FORMATION OF DYNAMICALLY STABLE BEACH USING SPUR DIKE IN UKISHIMA REGION IN LAKE KASUMIGAURA

Abstract

Beach nourishment was carried out in the Ukishima region in Lake Kasumigaura to recover a sand beach. A spur dike extending in the direction of predominant waves from NW was attached to the existing groins to prevent the nourishment sand from flowing out at the downdrift end of the groin. After the beach nourishment, aerial photographs had been taken to investigate the shoreline changes and the monitoring surveys such as the bathymetric surveys and sampling of the lakebed material were carried out. It was confirmed that a dynamically stable beach was successfully formed by the construction of spur dike. Sand, the grain size of which is smaller than 0.35 mm, was transported into the zone deeper than Y.P.+0.2 m due to the sorting effect of waves.