GEOLOGICAL SURVEY CIRCULAR 601-H

Role of Water in

Urban Planning and

Management

Role of Water in

Urban Planning and

Management

By William J. Schneider, David A. Rickert, and Andrew M. Spieker

WATER IN THE URBAN ENVIRONMENT

G E 0 L 0 G I CAL 5 U R V E Y C I R C U LA R 601- H

Washington J973 United States Department of the Interior ROGERS C. B. MORTON, Secretary

Geological Survey V. E. McKelvey, Director

First printing 1973 Second printing 1973

Free on application to the U.S. Geological Survey, Washington, D.C. 20242 FOREWORD

Urbanization-the concentration of people in urban areas and the consequent expansion of these areas-is a characteristic of our time. It has brought with it a host of new or aggravated problems that often make new demands on our natural resources and our physical environment. Problems involving water as a vital resource and a powerful environmental agent are among the most critical. These problems include the maintenance of both the quantity and quality of our water supply for consumption, for recreation, and general welfare and the alleviation of hazards caused by floods, drainage, erosion. and sedimentation.

A prerequisite to anticipating, recognizing, and coping intelligently with these problems is an adequate base of information. This series of reports is intended to show the relevance of water facts to water problems of urban areas and to examine the adequacy of the existing base of water information. 6 .;( .7ckut/'t;._,~l E. L. Hendricks, Chief Hydrologist

III

CONTENTS

Page

Forevvord ------III Albstract ------F.£1 Introduction ------1 Urban impact on vva+.er resources ------1 Purpose of circular ------2 Water in urban planning and management ------2 Relationship to overall natural resources ------2 Regional approach------3 Integration into urban planning and management ------3 Types of information ------4 Relation to planning ------4 F.lydrologic elements of urban vvater appraisals ------5 Relationship of hydrologic data to urban problems ------6 Aln evaluation matrix ------6 Washington-Baltimore case study ------7 Summary and discussion ------9

ILLUSTRATIONS

Page PLATE 1. Washington-Baltimore water-resources evaluation matrix ______In pocket

FIGURE 1. Simplified flow diagram of the urban planning process shovving interrelation of water-resources investigations and planning programs ------H5 2. Map showing the Washington-Baltimore urban area ------8

TABLE

Page TABLE 1. Sequence of hydrologic analysis applied to land use and planning functions ------H6 v

Water in the Urban Environment

Role of Water in Urban Planning and Management

By William J. Schneider, David A. Rickert, and Andrew M. Spieker

ABSTRACT divert water long distances at consideral'le cost. Concentrations of people in urban areas intensify New York City, for example, divert~· water water problems such as flooding and pollution, but these from more than 100 miles away to n1eet its deleterious effects on water resources can be minimized demands. or corrected by comprehensive planning and manage­ Water is used in urban areas to dispose of ment. Such planning of the water resources of an urban man's wastes. He disposes of sewage and indus­ area must be based on adequate hydrologic data. Through the use of a matrix, urban water problems trial wastes by discharging them into streams can be evaluated and availability of data assessed. The and other water bodies. The severity of the Washington-Baltimore metropolitan area is used as a resulting pollution depends upon the de:qoree of case study. The completed matrix provides both a means waste treatment and on the amount of waste for developing a meaningful dialogue between the effluent in relation to the amount of water hydrologist and the urban planner and a method for developing a work plan to insure consideration of available for dilution. Storm runoff also con­ water-resources data in urban planning. tributes heavy pollution loads as rainfall flushes contaminants from urban streets. The INTRODUCTION disposal of solid wastes in dumps and s~nitary landfills poses a pollution threat to ground­ Water is a vital resource for human activ­ water resources as water, leaching through the ities. Its natural distribution is governed by wastes, carries with it both biological and chem­ climate and the physical character of the land ical contamination. surface. Urbanization, however, has altered this Construction of housing and highways ex­ natural distribution as water has been utilized poses bare soil to accelerated erosion. In Fair­ to supply man's needs and to carry away his fax County, Virginia, highway construction in­ wastes. Water is, in a sense, both artery and volving 197 acres contributed 37,000 tons of vein to urban life. sediment to the local stream over a 3-year period. This sediment chokes streams s.nd fills URBAN IMPACT ON WATER RESOURCES reservoirs, severely limiting their uses for rec­ Urbanization has significantly altered both reation and esthetic enjoyment and their ca­ the quantity and quality of our water resources. pacity to accommodate floods. The concentration of people in urban areas has Flooding is increased by urban development. modified the natural landscape, bringing about Tht~ roofing and paving of land surfaces and water problems that strongly affect their daily insi;allation of storm sewers concentrate storm lives. runoff and increases the flooding hazard. For Large cities require huge amounts of water example, in a 1-square-mile area, complete to satisfy both domestic. and industrial needs. storm sewering and paving of 60 per~ent o:f To meet these needs, cities commonly have to the surface--comparable to dense residential

