2024 Volume 80 Issue 16 Article ID: 23-16092
In Azuma River basin, the bare slopes formed by the 2018 Hokkaido eastern Iburi earthquake may impact the sediment dynamics of the river channel in the long term due to the sediment supply from the surface layer during rainfall. However, the surface layer of the bare slope in this watershed area is a complex mixture of clay and sand, which makes the prediction by the existing method difficult. In order to simulate the sediment dynamics under the characteristics, this study conducted the following four items; erosion experiment on clay-sand mixture surface employing rainfall supplier, two-dimensional riverbed deformation simulation on the experiment, developing the empirical sediment supply equation based on the analysis of the simulation results, and conducting a long-term sediment runoff simulation for the entire watershed by introducing the sediment supply equation. The long-term simulation successfully reproduces the suspended sediment observation in the downstream area. Additionally, the proposed simulation indicated that early countermeasures on the bare slopes effectively reduce sediment discharge on the multi-year scale.
