洪水氾濫による堤内地の侵食と堆積-三隅川の1983年水害の場合-

Abstract

Sediment deposition and erosion on flood plain due to overland flood flow bring serious hazardson agricultural and residential areas of river side, especially, in mountaineous rivers. This paperpresents an investigation on fluvial processes of flood plain during a serious flash flood of July1983 in the Misumi River (Shimane prefecture), based on the results of detailed field survey andsediment sampling and of a mathematical simulation on the overland flood flow.The fluvial process of flood plain in Kamikochi and Shimokochi districts was simply classi-fied into erosion areas and deposition areas with gravel and sand, which result from bed loadand suspended load transport, respectively. The deposition area due to wash load was alsofound in flood plain of Shimokochi.The calculated results of overland flood flow were fairly in accordance with the highest floodwater mark observed and the main stream direction estimated from flood plain deformation.The calculated distribution of deposition and erosion areas due to bed load also supported theobserved ones.