Cost/Benefit Analysis for the ASVT on Operational Applications of Satellite Snow-Cover Observations
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NASA TP ' ?f 1822- 1,'"' v. 7 I c.1 I December 1981 Applications Systems Verification and Transfer Project Volume VII: Cost/Benefit Analysis for the ASVT on Operational Applications of Satellite Snow-Cover Observations P. Castruccio, H. Loats, D. Lloyd, and P. Newnian F 1 i TECH LfSRARY KAFB, NM 1 NASA Technical Paper 1828 1981 Applications Systems Veritication and Transfer Project Volume VII: Cost/Benefit Analysis for the ASVT on Operational Applications of Satellite Snow-Cover Observations P. Castruccio, H. Loats, D. Lloyd, and P. Newman Ecosystems International, Inc. Gambrills, Maryland National Aeronautics and Space Administration Scientific and Technical Information Branch I ABSTRACT The results of the OASSO ASVT's have been used to estimate the benefits accruing from the added infomation available from satellite snowcover area measurement. Estimates of the improvement in runoff prediction due to addition of SATSCAM have been made by the Colorado ASVT personnel. The improvement estimate is 6-10%. Data were applied to subregions covering the Western States snow area amended by information from the ASVT and other watershed experts to exclude areas which are not impacted by snowmelt runoff. Benefit models were developed for irrigation and hydroenergy uses. Results of the benefit estimate for these major uses yielded a yearly aggregate of 36.5M. Cost estimates for the employment of SATSCAM based upon the Colorado ASVT results and expanded to the Western States totalled $505K. The benefit/cost ratio thus formed is 72:l. Since only two major benefit contributors were used and since the forecast improvement estimate does not take into account future satellite capabilities these estimates are considered to be conservative. The large magnitude of the benefit/cost ratio supports the utility and applicability of SATSCAM. Future. development in the use of SATSCAM in computer models specifically tailored or adapted for snow inputs such as those developed by Leaf, Schumann, and Tangborn, and Hannaford will most certainly increase the use and desirability of SATSCAM. iii I I1 I I I1 I1 I lllIlIlllIIlllIlllll~1llll1l11l11l11 CONTENTS PAGE ABSTRACT ................................ iii INTRODUCTION ............................. 1 BACKGROUND .............................. 1 Arizona ASVT ............................ 4 California ASVT ................; ......... 5 Colorado ASVT ............................ 6 Pacific Northwest ASVT ....................... a BENEFIT DERIVED FROM IMPROVED INFORMATION .............. 9 Estimation of Upper Bound Value of Snowmelt Water Used for Hydroelectric- Energy Production ................ 12 Estimate of the Upper Bound Benefit of Snowmelt Water Used- for Irrigation ............................. 15 THE ECONOMIC IMPACT OF IMPROVED RUNOFF FORECASTING .......... 15 DEVELOPMENT OF SNOW.FORECAST IMPROVEMENT BENEFIT MODELS ........ 17 Irrigation Benefit Model ...................... 17 Computerization of Irrigation Model ................. 32 Data Base Development ....................... 33 Improvement in Streamflow Accuracy Due to SATSCAM ........ 37 Irrigation.. Benefits ........................ 37 Hydroenergy Benefit Model ..................... 43 Computerization of Hydroenergy Model ................ 49 Data Base Development ....................... 49 Hydroelectric Energy Benefit .................... 50 SATSCAM IMPLEMENTATION COSTS ..................... 59 V CONTENTS PAGE SUMMARY AND CONCLUSIONS ...................... 60 Limitations of the Use of SATSCAM Indicated by the ASVT's .... 61 Summary of the Assessment of Irrigation Benefit ......... 61 Summary of the Assessment of Hydroelectric Energy Benefit .... 67 REFERENCES. ............................ 72 CREDITS AND ACKNOWLEDGEMENTS ................... 74 vi APPENDIX A Description_- of- the .__Hydrologic - Regions and Related Snow Survey Forecast Points APPENDIX B Description of Surface Water-Irrigated Areas in the Western U.S. (1975). and Estimates__ -.Crop Yalue Per- Acre (J976) APPENDIX C Hydroel ectEi c Energy- Data Base : Average Annual Hydroelectric Energy Generation Unit Production Costs Average Unit Revenues for the Sale of Primary and Secondary Energy APPENDIX D Computer_- Programs__ - Used for Data Storage and Data__ Reduction/Analysis APPENDIX E Assessment- -. of Relative Tmportance_- of- --Snowmelt - CThe Snow Fraction) APPENDIX F of Future.