Study on the Prediction of Debris Flow Risk Using LS-RAPID

Abstract

In this study, the LS-RAPID program was applied to evaluate the debris flow deposition area using the field surveyed topographical data in the areas of debris flow occurrence. In 2020, aerial photogrammetry was performed using an unmanned aerial vehicle in Seonseri, Osan-myeon, and Gokseong-gun. The erosion and deposition areas owing to debris flow were estimated using the orthographic images generated from photogrammetry and high-resolution Digital Surface Mode (DSM), and the extent of debris flow was accurately estimated. For debris flow simulation, the LS-RAPID program, with the apparent friction angle of the Coulomb's friction model as an important factor, was applied. The simulation results were significantly affected by the quality of the topographical data. It is essential to apply DSM data for obtaining a highly accurate simulation of the deposition area where damage generally occurs. To evaluate the performance of the simulation, the LSSI index with the deposition area as a factor was applied; it was found to be 65%, showing a superior predictive performance. In conclusion, it is possible to predict the debris-flow damage using LS-RAPID simulation, and the DSM data on deposition areas are required to generate a reliable disaster map.