Analytical study for wave-induced submarine groundwater discharge in subtidal zone

Abstract

Both tide and wave are significant coastal driving forces of submarine groundwater discharge (SGD). The hydrodynamic process of tidal SGD is well studied while wave induced part is still challenging to quantify. In this paper, an analytical study was performed to investigate wave-induced SGD in a subtidal aquifer extending horizontally infinitely with impermeable horizontal bottom. The loading effect of seawater weight overlying the seabed was taken into account. The analytical solution was validated by two-dimensional numerical simulations with modeling domains of finite horizontal extension length. Sensitivity analyses of the analytical solution showed that the amplitude of groundwater head fluctuations generally decayed exponentially with the aquifer thickness, and the decay rate decreased with increasing loading efficiency. Loading effect can decrease the head gradients between seawater and porewater. Wave-induced SGD generally increased with the aquifer’s thickness, permeability, wavenumber, wave period, and decreased with the loading efficiency and specific storage of the aquifer. The analytical and simulated results may provide guidance for assessing the wave-induced SGD and shed light on modeling the biogeochemistry process in wave dominated porous seabed environment.