~ .. Reservoirs vi i COST/BENEFIT ANALYSIS FOR THE OPERATIONAL APPLICATIONS OF SATELLITE SNOWCOVER OBSERVATIONS (OASSO) By Peter A. Castruccio, Harry L. Loats, Jr., Donald Lloyd, Pixie A. Newman INTRODUCTION It is almost a decade, dating from the early 1970's, that satellite technology has been capable of providing relatively high quality images on a frequent enough basis to indicate to hydrologists that a possibility for gathering data on snowpack area was practical. Both the techniques for measuring the snowpack area and its applications for improving seasonal runoff predictions have been demonstrated (Reference 1,2,3). As a result, an Application Systems Verification and Transfer (ASVT) program was established by NASA, the major thrust of which was to extend these research efforts into the realm of operational runoff forecasting. The operational employment of satellite snowcovered area measurement (SATSCAM) to runoff forecasting has been evsluated at four sites strategically located throughout the Western United States. To supplement the ASVT technical evaluations, NASA initiated a study to determine the costs and benefits of operationally applying SATSCAM in this region. BACKGROUND An effort to analyze the value of the improvement of water resources operations attributable to satellite data inputs was initiated by the Goddard Space Flight Center in mid-1976. The program was structured around the findings to be obtained from four ASVT (Applications Systems Verification and Test) sites situated within the 11 Western States. The primary objectives of the investigation carried out at the four ASVT test sites were: 1) to evaluate the operational capability for use of satellite imagery in mapping snowcover area within the test basins; 2) to develop techniques and procedures for systematically monitoring snowcover from re- motely sensed imagery; and 3) to perfect methods to incorporate satellite snowcover area measurements into operational streamflow forecasts. Table 1 lists the ASVT sites for which test data has been collected. These sites/areas include the wide spectrum of geographic and hydrologic diversity necessary to evaluate the general utility of SATSCAM to operational stream- flow forecasting. Figure 1 indicates the locations of the Snow ASVT study basins. The following is a brief summary describing each snow ASVT test site, its activities and results. * Table 1 Snow ASVT Test Sites ARIZONA Cognizant Personnel : H.H. Schumann - U.S. Geologic Survey (USGS); W. Warskow; E. Kirdar - Salt River Project (SRP) Key Watersheds : Prinicpal Applications: Power; irrigation; water supply; flood control CALIFORNIA Cognizant Personnel : A.J. Brown - California Department of Water Resources (Calif. , DWR); J. Hannaford - Sierra Hydro tech Key Watersheds: Feather; Upper Sacramento; San Joaquin; Kings; Kern; Kaweah; Tule Prinicpal Applications: Power; irrigation; flood control COLORADO Cognizant Personnel : J. Washicheck, B. Shafer - Soil Conservation Service (SCS); J. Danielson - Colorado Division of Water Resources (CDWR); B. Hansen - Bureau of Recreation (BuRec) Key Watersheds : Rio Grande (above Del Norte); Conejos (above Mogote); Culebra (above San Luis); San Juan (above Carracus) ; Arkansas (above Sal ida) Principal Applications : Power, i rri gati on IACIFIC NORTHWEST Cognizant Personnel: J. Dillard - Bonneville Power Administration (BPA) B. Thomas - Corps of Engineers (COE) Key Watersheds: Boi se; C1 earwater; Kootenai ; Upper Snake 3 F1 athead ., Pri nci pal Appl ications : Power, flood control , irrigation 2 SCALE 1 :14,000,000 Figure 1. Locations of snow ASVT study basins of the Eleven Western States 3 Arizona ASVT The Salt and the Verde River basins, located in central Arizona, were evaluated by the Arizona Snow ASVT. The elevation of these basins range from 1,325 to 12,670 feet (400-3,900 m) above sea level. The mean annual precipitation is 10-25 inches (250-650 mr4\).. The snowpack below 7,000 ft. (2,100 m) is generally thin and transient, energy input for snowmelt is intense, and significant melt is possible throughout the snowmelt season. Since tree cover is sparse and cloudcover recurrence is low, near optimum satellite observing conditions exists over these basins. Snowcover data were obtained from aerial snow flights, Landsat imagery, SMS/GOES imagery, and NOAA/NESS snowcover maps. The ASVT personnel used these sources in combination in order to obtain the maximum amount of available information. Flight data was of particular value when clouds obscured satellite observation of the snowpack. Aerial observation continuedto be a valuable method of assessing snow depth and runoff conditions. However, the availability of frequent satellite snowcover observations has greatly reduced the necessity for frequent aerial reconnaissance flights. Snowcover data was primarily extracted from Landsat imagery, both Band 5 and Band 7. A density slicing technique was utilized which enabled the operator to select snow reflectance thresholds, thereby distinguishing snowcovered from non-snowcovered areas. Color additiveviewingwithwatershedmasks was also employed. The zoom transfer scope was used for the transposing of data