Estimating recharge distribution by incorporating runoff from mountainous areas in an alluvial basin in the great basin region of the southwestern United States

A method is described to estimate the distribution of ground water recharge within hydrographic basins in the Great Basin region of the southwestern U nited States on the basis of estimated runoff from high mountainous areas a nd subsequent infiltration in alluvial fans surrounding the intermontane ba sins. The procedure involves a combination of Geographic Information System (GIS) analysis, empirical surface-runoff modeling, and water-balance calcu lations. The method addresses the need to develop and incorporate constrain ts on the distribution of recharge in regional-scale ground water flow mode ling of arid and semiarid environments. The conceptual approach and methodo logy were developed for Crescent Valley, Nevada. However, the concept and m ethod are generally applicable to any region where excess precipitation in upland areas is conveyed to lower elevations before it infiltrates to recha rge the ground water system. Application of the procedure to a ground water flow model of Crescent Valley appears both qualitatively and quantitativel y to result in a more accurate representation of actual recharge conditions than might otherwise have been prescribed.