Determination of precipitation infiltration recharge coefficient based on multi-factor integration in the Huaibei Plain Region of Anhui Province, China

The precipitation infiltration recharge coefficient is a critical parameter in calculating precipitation infiltration recharge, exerting a significant impact on groundwater resource assessment. This study focused on the Huaibei Plain region of Anhui Province, China. Utilising experimental data obtained from Wudaogou Hydrology and Water Resources Experimental Station in Anhui Province, combined with regional land-use types, the research dynamically determined the precipitation infiltration recharge coefficient in both temporal and spatial dimensions by comprehensively considering three critical factors: mean annual precipitation, vadose zone lithology, and groundwater table depth. The precipitation infiltration recharge coefficient in the study area from 2020 to 2022 ranged from 0.11 to 0.22, exhibiting significant spatiotemporal variability. Based on the determined dynamic coefficient, the precipitation infiltration recharge for the representative year 2022 was calculated as 5.126 billion cubic metres, which is 245 million cubic metres lower than the officially published value, with an error of −4.56% which mainly stems from differences in the selected precipitation infiltration recharge coefficient and the precision of the calculation scale. Additionally, a multiple linear regression model was applied to analyse the influence of each factor on the coefficient, revealing a significant linear relationship between vadose zone lithology, precipitation, and the coefficient, while the influence of groundwater table depth was nonlinear. The findings of this study are expected to advance the refined calculation of regional groundwater resources and provide a reference for regional groundwater resource assessment.