台風7617,7916,7920号による高知海岸の災害について

Abstract

Beach erosion is a matter of great concern in Kochi coast where the shoreline has receed-ed more than 5Om during the past thirty years. Especially, near the river mouth, thebeach erosion is caused by remarkable decrease of sediment supply from rivers into thecoast and is accelerated after the construction of dams.This paper presents the results of investingation on the disasters of seawalls occurred byTyphoons 7617, 7916 and 7920 at Kochi coast. It is concluded that the chief cause of break-down of sea walls is beach erosion. From the recent situation of beach erosion, it is pointedout that such coastal disasters will so often occurr in Japanese coasts and that necessarycountermeasures have to be carried out from the view point of long-term shore protection.