The relationships between wind records, energy of longshore drift, and energy balance off the coast of a restricted body of water, as applied to the Baltic

Abstract

An attempt is made to derive from wind records the intensity of the longshore drift. Based upon the fundamentals of modern wave forecasting and knowledge of the relative efficiency of different angles of wave approach, the yearly course of drift energy is calculated for four points on the coast of Schleswig-Holstein (western coast of the Baltic). By subdividing the wind records into four classes of strength, four patterns of drift energy related to distinct zones of water depth are presented. A comparison of the drift energy calculated for three neighbouring points permits a derivation of energy balance for the central point. The knowledge of the patterns of both drift energy and energy balance allows insight into the mechanism of the longshore drift. Until the present time, however, the quantitative relationships between drift energy and true volume of material transported thereby are still unknown. To avoid disturbing influences of distant wave patterns the energy cannot be calculated in the manner applied here, the method presented is valid only for a restricted area, i.e., the magnitude of the more or less uniform wind field should be similar to that of the corresponding marine area.