The Study for Sediment Disaster at the Vulnerable Area Using Debris Flow Estimating Model

Abstract

Torrential rains occurring during the unpredictable climate change cause many mountain disasters in vulnerable areas. This study is to analyze the debris flow mechanism by applying the multiplier of the vulnerable area debris flow prediction model presented by USACE to the erosion or sedimentation model. The higher the typhoon category, the higher the debris flow peak value, and the frequency of peaks of flow discharge with long durations increased. Analysis of changes in vegetation density showed that the initial peak value of the debris flow reaching the bottom was highest due to dense vegetation, and high-amplitude fluctuations appeared due to energy dissipation. In the case of heavy rainfall, the peak value of debris flow increased by more than 22%, and fluctuations of flow discharge occurred earlier at the elapsed time. In addition, debris flow fluctuations with high wave heights appeared, and the high-amplitude band width also appeared to be quite long. The analysis of present study will provide information for developing and prevention disaster reduction measures in vulnerable areas.