Hl housing-can increase the average annual flood more data and new ways of pr~senting and by a factor of more than four. Such increases interpreting these data. During recent years, in flooding have serious implications when one public awareness of water proble"lls has come considers that much of the urban growth in the about as part of the growing cor.cern for our United States is by encroachment upon flood deteriorating urban environment. The concern plains. for and the awareness of the environment as­ In addition to these physical effects on the pects of urban living have resulted in a chang­ water resources, urbanization also alters recz:e­ ing attitude toward urban planning. In some ational and esthetic values of water bodies. urban areas the traditional functk--Ial-economic Indiscriminate development of waterfront prop­ approaches to planning are being broadened in erty has reduced or even destroyed the esthetic scope by including consideration of the natural appeal and decreased the recreational potential ·resources of the area. of many areas. Litter and other wastes, as well Furthermore, our present urbar water prob­ as general degradation of the local environ­ lems have created a need for new types of data ment, have further depleted the value of the and new techniques of analysis as well as for water resource. increased demand fo~ the mort~ traditional Although water resources in urban areas are types of hydrologic data for both planning and altered by the urbanization process, the dele­ management. terious effects can be minimized or corrected In response to these needs, tl' ~ Geological by comprehensive planning and management. Survey established an Urban Water Program But such planning of the water resources of to develop as one of its objectivef the capabil­ urban areas must be based on adequate hydro­ ities of supplying hydrologic information in a logic data. form readily usable by urban c fficials. This circular deals with one major aspect of the PURPOSE OF CIRCULAR program-the adaptation of water-resources in­ Today a wealth of hydrologic data is a vail­ formation to urban planning and management. able to planners and managers. Much of it, It represents the efforts of the r.uthors, both however, is basic data that in its raw form has singly and jointly over a 3-year ra.riod, in de­ little, if any, direct application to most urban veloping a rationale and technique for relating water problems. These data have been collected hydrologic information to urban planning and either as part of general monitoring networks management. Others, of course, have con­ or as specialized data from specific projects. tributed significantly to this development, espe­ The principal agency in the collection of these cially William W. Barnwell, Anchorage, Alaska, data is the U.S. Geological Survey. and Kenneth E. Vanlier, University, Alabama. The basic data consists of observations of Although still preliminary and subject to fur­ both surface water and ground water. Surface­ ther revision, the approach has l'~n used as water data are mainly observations of stage the basis for preparing programs for several and flow; ground-water data are observations major urban areas. The rationale and tech­ of depth to the water table or the pressure head niques presented herein are intended to stimu­ in confined aquifers and of the permeability of late dialogue between hydrologists and planners aquifer materials. Data on the quality of these and to provide a framework for full considera­ waters, mostly on inorganic constituents, are tion of water resources in urban rlanning. also available. Many other types of special WATER IN URBAN PLANNING AND hydrologic data are available. These data are MANAGEMENT essential to the understanding of our water re­ sources, which is needed for intelligent plan­ RELATION TO OVERALL NATURAL RESOURCES ning and managing of urban areas. Public concern over environmental quality Although the available hydrologic data repre­ has focused sharp attention upon our national sent a significant contribution to management resources. The peaceful revolution from exploi­ of urban water resources, emerging new ap­ tation of land, water, and mineral"" to the con­ proaches to urban planning will require even servation and wise use of our natu~ai resources

