Beaches in Japan have been eroding since the 1970's as a result of the artificial land alterations. Approximately 3000 fishing ports and 1000 commercial ports have been built nationwide, as well as 2532 large dams being constructed in the upstream basins of large rivers. Due to the port and dam developments, fluvial sand supply has significantly reduced resulting in shoreline recession around the river mouths. Continuous sand supply along the coastline has also been obstructed by the port breakwaters. The formation of wave shelter zone by the port breakwaters induce longshore sand transport...