LAUSR

Coastline changes caused by anthropogenic and natural influences inevitably alter coastal wetland groundwater levels. In this study, we apply Visual MODFLOW (VMOD) to assess the influence of different zonal coastline types (e.g., accretion, erosion, and stable zones) on groundwater levels of a coastal wetland in the Yellow River Delta (YRD), China. We also discuss the conceptual framework of groundwater level variation in accretion, erosion, and stable zones. Results show that: (i) The groundwater flow field varied with coastline changes in this seaside region, while a similar variation pattern was also found in both the upper southwestern region and the riverside of the Yellow River where groundwater levels are high; (ii) groundwater levels increased with the expansion in land area caused by silting, while groundwater levels exhibited a slightly decreasing trend in the erosion zone; and (iii) coastal wetland groundwater levels exhibited a progressively and significantly decreasing trend in zones protected by a dam. We found that the mechanisms that drive groundwater levels clearly responded to coastline alteration, and such findings could help in our understanding of how coastlines influence groundwater in freshwater wetlands and aid in maintaining the integrity of coastal wetlands.