LARGE BEACH CHANGES TRIGGERED BY CHANGE IN WAVE DIRECTION OF PREVAILING WAVES ON OGIMI COAST IN OKINAWA

Abstract

 The direction of the prevailing waves incident to a pocket beach of the Ogimi coast in Okinawa was ivestigated using satellite images. The direction of incident waves has changed counterclockwise from N33°W to N57°W by an angle of 24° since 2009, resulting in the rotation of the shoreline. Detached breakwaters have been constructed along the shoreline of the convex shape and the shoreline orientation changes by 56° at the middle of the detached breakwaters. So, eastward longshore sand transport took place at No. 3 detached breakwater, located at the location where the orientation changes, in response to the change in the direction of prevailing waves, causing large beach changes around the detached breakwaters.