Abstract
Numerical simulations are performed to examine the groundwater-flow fields in sandy-beaches. The model is based on Richards equation for saturated-unsaturated flow and advection-dispersion equation for salinity, incorporating tidal fluctuations into the seaward boundary conditions. The advantage of the present model is that it can accurately simulate unsteady behavior of groundwater in unconfined coastal aquifers considering the effects of water-level variations, density distributions and dynamics in the unsaturated zone. Computational results show that circulations are formed in the aquifer near the shoreline owing to the tidal oscillations, and accordingly saline seawater exists in this part. In addition, the structure of the circulation is greatly affected by amplitude of tidal fluctuations, density distribution, land-derived freshwater discharge, beach slope, and aquifer thickness.
