Author(s): Norio Tanaka; Shintaro Hisazumi; Yoshiya Igarashi

Linked Author(s): Norio Tanaka, Yoshiya Igarashi

Keywords: Compound channel deposition surface eddy suspended load middle floodplain

Abstract: River channel and floodplain excavation including tree removal are being extensively conducted for improving the flood flow capacity. For reducing the re-sedimentation, the effectiveness of the inclination of middle floodplain was demonstrated, however vegetation type and arrangement could greatly affect the sedimentation amount because of the suspended load transfer from low channel and trapping by grasses on middle floodplain. This study focuses on two heights of vegetation standing in line at the interface of low channel and floodplain, submergent grasses and emergent vegetation, under different surface eddy structures due to the difference of water depths. Flume experiments were conducted on a river channel model consisting of a low channel, a sloping floodplain (middle channel) with vegetation model, and a high-flat floodplain was set in a flume. The deposition amount of suspended load on the sloping floodplain was measured when the sand was supplied from the upstream side of the low channel. The experimental results showed that vegetation height can greatly affect the deposition amount especially when emergent vegetation exists. The sedimentation amount increased or decreased with increasing water depth in emergent or submergent vegetation cases. Vegetation greatly affects the surface eddy structures and sediment flux from low channel to middle floodplain.

DOI:

Year: 2025