Implications of Prospective Climate Change for Groundwater Recharge in the Western United States

Wednesday, 17 December 2014: 2:15 PM
Thomas Meixner1, Andrew H Manning2, David A Stonestrom3, Hoori Ajami4, Diana M Allen5, Kyle Blasch6, Andrea E Brookfield7, Christopher L Castro1, Jordan F Clark8, Alan L Flint9, Kirstin Neff10, Rewati Niraula1, Matthew Rodell11, Bridget R Scanlon12, Kamini Singha13 and Michelle A Walvoord14, (1)University of Arizona, Tucson, AZ, United States, (2)USGS Colorado Water Science Center Lakewood, Lakewood, CO, United States, (3)USGS, Baltimore, MD, United States, (4)University of New South Wales, School of Civil and Environmental Engineering, Sydney, NSW, Australia, (5)Simon Fraser University, Burnaby, BC, Canada, (6)USGS Montana Water Science Center, Helena, MT, United States, (7)Kansas Geological Survey, Lawrence, KS, United States, (8)University of California Santa Barbara, Santa Barbara, CA, United States, (9)USGS California Water Science Center Sacramento, Sacramento, CA, United States, (10)Organization Not Listed, Washington, DC, United States, (11)NASA/GSFC, Greenbelt, MD, United States, (12)Univ Texas Austin, Austin, TX, United States, (13)Colorado School of Mines, Golden, CO, United States, (14)USGS, Denver, CO, United States
Groundwater accounts for 25% of the United States’ total water supply. Despite this importance, research efforts related to the impact of climate change on water resources have focused on surface water projections. Here we present results from a United States Geological Survey John Wesley Powell Center Group that synthesized current knowledge on groundwater recharge and the impact of climate change on recharge across the western US (west of 100o longitude). The specific aquifers considered included the High Plains Aquifer, San Pedro basin, Death Valley regional flow system, Wasatch Front aquifers, Central Valley Aquifer, Columbia Plateau Aquifer system, Spokane Valley-Rathdrum Prairie Glacial Aquifer, Williston basin and a regional overview of research on mountain aquifer systems. Combining existing studies on projected climate-change effects on recharge (available for half of the chosen systems) with expert knowledge of the remaining systems, several key patterns emerge across the region. First, our estimates indicate declines in recharge across the southern aquifers of 10-20% on average but with a wide range of uncertainty that surrounds zero change. Second, the northern tier of aquifers will likely see no change to slight increases in recharge. Third, mountain system recharge is expected to decline across the entire region due to changes in winter precipitation leading to decreased snowpack. Several critical knowledge gaps contributed uncertainty to our estimates. First, more studies coupling climate projections to groundwater systems are needed. Second, a generally poor understanding of mountain system processes is a source of significant uncertainty. Third, the response of focused recharge to potential changes in precipitation intensity and frequency is uncertain due to a lack of process understanding and the limited ability of climate projections to forecast changes in precipitation. Finally, feedbacks between climate, irrigation practices, and recharge result in significant uncertainties in several highly developed aquifer systems regarding how they might respond to climate change.