Publication
Beach recovery describes the processes by which there is a natural restoration of beach material and coastal morphology following storm events, and these processes are common across the globe. However, the effects of beach recovery on salinity distribution and solute transport in unconfined coastal aquifers are poorly understood. This study examined the changes in salinity distribution in tidally influenced aquifers in response to beach recovery, based on numerical modeling. The extent and location of the upper saline plume and saltwater wedge were found to vary with the beach recovery. The variations in salinity distribution directly changed the particle travel times in the aquifers. Compared with the erosion profile after the storm (storm profile), an increase of up to 743% of the particle travel time in the intertidal zone was observed when the beach recovered to a berm (silting) profile. The berm profile increased the residence time and peak concentration of the land-sourced solute plume in the beach aquifer compared with the storm profile. The berm profile also enhanced the aquifer-ocean mass exchange, resulting in increased intertidal saltwater infiltration and submarine groundwater discharge. On the other hand, the storm profile can generate much higher solute efflux than the berm profile. The storm profile is more favorable in diluting the land-sourced conservative solute and shortening its residence time in an aquifer.