Levee breach process of a river by overflow erosion

In Japan, most of population and property concentrate to floodplain, and the main facility against flood is continuous flood levee, thus, the river administers have constructed flood levees with arranging flood control dams to suppress the disaster against flood. However, due to heavy rainfalls that exceed the design or equipped facility level, inundation due to breach of flood levee have often caused serious disasters. We are aware that it is necessary to prepare evacuation system against contingency, and in this purpose it is necessary to know how the breach develops as time process. In this paper, we explain how it is important to clarify the evolution process of levee breach, and develop a numerical simulation of the breach process that can evaluate the toughness of levee and floodplain against flood.