AbstractsGeography &GIS

The Rio Grande Valley from South Fork to Del Norte, south-central Colorado, comprises a distinct hydrologic system with reasonably well-defined boundaries. The valley, located on the east flank of the San Juan Mountains, contains a twelve and one-half mile reach of the Rio Grande and has an area of 19,400 acres. A hydrologic budget developed for the alluvial aquifer of the valley for the period April 1, 1970, to March 31, 1971, indicates an inflow of 75,000 acre-feet, no storage Change, and an outflow to the Rio Grande of 25,000 acre-feet with a standard deviation of 5,000 acre-feet. The alluvial aquifer responds rapidly to a springtime recharge pulse and the water table rises from a minimum level at the end of Mardi to a maximum in early July. A hydrologic budget for this period in 1970 indicates a Change of storage of 23,000 acre-feet and a storage coefficient of 0.26.