Climate change impacts go beyond the surface: Groundwater recharge rates and aquifer resources across the Contiguous United States

Groundwater is a primary source of potable water for millions and a major source for crop irrigation in the United States. Thus, it is vital to understand current and future rates of recharge to predict and manage groundwater availability. In this study, current groundwater recharge rates across the Contiguous US at 800m resolution are estimated by following methods presented by Reitz et al. (2017), and the reproducibility of the methods are assessed. A water budget approach is implemented where quick flow runoff and evapotranspiration rates are subtracted from precipitation rates. Precipitation was found to be the most reproducible water budget component, whereas evapotranspiration and quick flow runoff were found to be more sensitive aspects of the model. Final recharge estimates, dependent on the three water budget components, reflect inaccuracies produced in estimating precipitation, quick flow runoff, and evapotranspiration. Patterns in recharge rates are examined alongside the geospatial distribution of precipitation in the context of large-scale atmospheric circulation systems. In addition, changes to precipitation patterns that are expected to occur over the 21st century such as increasing precipitation in the Midwest and decreasing precipitation in the Southwest, are presented as a way of estimating changes to future groundwater recharge rates. Agriculture in the US relies heavily on groundwater resources, thus increased precipitation in the Midwest and decreased precipitation in the Southwest are expected the drastically alter US food production