The social mechanism of rapid disappearance of natural sandy beach caused by lack of adjustment between protection of coastal forest and shore protection is investigated through the case study on the Niigata coast facing the Sea of Japan. This coast has been eroded for a long time because of decrease in sand supply from the Shinano River, which is the main supply source to this coast, and subsidence of the ground level due to the excess pumping-up of natural gas. Until now, most severe erosion expanded west of Shinkawa fishing harbor. Coastal forest extends along this coastline and in order to protect this coastal forest, seawall has been constructed without sufficient understanding of causes and mechanisms of shoreline recession, and this brings a monotonous extension of artificial coastline covered with seawall. In order to change this situation, the overall cooperation between the works of shore and coastal forest protections is needed as well as the comprehensive consideration of stabilization of all the Niigata coast.
