The wave transmission over submerged breakwaters is investigated using existing formulae and wave models. The objective is to assess their performance and pinpoint research paths for their improvement. Application was made on a case study with two submerged detached breakwaters. It was found that some of the recent relations give satisfactory results of the transmission coefficient, while the predictability of the models tested depends on the wave breaking formulation assumed. In general, wave breaking and porosity of the structure are the most crucial factors that need further study for the improvement of the prediction of wave transmission over submerged breakwaters.
Coastal protection has always been a field of challenge to engineers due to the complexity of the physical processes involved. In modern times the issue becomes even more complicated, since other non-physical parameters are introduced during the conceptual design of a coastal project. Such considerations may include the environmental and in particular, the aesthetic value of the nearshore landscape. Thus, new forms of the conventional structures are being tested along with new approaches to coastal protection employing mild-type structures. In this framework it is not wonder that low-crested structures and in particular submerged breakwaters, a modified version of the traditional detached breakwater, are increasingly used in projects aiming primarily at combating coastal erosion. The protection afforded by submerged breakwaters to their lee controls the nearshore wave pattern, the sediment movements and finally the morphology of the coastal zone. A prime measure of this protection is offered by the wave transmission over such structures. The commonly used wave transmission coefficient provides the anticipated decrease of a characteristic wave height due to the presence of the submerged breakwater. As expected, the main parameter that affects the transmission coefficient is the freeboard, i.e. the distance between the sea free surface and the crest of the structure.