H2 has brought with it both concern and under­ supply of good-quality water is a problen1 that standing of the interrelation of all natural re­ has reached near-crisis proportions in some sources. Indeed, it is more than an interrela­ urban areas. All these problems are reg·ional tion ; it is an interdependence. in scope and transcend local community boun­ Many examples of interdependence can be daries. The solutions to these problems must cited. Flood magnitudes are related to land likewise be undertaken on a regional scalG.. characteristics: steep slopes and tight soils ac­ The regionalization of problems can 1 1 ~ ex­ celerate flooding; permeable soils, marshes, pected to intensify as urban areas continue to swamps, and flood plains attenuate flooding by expand and coalesce. In virtually all urban re­ retarding runoff. Recharge of ground-water gions, the fragmented governmental ir~titu­ reservoirs is dependent upon infiltration char­ tions are ill equipped to deal with re.-rional acteristics of soils; the degree of siltation of problems. As a start towards attacking these rivers and lakes is determined by erodibility regional problems, Councils of Governments characteristics of these same soils. Minerals have been organized in most metropolitan leached from the soils by infiltrating rainfall areas. Some of these councils are assuming add chemical .constituents to the water resource, operational responsibility for certain functions and its organic composition is altered by decay­ such as transportation and waste disposf.l. Re­ ing vegetation. Water, on the other hand, also gional planning, however, is usually the central influences other natural resources. Landslides unifying activity of a typical Council of Gov­ and mudslides often result when unstable soils ernment. become saturated. Runoff helps shape the Water management provides an excellent topography of the land surface, and stream.flow example of the regional scope of urban prob­ carves valleys and creates flood plains. Water lems. Typically, water flows in and out of urban concentrates minerals in usable deposits. areas with no regard for jurisdictional boun­ Man's activities have intensified the interre­ daries. The principal source of surfac·e-·water lationship between water and the other natural supply may be located far upstream fro'll the resources. Water has been generally available area itself. Urban areas commonly are r~rved to meet the demands of urban areas. Much of by ground water withdrawn from aquifers the development, however, has been both uni­ whose boundaries do not coincide wit]' city lateral and unifunctional in approach: engi­ boundaries. Sewage effluents from s~wage neering works were designed to supply water treatment plants of cities are discharged to to the cities and to carry away the wastes. The streams, creating problems for urban areas result of this approach are apparent. Polluted downstream. These water problems require re­ rivers, rapid eutrophication of lakes, and de­ gional solutions. graded recreational and esthetic benefits of water resour.ces attest strongly to the need for INTEGRATION INTO URBAN PLANNING AND consideration of .all natural resources, includ­ MANAGEMENT ing water, in urban planning and management. Water-resources investigations have not. been traditionally considered as components of the REGIONAL APPROACH urban planning process. This fact is due in It is becoming increasingly apparent that large part to the divergent backgrounds of many, if not most, of the problems facing the water-resources scientists and urban planners. Nation's urban areas are regional in nature. The water-resources scientist, or hydrolo~:ist, is The most highly publicized problems are in the usually trained in the physical sciences (geol­ ar,eas of crime, drugs, poverty, schools, and ogy, chemistry, geophysics) or engineering, transportation, but the problems of the natural whereas his counterpart, the urban planner, environment are rapidly assuming equal im­ most likely had his training in the social sci­ portance. Problems of water and air pollution ences or landscape architecture. The divergent are extremely serious in many areas. Managing training of physical scientists and social scien­ the ever-increasing mountain of solid wastes tists has complicated the communication pro­ taxes our ingenuity. Maintaining an adequate cess necessary for incorporating water-resource

