Essential Aspects of Beach Erosion - Lessons from Devastation of Ichinomiya Coast, Japan

The fundamental issues of the beach erosion including the difficulty in social and comprehensive adjustments of the beach erosion were discussed through a case study, taking the Ichinomiya coast on south Kujukuri Beach as an example. On this coast, sand supply from the sea cliffs markedly decreased as a result of the preventive measures against cliff erosion on upcoast, resulting in the downcoast erosion. Artificial headlands have been constructed since the 1990 as a measure against shoreline recession, but this caused further downcoast expansion of the beach erosion. Finally, it became difficult to escape from a vicious cycle of seawall construction - downcoast erosion - seawall construction - downcoast erosion, permitting further expansion of the erosion area. Such difficulties were analyzed.