Groundwater provides drinking water for people, supports agriculture, and sustains healthy ecosystems, but has been depleted in some regions due to overuse. Groundwater is replenished through the process of groundwater recharge. After precipitation infiltrates into the soil, a portion is returned to the atmosphere through evapotranspiration, but some may percolate downward until it reaches the water table and recharges the aquifer. The process of groundwater recharge varies substantially in space and through time due to soil type, weather conditions, and vegetation. Case studies will be used to illustrate how groundwater recharge regimes are altered by changes in climate and shifts in land use. Groundwater level responses to recharge events were used to quantify groundwater recharge rate differences at locations with different land cover. Numerical modeling was used to diagnose the causes of changing recharge rates and predict the consequences of these changes across a range of environmental settings. A process based understanding of the factors that drive changes in groundwater regimes is critical to sustainable management of groundwater resources under environmental change and avoiding or minimizing unintended consequences of human activities.