Current ground-water use is required for the High Plains Regional Aquifer-System Analysis. In response to this need, a sampling approach was developed to estimate water pumped for irrigation on the High Plains during 1980. Pumpage was computed by combining application estimates with mapped irrigated-acreage information. Irrigation application (inches of water applied) was measured at 480 sites in 15 counties in the High Plains during the 1980 growing season. The relationship between calculated Blaney-Criddle irrigation demand and measured application was used to estimate application for unsampled areas of the High Plains. Application estimates multiplied by irrigated-acreate estimates, compiled from Landsat-satellite imagery, yielded the volume of ground water pumped for irrigation. The estimate of ground water pumped for irrigation in the High Plains during 1980 and 18,902,000 acre-feet for 13 ,715,000 irrigated areas. The sampled application data were evaluated for significant trends. The application was greater for crops requiring more water such as corn and hay and less for crops such as sorghum, grain, and cotton. The data showed greater application for flood-irrigated systems than for sprinkler-irrigation systems. Areas of the High Plains with thin saturated thickness tended to have a smaller average discharge per well, fewer irrigated acres per well, and a predominance of crops requiring less water crops. (USGS).
