大戸川における微細砂の流送過程について

Abstract

In the floods of the River Daido, the wash load of the finner sand less than 0.2 mm in diametertakes a great part of the suspended sediment load. In order to elucidate the transport processof the wash load in the basin, we set out the observation of the changes with time of suspendedsediment concentration and water discharge at the downstream stations and the calculation ofsediment yield and transport in connection with run-off process of rainfall on the basis of hydro-logical and hydraulic approaches.The results of the calculation show that the changes of sediment concentration of wash loadare approximately in accordance with that of the water discharge at the any stations, but the sed-iment concentrations for a given discharge during a rise and a recession of a flood are differenteach other in some regions with mountain slopes of different geometrical factors. The observationpartly supports these results calculated, however, the further sutdies on the basis of the comprehen-sive observation will be needed.