PRECIPITATION AND WATER-TABLE EFFECTS ON AGRICULTURAL PRODUCTION AND ECONOMICS

The sensitivity of irrigated agriculture to water-table fluctuations a nd agroeconomic parameters was analyzed in the context of long-term cl imatic variability. Capillary rise was modeled as a function of soil m oisture content and depth to the water table. The capillary rise model was used to define the sensitivity of soil moisture depletion, actual evapotranspiration, and agricultural benefits to changes in water-tab le depth. Water-table fluctuations had a pronounced effect on root-zon e soil moisture, irrigation water use requirements, and agricultural b enefits. An economic analysis was performed to determine the sensitivi ty of site-specific irrigated potato production in the San Luis Valley given the potential changes in available irrigation water supply and agroeconomic parameters. Agricultural benefits were found to be highly sensitive to production costs variations, to deviations of crop marke t prices from their mean values, and to available irrigation water sup ply.