Berm breakwater structures: Roundhead stability of berm breakwaters / Reshaping breakwater - Longshore transport and recession of the berm

For berm breakwaters as compared with traditional rubble mound breakwaters, special measures have to be taken for the breakwater roundhead. If stone displacements occur on a roundhead, the stones will be moved in the wave direction and will loose most of their stabilising effect. A point of special concern is whether, and under which conditions, a berm breakwater roundhead will develop in a way that in the long-term will lead to structural failure. The major part of the research on berm breakwaters has concentrated on the reshaping of the seaward side cif the trunk under perpendicular wave attack. Only a little research has been made to study the stability of berm breakwater roundheads (eg Burcharth and Frigaard, Jensen and Serensen, and Van der Meer and Veldman). Comprehensive three-dimensional model tests have been carried out to study the reshaping of the roundhead as function of the wave conditions (wave height and wave period) and the angle of wave incidence. The reshaping process and the movements of stones on the berm have been analysed based on both profile measurements and observations.