The Impact of Climate Change on the Groundwater Recharge in the Sonoran Desert - Eline Mol

Abstract

This report researched the impact of climate change on groundwater recharge in the Sonoran Desert. The Sonoran Desert is an arid region, located in the southwestern United States and northwestern Mexico. Known for its susceptibility to water scarcity, the region has implemented policies addressing (ground)water availability to ensure future water security. Groundwater currently serves as the primary source, supporting urban, industrial and agricultural sectors.

Climate change is expected to affect the region, following the trend where wet regions become wetter and dry regions become drier. Given these concerns, this research aims to address the following research question: “How will climate change influence groundwater recharge in the Gila River basin in the Sonoran Desert over the 21st century?”.

This research has utilized the eWaterCycle platform, which currently contains six different hydrological models. For this study, the hydrological model PCR-GlobWB has been used. This model can simulate groundwater recharge. Through the application a water balance, an approximation of groundwater recharge can be simulated.

Historical groundwater recharge data were simulated using an ERA5 forcing , providing a benchmark for evaluating future climate scenarios. These future climate scenarios were simulated using a CMIP6 forcing, focusing on three scenarios: SSP1-2.6, SSP2-4.5 and SSP5-8.5. These scenarios correspond to an optimistic climate scenario, a middle road scenario and the worst-case scenario, respectively.

The findings of the research indicate that the simulated groundwater recharge values, directly derived from PCR-GlobWB, are not realistic values. In contrast, the approximated groundwater recharge values provide a more realistic magnitude. The main findings from the approximated groundwater recharge simulations suggest a decline in groundwater recharge in all scenarios. The scenario SSP1-2.6 has a decrease in groundwater of 2.9%, SSP2-4.5 has a decrease of 6.2% and SSP5-8.5 has a decrease of 5.6%.

Efforts to address the anticipated reduction in groundwater recharge have already been initiated by institutions in Arizona, California and Mexico through implementation of strict water regulations. However, additional measures are needed to further reduce the negative effects. For instance, sustainable water management and restoration of natural water flow are critical. Current policies aim at replenishment of aquifers are a promising start, and should be sustained and expanded to enhance long-term water security and environmental sustainability.