Analysis of Debris Flow Damage Using High-Resolution Topographical Data

Abstract

Mountain disasters, such as landslides and debris flows, are becoming more prevalent due to abnormal weather patterns. Debris flows, triggered by heavy rainfall, are causing escalating damage to residential areas and roads as they surge down mountain streams. In order to both mitigate this damage and comprehend the underlying causes of such mountain disasters, comprehensive field investigations were carried out in regions where debris flows had transpired. To establish spatial information for analyzing vulnerable areas, GIS data were employed. Additionally, precise measurements of the actual extent of debris flow in targeted zones were obtained through the utilization of terrestrial LiDAR scanning. Subsequently, the process of debris flow was replicated using FLO-2D, a numerical model designed for such scenarios. This simulation incorporated actual rainfall data that had precipitated debris flow incidents, as well as probability-based rainfall data corresponding to return periods of 30, 50, and 100 years. Key parameters, including flow depth, velocity, and diffusion area, were compared across different scenarios. The sedimentation area of the section where debris flow originated, as determined from terrestrial LiDAR scan data, was estimated to be approximately 21,300 square meters. The outcomes of the FLO-2D simulation revealed that the diffusion area for Case I was approximately 20,900 m2, while the simulated diffusion area for a 100-year return period was calculated to be 40,725 m2. Furthermore, flow depth, velocity and diffusion area exhibited a gradual incremental trend in simulation results.