H3 information into the planning process. than 60 years are available. Most of these data With the incr·easing emphasis being placed are observations and measurements made over on quality of environment, the urban planner is a continuing period. In addition to these basic finding it increasingly necessary to understand measurements, many types of SJl ~ialized data the physical system of the region for which he and studies are available. In mr.ny cases, the is developing a plan. On the other hand, the collection of the specialized data was spurred same awareness is forcing the hydrologist to by special need and made possib 1 ~ by develop­ consider the context in which he studies the ment of specialized instrumentat:~~'ln and meas­ physical system. Water, of course, is an im­ uring techniques. Examples are data on flood portant element of this physical system. Thus, profiles, aquifer yields, stream time-of-travel, the need for a close working relation between and salt-water intrusion. More re~ently, water­ the urban planner and the hydrologist is being resources investigations projects have been recognized, and both are becoming increasingly supplying data on regional bases. Although gen­ concerned with environmental factors such as erally collected for a specific objective, they air and water pollution, flood plains, ground­ nevertheless contribute to the overall bank of water resources, sand .and gravel resources, and data vital to the appraisal of wr.ter resources unstable soils and slopes. Land-use planning is of urban areas. becoming more environmentally and resource Also needed-and available-nre hydrolog­ oriented. ically related data. For example, data on water­ Today urban planners are also using increas­ supply systems and wastewater disposal facil­ ingly rigorous analytical methods. Theoretical ities are important as a set of hydrologically research in regional analyses has evolved a sys­ related data, as are data on many other cultural tem of modeling of various combinations of developments such as locations of areas served regional development, assigning a range of dif­ by septic tanks and sewer systems and locations ferent policies and constraints, and then evalu­ of sites and types of solid-waste disposal. ating the resultant economic and functional con­ Some hydrologic information can be directly sequences. In the evaluation of viable develop­ integrated into the urban planring process; ment alternatives, the planner must be aware other information, to be useful tc the planner, of the physical system. This awareness includes must be analyzed, interpreted, and sometimes at least rudimentary understanding of hydrol­ combined with other kinds of data. ogy and other physical sciences. Just as the planner must be aware of the relation of RELATION TO PLANNil'T~ hydrologic factors to his planning, so must the The goal of the urban planner is to guide the hydrologist be knowledgeable in the processes future development and growth of cities and of urban planning. Together they must develop regions to minimize problems and optimize the thedevelopment-alternative/resource-impactre­ quality of living. Thus, the many and diverse lationships necessary for sound decision mak­ forces that create pressures for gr()wth andre­ ing. Close teamwork is necessary and requires newal of the urban environment are the prin­ joint understanding of both the resource system cipal concern of the urban planner. Guidelines and the planning process. In a sense, both the for future development are usually expressed planner and the hydrologist must extend their in a comprehensive plan that proposes the competences beyond traditional boundaries. future arrangement of uses of land, such as This, in turn, will likely lead to development .of residential, .commercial, industriaL transporta­ new dis·ciplines within both professions. tion facilities, schools, hospitals, parks, and open space. The comprehensive :r1an is based TYPES OF INFORMATION on studies of current conditions z.nd forecasts Hydrologic information has traditionally con­ of population growth, anticipated future land sisted of various types of water measurements uses, social changes, transportation, prospects including river stage, streamflow, depth to for future commercial and industrial develop­ ground water, artesian pressure head, and ment, governmental policies, and other factors water quality. Records that date back more which may influence urban development.

H4 Thus, planning is a complex and multifaceted The development of useful products involves process that attempts to integrate all the a partnership between the hydrologist and the physical, economic, social, and political impli­ urban planner and an evolution of products cations of urban development into an orderly from basic data through stages of compilation plan. Land-use planning is the part of this and interpretation to user-oriented products. larger pr·ocess that is concerned with the loca­ Figure 1 is a simplified flow diagran1 which tion and density of development of the various illustrates the evolution of such an interdisci­ space-demanding functions of urban activity. plinary effort. The effort begins with the The water-resources system is in reality a identi.fication of problems and definitio,_ of ob­ subsystem of the physical urban system. There­ jectives. The ultimate goal is improvei urban fore the planner must consider the water­ dev·elopment. This goal can be appr.oached, as resources subsystem in the broader context of shown in the diagram, by following two parallel all the other subsystems. In order for him to paths. The upper path represents the activities consider this water-resources subsystem, how­ of the urban planner, and the lower path repre­ ever, he must have information available to sents the inputs of the water-resourcP.s scien­ him in formats that he can understand and tist. Inherent in the activities of th~ urban use. Howev·er, the traditional products of the planner are all planning considerations,, includ­ hydrologist are not always easily understood ing technical, institutional, legal, and political by those involved in urban planning. items.

