扇状地部における河川の自然環境保全・復元目標の指標化に関する研究

多摩川永田地区を例に

抄録

The environmental change of braided river in the decades may be stabilization of channels. It has been caused by river works, dredge of river bed materials and construction of dam. It has brought us safety land use from flood, but it has been diminishing the natural feature of braided rivers, such as reduction of disturbance and dynamism. In this paper we proposed the indices for river restoration in braided river, such as Gravel-bar and Frequent area. Gravel-bar indicates dynamism and shows the percentage of gravel bar area without covered vegetation in river area. Frequent area means the lateral continuum (the aquatic area-the terrestrial area) and habitat diversity of the active flood plain, it shows the percentage flooding area of the river area. And we showed environmental change using these indices at Nagata area on the upper Tama river.