Author(s): Nao Nakashima; Tatsuhiko Uchida; Yoshihisa Kawahara
Linked Author(s): Tatsuhiko Uchida, Yoshihisa Kawahara
Keywords: Component; Sediment transport; Porosity; Sediment mixture; Packing model
Abstract: Recently, sediment floods have frequently occurred in Japan due to heavy rains and have caused extensive damage. One reason for these floods is that the amount of sediment supplied from the sabo dams exceeds the amount of sediment that can be transported by water flow in the downstream river. Debris flow sediments captured by sabo dams have a wide particle size distribution. Therefore, it is necessary to evaluate the amount of sediment transported from the sabo dams as a function of grain size distribution. However, the conventional sediment transport model does not take into account the change in porosity induced by the change in particle size distribution. The objective of this study is to develop a sediment transport model to calculate the temporal variations in sediment height and size distribution simulating sediment porosity. In this study, the porosity of sediment was simulated by the Eulerian deposition model (Hayashi et al., 2019), which did not include any artificial thicknesses such as the active layer. This model was extended to an erosion model and coupled with computational fluid dynamic models and sediment transport models. This numerical analysis method was applied to an experiment using riverbed material, which was conducted to clarify the change in sediment volume and porosity. The present method captured the sorting process of the riverbed and reproduced variations in volume and sediment size distribution simulating the porosity of the sediment.
Year: 2020