Rainfall infiltration-derived submarine groundwater discharge from coastal multi-layered aquifer system

The quantity of submarine groundwater discharge (SGD) from a coastal multi-layered aquifer system in response to constant rainfall infiltration is investigated. The system comprises an unconfined aquifer, a confined aquifer and an aquitard between them and terminates at the coastline. An approximate analytical solution is derived based on the following assumptions: (1) flow is horizontal in the aquifers and vertical in the aquitard, and (2) flow in the unconfined aquifer is described by nonlinear Boussinesq equation. The SGD from the confined aquifer increases with the inland rainfall infiltration recharge and the specific leakage of aquitard. The maximum SGD ranges from 1.87 m³/d to 10.37 m³/d per meter of shoreline when rainfall infiltration ranges from 18.2 mm/yr to 182 mm/yr and the specific leakage of aquitard varies from 10^-9 1/d to 10^-1 1/d.