1998 Volume 14 Pages 405-409
A new type of shore protection, the shape of which is an overhanging inverse triangle, called the“nabla”type, is proposed to reduce crest height and wave overtopping amount. Crest heights and wave pressures when using this shore protection are investigated by experiments using a water channel. The crest heights of the nabla type are almost as low as that of the“flare”type, the shape of which is an overhanging circular arc, and about 2/3 lower than that of the conventional vertical shore protection. It is shown that the crest height mainly depends on the specific volume between the front of the shore protection and the water surface. It is thought that the nabla type is useful due to its simple shape in comparison with the flare type, although wave pressures when using the nabla type become a little larger than that of the flare type as the depth of water decreases and transfers to the wave breaking region.