Figure 1. Location of the study site and topography of the beach transect.

Four piezometer wells (PW1−PW4) were installed along the intertidal zone of the beach to monitor groundwater table fluctuation due to tidal action. The mean sea level was assigned as the elevation datum (0.0 m). Major processes of subsurface pore water flow and salt fate are illustrated in the Figure, including the upper saline plume, the freshwater discharge tube, the classic saltwater wedge, and pore water evaporation from the beach surface. Note the exaggerated vertical scale. The map of the studied site is obtained from Jackson et al.³¹.