Author(s): Kenji Kawaike; Kazuya Inoue; Keiichi Toda; Tsutomu Nakai
Linked Author(s): Keiichi Toda, Kazuya Inoue, Kenji Kawaike
Keywords: Hillside cities; Sediment yield; Inundation flow analysis
Abstract: In this paper, an inundation flow model in hillside cities is developed considering the effects of sediment. In this model, the studied area is divided into upstream area (mountainous area) and downstream area (urban area). In the mountainous area, which comprises tributaries, slopes (without sediment) and main stream (with sediment on the bed), the runoff discharge and sediment concentration hydrograph at the downstream end of main stream are calculated using the kinematic wave model and the one-dimensional dynamic wave model. In the urban area, applying these hydrographs as the boundary conditions at the upstream end, the two-dimensional inundation flow analysis is conducted using unstructured meshes. The meshes for computation are divided into three types of categories; river, street and flood plain. In order to consider the effects of streets and buildings in urban area, the occupying ratio and the invasion ratio are introduced, and roughness coefficient is changed according to the mesh category. The above model is applied to Ikuta River basin in Kobe city, Japan. The obtained results show that the scale of inundation is much larger than that of the case without sediment. Therefore, it is very significant to consider the effects of sediment in the inundation flow analysis in hillside cities.
Year: 2001