Author(s): Terumichi Hagiwara; Shunsuke Aita; Kazuya Watanabe; So Kazama

Linked Author(s): Terumichi Hagiwara

Keywords: Foot protection; Suspended sediment; Numerical simulation

Abstract: Protection for the foot of river banks is generally set for the purpose of countermeasure of erosion to river bank. Suspended sediment often deposits around the foot protections over time. The vegetation grown in the sediment area provides the ecological habitat. And the vegetation has possibility to increase the resistance of foot protection to the running water. It is possible to predict future topographical changes and the arrangement effect of the foot protections by simulating the sedimentation transport model around the foot protections. In this study, numerical analysis was performed about suspended sand deposition around the foot protection “Filter Unit (FU)” in hydraulic experiments and in actual river observations. The flow was calculated by two-dimensional model, and the riverbed change was obtained from the calculation considered bed load and suspended sand. The calculation result showed a good match about the tendency of suspended sediment deposition in both the hydraulic experiment and the actual river. In the hydraulic experiment case, the flow velocity decreased in the FU area due to the resistance of the FU. Although suspended sand was deposited in low velocity area, no deposition was observed in excessively low velocity area, because the suspended sand did not flow in. It was found that a certain flow velocity was required for the suspended sand deposition. In the actual river case, the suspended sand did not deposit during high discharge period because of high velocity even in the FU area. During the low discharge period after the flood peak, the flow velocity decreased in the FU area, resulting in the deposition of suspended sand.

DOI: https://doi.org/10.3850/IAHR-39WC252171192022221

Year: 2022