USING A BREAKWATER FOR BEACH PROTECTION

Abstract

This study consists of two part: In the first, the effect of the presence of a breakwater on the profile of a beach has been studied. The tests were preceded by a study of the kind of disturbance arising behind a breakwater, which set forth the occurrence of harmonics of the incident wave. During these tests, it was possible to observe the different kinds of breaking over the structure resulting from the characteristics of the incident wave and the layout of the structure. Three typical kinds of breaking were distinguished : a horizontal jet of water, a descending jet and partial breaking; all intermediate conditions being liable to happen. In the second part, a study has been made of the layout of an immersed breakwater intended as a local beach protection. Great difficulties may arise in this solution, if it is affected by coastal drift prevailing in one direction. Indeed, the partial destruction of wave energy in a certain coastal area reduces the drift and this causes a more or less heavy deposit towards one end of the breakwater and consequently erosion, which may be very marked, near the other end.