Assessing the impacts of extreme precipitation on groundwater recharge under diverse hydrogeological conditions via the theis equation

Climate change has amplified the frequency of extreme high-intensity precipitation events, altering groundwater recharge across diverse hydrogeological settings. Using observed precipitation, groundwater level (GL), hydrogeological drilling data, and the Theis equation, we quantified how precipitation affects groundwater in the Baiyangdian-Basin Plain. We found that GL declined in 80% of counties, with a milder decrease in piedmont regions. During rainy and irrigation periods, the cumulative rise and fall of GL accounted for 55.3% and 57.5% of the annual total, respectively. Short-duration intense precipitation dominates annual water gain in wet years and amplifies inter- and intra-annual GL fluctuations. When precipitation exceeds 600 mm/year (intensity >8 mm/day), both GL recovery and well flow rate decline rapidly, implying reduced groundwater recharge. In the piedmont, precipitation is strongly positively correlated with GL and well flow rate, indicating little impact of extreme precipitation on groundwater recharge. These findings prevent the overestimation of groundwater recharge from extreme precipitation.