Background
The following shows an "idealized" model of coastal groundwater interaction. In an idealized case, the groundwater flow is governed by the still (or mean) water level in the lake and the hydraulic head at some point inland from the water body, Dh. Groundwater flow is in the general direction from inland towards the lake.
This idealized model makes many assumptions about the interaction between the lake and the coastal aquifer. One big assumption is that the wave action in the lake does not have an effect on the groundwater table or groundwater flow. A more realistic model adds both run-up and setup caused by wave action in the lake.
Inflow of surface water from the wave setup and run-up along the beach can cause a local high in the groundwater table and may create a circular groundwater flow pattern. The circular groundwater pattern can have a great impact on the water quality along the beach. Contaminants that are introduced either by the surface water or the aquifer may become trapped and accumulate along the beach.
Conversely, a local high in the groundwater table caused by wave run-up and setup may have beneficial effects on coastal wetlands, which are dependent on a water table that is near the ground surface.