A REEVALUATION OF THE GROUND WATER BUDGET FOR LAS VEGAS VALLEY, NEVADA, WITH EMPHASIS ON GROUND WATER DISCHARGE1

Publisher Website
Google Scholar
Abstract
An essential component to the ground water budget for the Las Vegas Valley (LVV) in southern Nevada is discharge from the ground water system. Discharge for the LW has been based on estimates made more than 50 years ago of 35,524,224 m3 per year as evapotranspiration (ET) and 0 m3 per year as subsurface outflow. Newly published values for recharge based on a more robust data set (70,308,360 m3) indicate a large imbalance associated with the earlier discharge estimates, providing the basis for the reevaluation conducted in this study. ET estimates in this study, as opposed to previous studies, were assigned a range in values that included an approach that assigned higher weight to the unique soil, plant, water, and climatic conditions that existed in predevelopment (1905) LW. The earlier discharge estimates also assumed that the basin was hydrologically closed; however, based on our evaluation, a range in yearly discharge by subsurface outflow from 1,480,176 m3 to 19,735,680 m3 could be assigned. Likewise, a range in yearly ET from 20,475,768 m3 to 78,819,372 m3 could be assigned. Based on newly published recharge values, closure can only occur if higher values are assigned to both the subsurface outflow and/or ET components of ground water discharge. We cannot provide a complete water balance closure with our ground water discharge estimate of 64,140,960 m3. However our reevaluation gives support to the higher recharge estimates and provides the rationale for future studies to be conducted based on a more rigorous scientific assessment.