Methods to create hazard maps for flood disasters with sediment and driftwood

Abstract

As flood disasters with sediment and driftwood are becoming severe, it is required to evaluate the risk of such disasters. The present study proposes methods to create hazard maps for such type of flood disasters using a watershed model and a 2-D flood flow model, and applied the methods to the Akatani river flood disaster in 2017 to discuss their applicability and challenges. The upstream boundary conditions of 2-D flood flow model are specified for the hydrographs of flow discharge, sediment discharge and driftwood discharge by using the results obtained from their basin model. As a result of the Akatani river simulation with the proposed methods, we found that the computational results reproduce the inundation area and elevation change, and the proposed methods are effective in creating flood hazard maps with sediment and driftwood.