Beach Evolution in the Vicinity of a Submerged Bar

Abstract

Two closely related processes which determine the evolution of the sea bottom topography with time are studied: the refraction of waves and the littoral sediment transport produced as a result of those waves. The initial sea bottom is an isolated shore-normal bar which smoothly spreads alongshore and offshore. Refraction is computed with standard numerical procedures and the littoral transport obtained through CERC's formula. The gradient of this littoral drift, together with the equation of sediment continuity, give the amount of sediment eroded or deposited. The subsequent change of bathymetry is forecasted. These cycles of refraction-littoral transport-change of bathymetry are repeated, and the evolution of the bar is followed in the course of time. An attempt is made to study the problem in its essentials, reducing the number of variables to a minimum and separately analysing each of them. Straight and non-straight coastlines are treated because of their opposite influence upon the beach evolution process.