DEPOSITIONAL EFFECTS OF OFFSHORE BREAKWATER DUE TO ONSHORE-OFFSHORE SEDIMENT MOVEMENT

摘要

Physical parameters controlling the development of tombolo behind offshore breakwaters are clarified on the basis of the results obtained by laboratory tests. Especially, the depositional effects are evaluated by taking a permeable type structure into account. They are wave characteristics, sediment size, the water depth where the structures are to be placed and its dimension. The amount of sand deposition behind the structures is presented by non-dimensional parameters such as the relative distances from the initial shoreline to the structure and to the breaking point of waves, the ratio of the gap width to the wave length in deep water and the ratio of the length of the offshore breakwater to the wave length in deep water.