flood control, 30, 124-126 State government use of, 97-116 in flood and drought frequency analysis, 124 Strategic Environmental Assessment System general uses of, 5-8, 25-30 (SEAS), 178 in ground water assessment, 34-37, 38-39, 43, stream process, 123 146, 165-166 in streamflow regulation, 31, 59, 109, 126-127 of ground water flow, 144 support services for, 9, 47-53, 84-93 of ground water pollution, 39 of surface water flow and supply, 165 higher dimension, 167 in surface water flow and supply analysis, of instream flow, 110 121-124 of instream needs, 127-128 of surface water quality, 165 interaction between modelers and decisionmakers, of surface water salinity, 111 53-55 System of Watershed Automated Management interagency (Federal) coordination on, 75-76 Information (SWAMI), 175 in irrigation, 7, 122 of thermal pollution, 112, 139-140 issues related to, 10-21, 47-64 of toxic materials, 34, 140 lack of coordination among agencies using, 9 training in, 50-51 land drainage, 122 Universal Soil Loss Equation (USLE), 175 legal aspects of, 61-64, 171 of urban runoff, 110, 123, 134-135 legislation associated with use of, 8 used by Army Corps of Engineers, 176-177 in Long Island, N. Y., 41-43 used by Council on Environmental Quality, 182 Los Alamos Coal Use Modeling System used by Department of Energy, 177-178 (LACUMS), 177 user assistance in, 51-52, 88-93 maintenance of, 52, 75, 107, 169 user support of, 74-75 to meet State needs, 104-105 validation of, 56, 57-58, 168 Multiple-Objective Programing (MOP), 180 of wasteload allocation, 8, 33, 112, 138-139 National Weather Service River Forecast System Water Assessment System, 177 (NWSRFS), 176 for water budgeting, 41 of offstream water use, 109 in water conservation, 32 in operations and management, 29, 43 in water current studies, 41-42 Index ● 241

in water pricing, 40, 114 Pennsylvania, 172 of water quality, 140 pollution in water use forecasting, 40, 116 from agricultural runoff, 33, 41, 149-150 Water Use Information System (WUIS), 177 airborne, 33, 112 costs of controlling, 114-115 Nassau-Suffolk Regional Planning Board, 40, 41 of drinking water by bacteria and viruses, 34 National Academy of Sciences (NAS), 79 of drinking water by toxic chemicals, 33-34 Water Resources Research Review effects on aquatic life, 33 Committee, 78 from erosion, 33 National Bureau of Standards (NBS), 75 of ground water, 39, 43, 147-152 study of ways to improve utility of large-scale in Long Island, N. Y., 40 models, 200 point sources of, 38-141 National Commission on Water Quality, 138 from seawater intrusion, 150-151 National Dam Safety Program, 108 thermal additions to streams, 33, 72, 112 National Oceanic and Atmospheric Administration from urban and industrial areas, 147-149 (NC)AA), 108 from urban storm runoff, 33 National Pollution Discharge Elimination from waste disposal sites, 150 System, 63 polychlorinated biphenyls (PCBS), 141 National Research Council, 11 President Carter, 77 National Science Foundation (NSF), 21, 73, President of the United States, 77 74, 75, 168 survey of federally supported mathematical reservoirs, 121 models, 199 as multiple-purpose facilities, 6 water resources research funded by, 185 operations, 109 National Technical Information Service (NTIS), 17, sedimentation in, 136 49, 82, 82-83 Resources for the Future, 25 National Water Data Exchange (NAWDEX), 81-82 Reston, Va., 86 Nationwide Weather Service (NWS), 6, 7, 176 drought and low-flow models provided by, 109 San Joaquin Valley (California), 172 Nationwide Urban Runoff Program, 134-135 Secretary of Interior, 11, 77 Nebraska, 7 Smithsonian Scientific Information Exchange Nuclear Regulatory Commission (NRC), 72, 139 (SSIE), 82 models used by, 186 social issues (see economic and social issues) Soil Conservation Service (see Department of Occoquan Reservoir (Virginia), 6 Agriculture) Office of Management and Budget (OMB), 12, 80 Stormwater Management Model (SWMM) (see Office of Science and Technology Policy (OSTP), Environmental Protection Agency) 12, 77, 78, 79 streamflow regulation, 109 Office of Technology Assessment (OTA), 5, 9, 10, support services (see models) 11, 13, 16, 49, 50, 53, 67, 70, 73, 74, 75, 79, Supreme Court, 61 84, 108 surface water, 85 State modeling survey, 97-98 agricultural runoff, 111-112, 136-137 Technologies for Determining Cancer Risks From aquatic life, 112-113 the Environment, 140 availability of, 120-121 workshops on water resource modeling, 165-171 conjunctive use of ground water and, Office of Water Data Coordination (OWDC), 80-82 113-114, 146 Office of Water Research and Technology (OWRT) drinking water, 112 (see Department of the Interior) erosion and sedimentation, 110-111, 135-136 Ohio River, 140 eutrophication of, 133 carbon tetrachloride in, 140 evaporation of, 122

OSTP (see Office of Science and flow and supply of, 29, 108-110, 119-131, Technology Policy) 130, 165 model types used in quality analysis of, 132-134, Peconic River (Long Island, N.Y. ), 41 141-143 Pecos River Basin (New Mexico), 6 pollution of, 112, 132, 133, 137-138 — .

242 ● Use of Models for Water Resources Management, Planning, and Policy

quality of, 29, 110-113, 131-143, 165 domestic water supplies, 109-110, 128, 140 salinity of, 111, 136 drought and low stream flow, 30, 109 urban runoff, 110, 134-135 effect of urban storm runoff on, 33 use of, 121 Federal expenditures for, 4 watershed models, 121, 121, 121 Federal-State cooperation on, 12-13 instream flow needs, 31, 110 Tennessee Valley Authority (TVA), 6-7, 157 irrigation, 109 issues in, 26, 30-40, 99, 101, 101-102, 102-103, University Water Research Program (see 113-116 Department of the Interior) in Long Island, N. Y., 40-43 U.S. Geological Survey (USGS), 9, 10, 11, 15, 20, mathematical models of, 5-8, 26-30, 55-59 51, 82, 84, 108, 110, 111, 113, 135 offstream uses of, 31, 109, 129 Federal-State Cooperative Program, 86 pollution of, 32, 33, 72, 138-141 National Training Center, 86 quality of, 85 training programs conducted by, 106 research on, 11-12, 77, 78-80 Water Resources Division, 85-87 sedimentation in waterways, 33 State research institutes on, 79-80 wasteload allocation State use of models for, 101 definition, 138 streamflow regulation, 31-33, 59, 109 waste storage and utilization, 85 Water Resources Council, 12, 30, 81, 158, 172, 177 water (see specific entries, e.g. , surface water, models used by, 185 ground water, water resources) Principles and Standards of, 153 water resources Water Resources Scientific Information Center activities involved in managing, 30 (WRSIC), 16, 18, 49, 82 conservation of, 32-33, 110, 129 World Meteorological Organization, 59 demand for professionals in, 9

Us. GOVERNMENT PRINTING OFFICE : 1982 0 - 84-589