,------PLANNiNG PROGRAMs------~ I POPULATION AND LAND-USE INVENTORY APPRAISAL OF I I ANALYSIS INTEGRATION PROBLEMS AND I I ;:;:0-;;C-;;.;;;~;-G;;;,;:;;;-.;;-. ~.;, ;.;-N-;; OS OPPO RTU NITI ES OF PLANNING I r FACTORS PLANNING i IMPROVED IDENTIFICATION AND URBAN OF PROBLEMS f----+ MANAGEMENT DEVELOPMENT

t ALTERNATIVES I I BASIC DATA AND l PROBLEM ORIENTED ANALYSIS I WATER- TRANSlATION I y RESOURCES I TECHNICAL INFORMATION' AND INTERPRETATION I APPRAISAL TO PLANNING I I I WATER-RESOURCES INVESTIGATION ------~

FIGURE !.-Simplified flow diagram of the urban planning process showing the interrelation of water-resources investigations and urban planning.

The parallel paths, however, are not mutually use and planning functions. Although only exclusive. At any point in the water-resources hydrologic factors are listed, geologj c, topo­ investigation, available information can be in­ graphic, and demographic inputs are necessary troduced into the planning process. Som·e basic for each successive step in the develo:rment of data and technical information, for example, the comprehensive planning maps. can be used at all stages of planning. Similarly, each step in the formulation of a plan for urban HYDROLOGIC ELEMENTS OF UF BAN development can feed back to the water­ WATER APPRAISALS resources program to enable a continuing reap­ Appraisals of urban water problem·~ can be praisal of the program to insure that this com­ both simple or complex. Often may types of ponent of the planning program remains hydrologic data are needed for appraisals of relevant. but one urban water problem. For sone prob­ As the planning ·efforts progress, the analyses lems, however, specific types of data are needed. of the basic hydrologic data must of necessity A water-resource appraisal, therefore, must be become more complex. Table 1 shows the designed with care, and the data and informa­ sequence of hydrologic analysis applied to land tion available must be evaluated in terms of

H5 TABLE 1.-Sequence of hydrologic analysis applied to land use and planning functiO?'~ [Number of variables required for synthesis increases -+ J

3d Gen ~ration, compre­ Basic data Basic maps and 1st Generation, 2d Generation, translation hensive planning sections interpretive planning to planning maps Aquifier data Water yield Recharge maps AIIowable septic tank density Ultima+-"! design Ground-water levels Water-level maps Water-availability maps Water-use density Land-u~e compatibility Streamflow measurements Hydrographs Permeability maps Landfili sites Alternate choice Water-quality data Streamftow maps Poiiution susceptability Foundation suitability Precipitation Weii location maps Transmissivity Evapotranspiration Depth of water Drainage maps Water-quality maps Analog-digital models

specific objectives. A unifunctional approach AN EVALUATION MATRIX that will provide answers to a single problem Although a critical need for wF.ter-resource may be a useless input to other urban water information for urban planning hP.s developed, problems. urban planners are not generally able to iden­ RELATIONSHIP OF HYDROLOGIC DATA TO tify the hydrologic parameters that are needed URBAN PROBLEMS for specific water problems. To help bridge this Urban water problems can be broadly classi­ gap, a water-resources evaluation matrix has fied into nine general categories, which are been developed. The matrix provides a means adequate for broad-scale planning. These urban for determining the relative importance of water problems, in turn, relate to other urban water-related problems and for identifying the problems, and appraisals from a water-oriented data needed to evaluate these prolJ lems for the viewpoint must also consider the relation to purpose of urban planning. the general problems. The matrix (pl. 1) lists nine fllbject cate­ For example, disposal of solid wastes is a gories in which water-related urb~.n problems major problem of urban areas, because, in ad­ may occur. Although all categori& are not ap­ dition to health and logistic problems, pollu­ plicable to every urban area, in ag~regate they tion is a serious consideration. Water entering represent those urban problems that are either the waste material from rainfall or other water oriented or water dependent. In some sources leaches organic and inorganic materials areas it is possible that a peculiar water­ from the waste. This contaminated water tends oriented problem may exist. This problem can to move toward the ground-water reservoirs easHy be accommodated in the matrix by the and then to streams. Aquifers and streams can addition of another column. be readily polluted by this process. The matrix also lists 51 possible. data inputs The hydrologic aspects of the sanitary land­ for evaluation of the problem areas. The inputs fill problem, while only a small part of the include the standard types of basic hydrologic overall problem, are nonetheless complex. If data as well as information based on interpre­ landfill sites are to be selected to minimize tation and analysis of these data. In addition ground-water pollution, detailed hydrologic in­ to water-resource items, the list includes the formation is needed on the ground-water sys­ interfacing factors of climate, land, and cul­ tem. Similarly, information on floods is re­ ture. These factors, especially the cultural, are quired if the wastes are to be kept from direct essential to any appraisal of urban influences contact with water bodies. Land characteristi¢s on water resources. such as types of soils and slopes are also re­ quired, as are data on climate and existing The matrix aids in the development of re­ cultural features. The problem can only be source evaluation in two ways. First, by pro­ assessed properly by considering pertinent moting interdisciplinary discussior. it leads to hydrologic information in conjunction with a mutual understanding of the water-related climatic, land, and cultural resources informa­ problems. Second, it serves as a checklist for tion in terms of the total impact on the entire determining the data needs for evaluation of resource system. each problem.

