Analytical Solution for Tide-Influenced Groundwater Variation along Sloping Complex Coastal Aquifer in Presence of Rainfall Infiltration

Abstract

Coastal regions have the most challenging aquifer systems because of their geometry and the flow behavior of groundwater with tidal oscillations. Studies have focused on tide-induced groundwater fluctuations in horizontal aquifers whose base is extending under the sea by ignoring the fact that coastal beaches are sloping in nature. In this study, an unconfined coastal aquifer with an extending, sloping, impermeable base under the sea in the presence of tidal waves and exponential rainfall infiltration was modeled. An analytical solution of the given hydrodynamic model with boundary conditions was developed, which represents the similarity of water table heights at two points in the given spatial domain. Nonlinear Boussinesq equations were linearized to develop the model. The closed form of the analytical solution was obtained using various transform methods. The efficiency of the linearization method was determined using the alternating direction implicit scheme. Relative percentage difference was used to analyze the error statistics between analytical and numerical results. Further, temporal and spatial distributions of the water table were presented for different bed slopes, tidal patterns, and rainfall infiltrations. The derived solution provided the responses of the coastal aquifer with a sloping base extending under the sea to tidal oscillations in the presence of rainfall infiltration. The developed model is useful for field and experimental applications of coastal aquifer systems such as seawater intrusion studies and water clogging on the coastal interface owing to the deposition of silt, clay, and pollutant particles.