Prediction of landslide-induced debris flow hydrograph: The Atsumari debris flow disaster in Japan

Landslides sometimes occur on mountain slopes by heavy rains. Some of them change into debris flows and then move into mountain rivers. The debris flows erode the river bed and increase their discharge. Prediction of debris flow discharge becomes important for the simulation of flooding debris flows along the river. The purpose of the present study is to develop a prediction model of the landslide-induced debris flow hydrograph. This study is composed of three steps. First, we assume a transformation model of landslide into debris flow. Second, we calculate the development process of debris flow in the middle reach and determine the debris flow discharge. Finally, we simulate the flooding process of debris flow in the downstream reach.