SHORELINE CHANGES OF A POCKET BEACH TRIGGERED BY CONSTRUCTION OF PORT BREAKWATERS AND FUTURE MEASURES - THE EXAMPLE OF SHIRATSURU BEACH

摘要

In Japan there are many pocket beaches of a variety of scales, and many fishing villages with a small port locate there. Historically these fishing ports have been located on the lee side of the headland, because of the wave-sheltering effect of the headland itself. In recent years, in order to modernize the fishing port, the facilities of the fishing port have been expanded, with the frequent construction of the new port in the outer region of the old fishing port. Although the enlargement of the fishing port was attained as a plan by this activity, many cases have been reported, in which the wave-sheltering effect affected the overall wave field on the pocket beach by protrusion of the breakwater from the lee side of the headland and induced severe beach erosion in the surrounding area. This study aims at investigating this problem, taking the Shiratsuru beach in Kumamoto Prefecture in Kushu in Japan as the example, and future measures are considered.