Effect of evaporation on soil salinization caused by ocean surge inundation

Abstract Ocean surge inundation occurs frequently in low-lying coastal areas worldwide. While studies have been conducted to examine aquifer salinization and recovery caused by ocean surge inundation, evaporation is predominantly overlooked. Based on numerical simulations considering variably saturated, density-dependent pore-water flow and salt transport, this study examines the combined effects of evaporation and ocean surge inundation on soil salinization in coastal unconfined aquifers. The results show that evaporation enhances soil salinization caused by ocean surge inundation. Due to evaporation-induced water uptake, the downward movement of salt is weakened and the salt from the ocean surge inundation is significantly trapped in the unsaturated zone. The pore-water salinity in the shallow soil layer is increased by soil evaporation, particularly in the low-elevation area with longer seawater inundation. The sensitive analysis shows that the evaporation-enhanced soil salinization is more remarkable for silt-loam and clay-loam aquifers rather than sandy-loam aquifers. A higher mean sea level favors salt trapping in the shallow soil layer of aquifers. These results demonstrate the importance of evaporation on soil salinization caused by ocean surge inundation, and that could be considered in future studies.