WSP02633 - Laserfiche WebLink

Home Browse Search

fl~'~9"~ ('jP~~ .~~) " ')"./" ,JU . . meter studies conducted at the Navajo Indian Irrigation Project (NIIP). Tempera- ture and precipitation conditions within the San Juan River basin vary primarily because of elevation differences. Temperature generally decreases with a gain in elevation while precipitation generally increases with a gain in elevation. Weather conditions at the Pagosa Springs weather station (Elev. 7105) are consid- ered generally representative of the irrigated areas in the San Juan River basin with drainage elevations above 7000 feet. For irrigated areas with average elevations below 7000 feet, climatic data from the Ignacio weather station (Elev. 6460) are considered more representative. The average mean monthly temperature and precipitation data adopted for the study period are as follows: . . . MAY JUN JUL AUG SEF OCT Fagosa Springs Temperature (OF) 49.0 57..5 64.4 62.2 55.1 Precipitation (in. ) 1.2 0.7 1.7 2.5 1.8, Ignacio Temperature (OF) 52.5 61.7 68.3 65.7 58.4 48.4 Frecipitation (in. ) 1.0 0.5 1.5 1.7 1.3 1.7 . . A portion of the precipitation occUlTing during the irrigation season was estimated to be effective in reducing irrigation requirements, based on use of the modified Blaney-Criddle procedure for calculating effective precipitation. For irrigated areas above 7000 feet, crop water consumption generally occurs from May through September. The potential consumptive use of irrigation water for these areas was estimated to be 1.7 acre-feet per acre, provided that a sufficient irrigation supply is available when required by the crops. For irrigated areas below 7000 feet, consumption of water by crops generally occurs from May through October. The potential consumptive use of irrigation water for areas below 7000 feet was estimated to be 2.2 acre-feet per acre. Monthly summaries of temperature and precipitation at the Fagosa Springs and Ignacio weather stations are presented in Appendix D. Monthly summaries of the potential consumptive use of irrigation water are also presented in Appendix D. . . . -19- .