The Pattern of Fresh-Water Flow in a Coastal Aquifer

Abstract--Formulas are developed for the flow pattern followed by the seaward-moving fresh ground water as it nears a beach. It is found that, under steady flow conditions, a sharply defined interface is formed between the fresh and salt water. Along the interface the pressure of the static salt water, owing to its greater density, is counterbalanced by the pressures which drive the fresh water seaward. The fresh water escapes through a gap between this interface and the shore line. An increase in the flow of fresh water widens the gap. Tidal action causes a diffusion of salt water across the interface. This salt is carried back to sea with the fresh-water flow. Introduction--Where permeable beds under-lie a land area near the sea and extend some distance seaward from the shore line, the in-filtration from rainfall causes a continuous flow of fresh water toward the sea. It has been foun