CONSTRUCTION OF OFFSHORE FISHING PORT FOR PREVENTION OF COASTAL EROSION

Abstract

When constructing a small fishing port along sandy beach, the most important considerations are how to prevent sand deposition at the port entrance and beach erosion along the down-drift side of the port. To solve these problems, an offshore fishing port connected to the shore by a bridge was planned at Kunnui, Hokkaido Prefecture. The port was designed to allow littoral drift to pass between the port and the shore. The appropriate shape and offshore distance of the port to restrict the development of tombolo was determined by hydraulic model tests and numerical simulations of wave-induced current near the port. Bottom sounding was carried out in parallel with the construction work. As a result, development of tombolo was restricted to some extent and no serious beach erosion occurred. This port seems to have generated unexpected strong cell-like circular currents on both sides, and sand deposits deposited by these currents. There are, however, no problems at present concerning the shape, offshore distance and location of the port entrance.