天竜川扇状地と遠州灘海岸の形成

Abstract

Recently, due to a decrease in sediment input from the Tenryu River flowinginto Enshu-nada coast facing the Pacific Ocean, beach erosion has advanced remarka-blly along the river mouth coast. The beach erosion can be considered as a reduc-tion of the deltatic alluvial fan of the Tenryu River.To consider the reduction process, therefore, formation of the alluvial fan isstudied by use of topographical and archaeological knowledge of the long-term for-mation processes of the coast. In the reduction process a remarkable influence ofriver discharge and rising sea level since the geological age has taken place on theformation and reduction of the alluvial fan.