H6 In the development of a comprehensive pro­ related problems that the planner faces. Second, gram of water-resource evaluation, ranking of it provides the hydrologist with a similar the relative importance of information needs is appraisal of the problems involved in ewlluating necessary in order to establish overall program the impact of the water resources on tl'~ urban objectives. The matrix lends itself readily to problems. Third, it provides for a realistic such ranking while simultaneously providing consideration of water resources as an integral the means for relative ranking of importance part of urban planning and management. Most of data inputs for each problem area. The rank­ significantly, it provides a means of ing of the importance of the information needs communication between the hydrologist and the of the planners is the first step and requires planner. both dialogue and consensus between the plan­ The obvious development from the n~atrix is ners and the hydrologists. A suggested format a work program that encompasses the full scope -one developed for the example presented in of water problems in a set of related work ele­ this circular and used in subsequent appraisals ments. In any metropolitan area, it is n'lt likely -is a relative ranking on levels: a rank 3 is that the entire program could be under+aken in most important, a rank 2 is moderately im­ a single effort because of the magnitude of the portant, and a rank 1 is least important. Those program. However, high-priority worl{ items having no relevance are excluded and may be can be readily identified from the matrix and considered as having a value of zero. undertaken in ord·er of priority. The matrix When the information needs have been also identifies the overall data requirements for ranked, the matrix can be used to determine the each data element and thus insures that the relative importance of each data input to that total need for data is not overlookec1 in the particular urban problem. This is accomplished consideration of one element of t:l1e work by rankjng each data input as it relates on the program. same scale (3 to 1) as the information need. WASHINGTON-BALTIMORE STUDY CASE Again, a value of zero applies to input data that are not relevant. The rank assigned is Plate 1 shows the application of the evalua­ recorded in the lower left section of each box, tion matrix to the Washington-Baltimor~ urban as indicated on plate 1. A comparative value area. Because of its growth rate and vr.dety of can then be assigned to each data component water problems, this area makes an excellent by multiplying the indicated rank of the urban case study. The area, shown in figure 2, centers problem and the assigned rank of the data around the standard metropolitan statistical requirement. This value is recorded in the areas (SMSA's) of Washington and B2ltimore. upper right section of each box. The sum of In addition to this core area, three rapidly the values in the upper right section of a row growing Maryland counties are included. To­ of boxes is an index of the relative needs of gether they form an area of 4,530 square miles hydrologic data for a total water-resource stretching eastward from the Blue Ridge evaluation. Mountains to the Chesapeake Bay and south­ Upon completion of the matrix, the hydrolo­ ward from the Pennsylvania State lin~ to the gist can determine the availability of data to big bend in the Potomac River. meet the requirements as identified by the Although the central cities had a slight de­ matrix. The need for data-collection programs crease in population during 1960-70, rapid can then be determined, and the relative ease growth has occurred in the peripher~l areas of such data collection can be assessed. Prior­ within a 25-mile radius of the city centers. ities on work elements can be assigned to pro­ Development patterns in the subur':ls have vide the planner with maximum information tended to be erratic, resulting in srrawling in minimum time. growth during which large areas have. quickly Thus, the matrix provides both the hydrolo­ developed without regard to urban suitability. gist and planner with an appraisal of problems The Washington-Baltimore area is a repre­ related to water in the urban environment. sentative slice of the physical environment of First, it provides an appraisal of the water- the Atlantic seaboard. The geology is complex

