Influence of time-space variability of rainfall infiltration recharge on fresh groundwater lens.

This article focuses on the development and application of a two-dimensional numerical model to investigate the effects of spatiotemporal variability in rainfall infiltration recharge and artificial recharge on the freshwater groundwater lens (FGL) dynamics of Yongxing Island, a coral atoll in the South China Sea. The study finds that land reclamation increases the thickness and storage capacity of the FGL by creating new aquifers, while using average annual rainfall instead of monthly data tends to overestimate freshwater storage due to the uneven distribution of tropical rainfall. Additionally, artificial recharge concentrated in the island’s central area enhances groundwater levels and freshwater volume, with more concentrated recharge areas improving recharge efficiency but altering the lens shape. These results provide theoretical insights for sustainable groundwater management on islands, though the model’s simplifications highlight the need for future three-dimensional, heterogeneous modeling incorporating tidal effects.