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Impacts of Climate Change on Groundwater Recharge in Wyoming Big Sagebrush Ecosystems are Contingent on Elevation

Lindquist, Lukas W., Palmquist, Kyle A., Jordan, Samuel E., Lauenroth, William K.
Western North American naturalist 2019 v.79 no.1 pp. 37-48
Artemisia tridentata subsp. wyomingensis, altitude, aquifers, arid lands, atmospheric precipitation, climate change, climatic factors, drought, ecosystems, evaporative demand, groundwater, groundwater recharge, humans, livelihood, meteorological data, simulation models, snowpack, soil water, soil water balance, temperature, Wyoming
Water is the most limiting and important natural resource in drylands, where low precipitation, high evaporative demand, and drought events are common. Groundwater is the critical resource for human livelihoods to persist through the intra-annual dry periods in dryland ecosystems. Overexploitation of groundwater resources and the externalities associated with depleted aquifers make understanding the ecohydrology of drylands an essential issue. We focus on the water balance and climatic drivers of big sagebrush ecosystems, an important dryland ecosystem type in Wyoming that covers a large spatial extent. The goal of this project was to understand how groundwater recharge (GWR) may change in magnitude and seasonality across multiple sites in Wyoming in the future. We used a combination of fieldwork and simulation modeling to explore key climatic and ecohydrological drivers of GWR. We simulated soil water balance using SOILWAT2, a process-based ecosystem-scale soil water model, and future climate data to estimate change in GWR through 2100. We found that mean annual temperature and precipitation explained 65% of the variation in future change in GWR. High-elevation (>2200 m) wet sites had larger increases in GWR in the future compared to low-elevation dry sites. The among-site variability in GWR was also higher for sites >2200 m, which indicates that mean annual precipitation and perhaps snowpack are important explanatory variables for GWR. Our research suggests that GWR for high-elevation big sagebrush sites may increase in magnitude from current values and may occur earlier in the year, with important implications for the timing and availability of water resources.