H7 800

PENNSYLVANIAt

0 so 100 MILES

FIGURE 2.-Map showing the Washington-Baltimore urban area. and has strongly influenced the land-use pat­ Natural resources are also profoundly dif­ terns, as well as the availability and develop­ ferent on opposite sides of the Fall Line. For ment of natural resources. The outstanding example, the Coastal Plain has abundant natural feature is the Fall Line, which sepa­ ground water both for domestic and industrial rates the hard rocks of the Piedmont from the use. In the Piedmont, however, ground-water unconsolidated or semiconsolidated sediments supplies are barely sufficient for domestic use of the Coastal Plain. The Fall Line follows a and large developments must dep~nd on sur­ low rise of the land trending northeast through face-water sources. Washington and Baltimore. Since coloni~l The hydrology of the W.ashingtC'n-Baltimore times, the Fall Line has divided the region into region is dominated by the Potomr~ River and two different economic areas. For many years the Chesapeake Bay. Urban planning for the the flatter lands of the Coastal Plain were region must provide for continued development largely planted in tobacco. The rolling hills of of these water bodies while simultaneously pro­ the Piedmont, on the other hand, were dairy tecting them from further degredation. and stock-raising country. Agricultural uses Consultation with the staff of the Regional still occupy the largest areas, but the pattern Councils of Governments and oth~r planning is rapidly changing with urbanization and in­ agencies in the area resulted in rB pid identifi­ dustrial growth. cation of water supply, pollution Joading, and

H8 the estuaries as the critical wate-r-related urban The great need for data on water quality and problems. Erosion and sedimentation, existing sources of pollution is consistent with recent water quality, and urban drainage were further trends in urban water problems. Sewabe and identified as serious urban water problems. Of waste disposal works historically have been lesser importance, but of some concern, were designed to remove wastes rather than t-o pro­ the water-related aspects of solid-waste dis­ tect water quality. A burgeoning population posal and esthetics. Land deformation was not and an affluent society have produced more deemed to be a problem. wastes than streams can assimilate, and the E.ach ranking (pl. 1) was derived by inte­ public is now demanding changes in the ap­ grating resource knowledge with knowledge of proach to waste disposal. Water pollution is the present urban conditions and future plans now the most apparent and the most important for urban growth. The type of considerations aspect of urban water-resource managerr~nt. that went into the ranking process can best be illustrated by a few examples. SUMMARY AND DISCUSSION IThthe Washington-Baltimore area, municipal In the past, land was plentiful and res':lurces water supply is .a critical problem for the entire were abundant. Both were taken for granted, Washington sector. The municipal supply is and their uncontrolled development wa.s for taken from the Potomac River, and in recent many decades the accepted way of urban years at times the demand has almost equaled growth. Urban growth sprawled acro~s the the flow in the :river. Although consideration is landscape without much regard for the ratural being given to use of the upper estuary as an resources. Growth for the sake of growth be­ auxiliary supply, upstream reservoirs will prob­ came the goal, and cities competed openl:T with ably have to be developed in the Potomac basin. each other for industry and people. Ind~ed, if Several plans have been proposed, but all are resources were considered, it was in terms of controversial ; as yet no single plan is generally exploitation rather than environmental consid­ acceptable. The major scope and the critical and erations. unresolved nature of the problem was the basis The large population shifts following World for giving regional water supply a value of 3. War II brought about unprecedented urban The problem of pollution loadings was iden­ growth. Gradually, through the 1950's and into tified as critical (3), while existing water qual­ the 1960's, the price of neglect of our resources ity was deemed serious (2). Although knowl­ became apparent. The environment ~as rapidly edge of existing quality is necessary to planning, becoming despoiled. Untreated sewage fr1m en­ it is the pollution loadings that primarily con­ tire cities was discharged to streams, which trols not only the present but future water became open sewers. Floods became more fre­ quality. The pollution loadings category was quent and more intense as urban runoff was thus ranked as a more critical problem. Exist­ accelerated from paved and roofed areP.s. To­ ing water quality is, nevertheless, a very im­ day, water problems-especially those of pollu­ portant problem in the area, so it was given tion-besiege every urban area. In some ·areas a rank of 2. they rank along with social and economic issues The matrix analysis of data needs indicates as a major urban problem. that the most important inputs are the cultural Indeed, the abuse of our natural resources, factors of population and land use. Although especially in urban areas, has brought about a this might appear startling to the hydrologist, peaceful revolution over protection of cur en­ one must recognize that water is only one of vironment. This attitude, in turn, has brought many resources that an urban planner must about a new approach to urban planning-an consider. The individual resource evaluations approach in which consideration of the natural must be integ-rated, and to achieve this, each resources, especially water, is a significant fac­ evaluation must be made in relation to the tor. To be effective, the new approach requires pivotal fa·ctors of population and land use. an input of new types of data to urban planning Hence, these factors serve as the essential basis and ultimately to the decision-making process. for any urban water-resource evaluation. Traditionally water-resources data have not

