Irrigation Conveyance System Inventory Summary Bear River Basin Idaho Utah Wyoming

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ISBN 13 :
Total Pages : 66 pages
Book Rating : 4.:/5 (896 download)

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Download or read book Duty of Water Under the Bear River Compact written by and published by . This book was released on 1989 with total page 66 pages. Available in PDF, EPUB and Kindle. Book excerpt: A three state cooperative study was conducted from 1982 through 1987 by Utah State University and the Universities of Idaho and Wyoming for the Bear River Commission to help determine a duty of water under terms of the Bear River Compact. The primary focus was field research in the Upper and Middle Bear River Basin to determine consumptive use of high elevation irrigated meadows and to develop a methodology to estimate historical depletions. Three sites were selected for the field study; Hilliard Flat south of Evanston, Wyoming (elev. 7550 ft), north of Randolph, Utah (elev. 6280 ft), and north of Bear Lake near Montpelier, Idaho (elev. 5928 ft). Lysimeters were located in irrigated meadow at each of these sites and electronic weather stations were placed nearby. The major portion of the field work began in the spring of 1983. Seasonal crop water use for irrigated meadow varied from 15.8 to 32.5 inches among the three sites for 1984 through 1987 seasons. Crop water use from the lysimeters was used to calibrate empirical evapotranspiration (Et) equations. A modified Penman equation best matched measured Et values for the three sites across years when used with crop coefficients derived for those sites. There was more variation across sites or between years with other empirical methods, such as SCS Blaney-Criddle equation. Sufficient data from the electronic weather stations for using the Penman equation were available only for the 1982-1987 period. Thus, to complete the historical sub-basin depletion calculations, equations based on air temperature data could be considered. The modified Penman equation (Kimberly, Idaho, calibration) was used to determine monthly consumptive use values where sufficient data were available in the various subbasins; this was then used to calibrate the simpler empirical methods to estimate Et. Depletion was calculated as the water year less the sum of carry over soil moisture and effective summer precipitation. The SCS Blaney-Criddle equation, with calibrated crop coefficients and monthly temperature and precipitation data available from the NWS weather stations, was used to estimate Et and historical depletions for each of the 10 subbasins for water years 1976-1987.