INFLUENCE ON DEPOSITION OF SUSPENDED SEDIMENT BY DIFFERENCES OF FLOOD PLAIN HEIGHT AND VEGETATION EXISTENCE

Abstract

 Many kinds of studies regarding lateral mixing in compound channels with vegetation have been conducted. However, the effect of the flood plain height on the suspended sediment deposition has not been clarified. In this study, 12 cases experiments have been conducted by varying (1)height of flood plain, (2)the existence of vegetation and (3)concentration of suspended sediment in order to clarify the mechanism of suspended sediment deposition. The results show that suspended sediment deposition to the flood plain is defined by horizontal vortex, concentration gradient of sediment from river channel to flood plain and section size of momentum exchange. When vegetation invades to flood plain, sediment deposition is promoted instantly with reduction of flow velocity in vegetation area.