H9 been interpreted or presented by the hydrolo­ has the responsibility to conside:r such data in gist in a manner whereby it can be readily used making decisions. by the urban planner. And traditionally, the This circular has attempted to develop a urban planner has utilized hydrologic data only rational approach to ·consideration of water re­ in terms of water supply and waste disposal. sources in the planning and management of our The new environmental approach to urban urban environment. The utility of the approach, planning, however, requires a meaningful input however, is dependent upon the ralevance of the of water-resources information. Developing studies and the approapriatenese of the presen­ this input requires continuing communication tation of results. Hydrologic data may be ana­ and contact between the urban planner and the lyzed in many ways. Yet to be relevant, the hydrologist in order to insure the relevance of data must be analyzed in a way that takes into the data. For example, the hydrologist generally consideration the multifaceted aspects of the has at his disposal information on river stages, entire planning process as well as the restric­ but until recently he has not translated these tions imposed by the managem~nt aspects of data into flood-inundation maps that planners governmental jurisdictions. The analysis must can use to prevent excessive urbanization of consider alternatives, and the alternatives must flood-prone areas. On the other hand, planners be viable. frequently are unaware that such basic data The hydrologist has the respor.':\ibility to pre­ as river stages can provide them with an effec­ sent ·a strong documentation of the water re­ tive planning tool to limit encroachment upon sources of the area. He must present both the flood plains. Recognition of the need for flood­ advantages and disadvantages, from a hydro­ inundation information or for means of con­ logic standpoint, of viable alternatives. He verting flood-stage data. into flood-inundation must present the current assessment of the information has resulted from meaningful water resource in a clear and firm manner. He dialogues between planners and hydrologists. must clearly document the co~sequences of The proper interpretation of water-resources alternative actions. In doing this, he must work data is not only a valuable adjunct to long-range closely with and-perhaps even more-under­ planning, it is also useful to the urban planner stand urban planning procedur£.~, This is not I in making day-to-day decisions. Such day-to­ an easy process; experience has shown that, ex­ day decisions as the design of urban storm cept in a few cases, communication between the drainage, location of sanitary land,fills, and per­ hydrologist and the planner has been one of mits for septic field drainage all require ade­ parallel monologues rather than a meaningful quate information on regional water resources dialogue. The new awareness of our environ­ that can be obtained from basic hydrologic data. ment, however, has provided botl' the need and Today, a wealth of water-resources data is the motivation for better comn1unication be­ tween the hydrologist and the plgnner. available to assist the urban planner in both The final decision on the management of the day-to-day and long-range decisions. These water resource rests, of course, with the plan­ data, however, must be interpreted and supple­ ner. He has the responsibility to vreigh the facts mented where necessary to provide an adequate presented by the hydrologist. In the total plan­ basis for decision making. If the environment ning process, water resources must be con­ is to be considered in urban planning, the sidered along with all other resources-social, hydrologist has the responsibility to see that economic, cultural, and physical. If the planner water-resources data are available to the urban is aware of the hydrologic consequences of his planner in usable form, and the urban planner decision, the hydrologist has ful'Uled his role.

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