On the mutual relation between profiles and waves of sandy beachs

There are a stable point relating the movement of sand near the wavebreaking point in the beach profile. It is described in this present paper that the change of beach profileat 17 coasts of Japan is analyzed by using Ursell number (Ur=HbLb2/hb3) in relation to waveheight (Hb), wave length (Lb) and water depth (hb) at the wave breaking point from the wave observation data, and a stablepoint (hc) of beach profile is explained by the Ursell number (Ur) andthe wave breaking point (hb).