Beach erosion control in front of sea cliff

摘要

The planting zone of forest reserve is frequently broken down by beach erosion. Protections of beach erosions are planned by the embankment, the revetment, the groin, the jetty, the detached breakwater or the artificial beach nourishment. The key of success on beach erosion control is to dissipate the incident wave energy and stop the sediment yield. The wave dissipating concrete block is convenient for a beach erosion control because of being changed and reinforced easily. And also, it is a good point of wave dissipating concrete block that the executing period is short and the ground is not destroyed Model tests were carried out on a movable bed in a wave tank of length 30m, width 0.7m and depth 1.2m for the purpose of investigating the arrangement and the structure of wave dissipating concrete blocks on beach in front of sea cliff. And, also, a field observation was carried out at the Kumbetsu Coast of Hokkaido in Japan where the result of models tests was applied. Results of model tests and a field observation are as follows: (1) The accretion appeared between the sea cliff and the concrete block in case of setting concrete blocks at a distance, 0.02 times of wavelength, from the sea cliff. (2) A remarkable achievement was obtained at the Kumbetsu Coast of Hokkaido in Japan by applying the result of model tests.