BEACH EROSION NORTH OF NO. 4 BREAKWATER ON SHIMIZU COAST DUE TO DISRUPTION IN BALANCE OF LONGSHORE TRANSPORT

Abstract

 In the area between L-shape groin and No. 4 breakwater on the Shimizu coast, measures against beach erosion which reduces minus impact to the scenic beauty of the coast have been taken. To this purpose, detailed investigations have been carried out on the beach changes in the area between L-shape groin and No. 4 breakwater. On the other hand, beach has been eroded over time despite the beach nourishment downcoast of No. 4 breakwater located at the north end of the coast, which is in contrast with the significant shoreline advance upcoast due to the beach nourishment. Thus, the shoreline recession in this area due to decrease in longshore sand transport approaches to the level not to be acceptable. In this study, while comparing the beach changes in the areas upcoast and downcoast of No. 4 breakwater, erosion downcoast of No. 4 detached breakwater was investigated in detail and future measures against erosion were described. It was concluded that appropriate measure is the continuation of beach nourishment downcoast of No. 4 breakwater.