Representing Equilibrium Beach Profiles with an Exponential Expression

Abstract

Representative beach profiles from the U.S. east coast and the Gulf of Mexico were fit to two mathematical expressions below the water line: (1) the well-known h = Ax^2/3 shape, and (2) the exponential shape h = B(1 – e^-kx). For a majority of the profiles, the exponential shape more closely approximated the measured data. Generally, the exponential shape may be an improved representation of equilibrium beach profiles particularly when grain size varies in the offshore direction. Its leading coefficient may yield insight to the selection of a functional depth of closure and its exponential coefficient may be related to sediment size and/or its offshore gradation.