Evaluation of the Risk Distribution of the Debris Flow Occurred Using Numerical Simulation Subjected to Rockfall

The Hiroshima torrential rain and sediment disaster that occurred from 19 to 20 August 2014, brought a huge disaster to the private house on the alluvial cone. It was conducted a debris flow disaster focusing on this alluvial cone. In this survey, it was found that in the hornfels distribution area, there are many stones and gravels and the matrix content is small, so the alluvial cone becomes steep and the debris flow does not reach relatively far. In other words, from the viewpoint of disaster prevention and disaster prevention, it is important to think about land use while keeping in mind that the slope of the alluvial cone in the range where the debris flow in the upper part of the alluvial azimuth falls directly differs from geology. Although prediction analysis has been tried from such a disaster case, it has not yet been reflected in the design. It is desirable to predict highly accurate predictive analysis, but first of all, it was calculated by a simple calculation method as much as possible.