Fresh groundwater lens evolution in artificial islands accompanied with silt uplift

Silt uplifts at the base of artificial islands have significant impacts on the development of fresh groundwater lenses and the desalination process within island aquifers, which were often overlooked in previous research. Using numerical simulations, we analyzed the effects of various silt uplift configurations on the evolution characteristics of freshwater lenses in artificial island aquifers. The results indicate that freshwater lenses in central uplift configurations reach steady state faster than those in marginal uplift configurations. In both central and marginal uplift configurations, increasing the silt uplift height substantially enhances the proportion of freshwater volume before reaching steady state. Longer silt uplifts initially increase the proportion of freshwater volume but ultimately reduce it at steady state due to spatial constraints. The silt uplift heights have minimal impact on the total salt mass removal rate in the central uplift configuration, whereas marginal uplifts with taller heights exhibit faster and higher salt removal rates until steady state. Short and tall silt uplifts expedite steady-state attainment in the central uplift configuration. For marginal silt uplifts, an increase in uplift height enhances the proportion of freshwater lens volume when the uplift length is less than 476 m. However, this proportion decreases when the uplift length exceeds 476 m. The influence of marginal uplift heights on the stabilization time is minor. Based on these findings, we could optimize the combination of short and tall silt uplifts to maximize freshwater volume and minimize the steady-state time, providing valuable insights for improving groundwater storage on artificial islands.