EXPLORING THE EFFECT OF CLIMACTIC PERTURBATIONS ON BASIN SCALE HYDROLOGY IN THE INDIAN WELLS VALLEY

Recent U.S. population statistics estimate that by 2050, the southwestern United States will experience a population growth of roughly 70% (Garfin et al. 2014). This growth exemplifies the importance of groundwater resources in a region where many communities are already reliant on groundwater as a primary source of potable water. To balance California’s need for food and energy with the region’s water demands, future hydrologic perturbations need to be considered. When compared to more temperate, costal, or urban areas of California, the coupled nature of the energy, food, and water nexus is particularly apparent within the Indian Wells Valley (IWV). The IWV is a rural desert region in the rain shadow of the southeastern Sierra Nevada whose main constraints with respects to food and energy development are related to water quantity. Increasing global temperatures are driving climactic changes projected to alter aspects of the hydrologic cycle within the IWV, including the probability of extreme climactic events such as the 2014 California drought. What made the 2014 California drought so unique was not exclusively the absence of precipitation, but the high temperatures which accompanied the drought. To assess the hydrologic impact of future coupled climatic events in which multiple hydrologic extremes may occur simultaneously, we look to quantify the anthropogenic and climactic perturbations in the region, and their ultimate feedbacks on the hydrologic system. By leveraging a MODFLOW groundwater model of the IWV and downscaled predictions of perturbations to climatic variables, we can assess several key questions relating to potential groundwater availability under a changing climate. Specifically, by varying the climactic variables that control evapotranspiration (ET) and mountain front recharge (MFR) within the basin, we project an increasing fraction of both soil moisture and shallow groundwater being lost to evapotranspiration. Additionally, changes in the seasonality of precipitation and increased temperatures are projected to cause a net decrease in mountain front recharge, and a seasonal signal in both recharge and water availability for the IWV. Changes in the seasonal availability of groundwater, may have significant impacts for future economic and agricultural development within the basin.