ABSTRACT
Groundwater dynamics within a sandy beach influence erosion control, saltwater intrusion, chemical transformation and biological activities. In particular, accurate prediction of dynamic groundwater hydraulics in coastal zones is required to improve coastal management. Most studies of coastal aquifers are based on the Boussinesq equation together with the Dupuit assumption. To simplify the problem, most previous investigations for water table fluctuations in coastal aquifers have considered for the case of a vertical beach instead of the more realistic case of a sloping beach. In this chapter, we outline the shallow water expansion for free surface flow in porous media and further applied to the field of tidal dynamics in coastal aquifers. The concept of moving boundary is employed to overcome previous models for sloping beaches. A complete analytical solution is derived through two perturbation parameters (shallow water parameter and amplitude parameter. With similar framework, a numerical perturbation approximation (up to 24th order) for the tidal dynamics in coast aquifer is presented.
