BEACH AND DUKE EROSION TESTS

Abstract

In the Netherlands a large part of the country lying below sea level is protected by sand dunes. The erosion of sand dunes during storms at the North Sea, by which the strong wave action is attended with a high sea level, is therefore of extreme importance in the Netherlands. It is almost impossible to do adequate measurements along the coast during storms. Accordingly the Delft Hydraulics Laboratory was requested by the Public Works Department of the Dutch government to investigate in a model a number of matters related to both the maintenance of existing dunes and the design of artificial sand dunes as sea defence works. The investigations reported in this paper are concerned with the following problems a) the influence of the height of sand dunes upon the amount of coastal recession during storm conditions. b) the influence of the wave characteristics upon the amount of coastal recession. c) the differences in coastal recession and profiles obtained with regular waves and those obtained with wind waves. The reproduction on scale of the phenomena m the surf zone is a difficult matter. Many investigators have come to the conclusion that there are several scale effects. Till now our knowledge is not sufficient to determine the magnitude of the scale effects. Owing to this the described tests can give only qualitative information.