Flow and Inundation Characteristics of Debris Flow Occurred in Hiroshima City on August 2014

Debris flows were occurred in Yagi 3 Chome, Asaminami, Hiroshima on 20 August 2014. The geology around Asaminami area is granite which has many joints and is easy to be weathered. Hence, the permeability of the seepage is high and fine sediment is easy to be produced. In this study, the horizontal two dimensional debris flow model considering the both the laminar and the turbulence flows is developed. Subsequently, the model is applied to the debris flow occurred in Yagi 3 Chome, Asaminami, Hiroshima and discussed the applicability of the model. The differences of the horizontal inundation areas in the residential area between the simulated results and the field data are discussed and it was found that the horizontal distribution of the sediment deposition of the coarse material is reproduced well. When the houses are considered in the analysis, sediment deposited in the upstream region of the houses and the inundation area is reduced.Debris flows were occurred in Yagi 3 Chome, Asaminami, Hiroshima on 20 August 2014. The geology around Asaminami area is granite which has many joints and is easy to be weathered. Hence, the permeability of the seepage is high and fine sediment is easy to be produced. In this study, the horizontal two dimensional debris flow model considering the both the laminar and the turbulence flows is developed. Subsequently, the model is applied to the debris flow occurred in Yagi 3 Chome, Asaminami, Hiroshima and discussed the applicability of the model. The differences of the horizontal inundation areas in the residential area between the simulated results and the field data are discussed and it was found that the horizontal distribution of the sediment deposition of the coarse material is reproduced well. When the houses are considered in the analysis, sediment deposited in the upstream region of the houses and the inundation area is reduced