Debris flow gully zoning and risk assessment based on numerical simulation

China China Institute of Geo-environmental Monitoring, Beijing, 100081

^* Zhen Feng fz14268@163.com

Abstract

In order to evaluate the zoning and risk of debris flow gully based on numerical simulation, a set of theoretical system and technical process of debris flow quantitative risk analysis suitable for mountainous towns in southwest China was constructed, taking buildings and roads as the research objects, in view of the particularity of disaster-bearing body types and debris flow disaster modes. It is mainly divided into three steps: (1) Using FLO-2D numerical model, the risk of debris flow is expressed by intensity index IDF; The simulation results of debris flow in Gully A 7·11 show that the area of correctly judged area is 50.02×10⁴m², the comprehensive accuracy index ω is 1.22, and the maximum IDF can reach 1013.25m³/s², showing a general trend that the upstream is higher than the downstream, and the center of the drainage channel is higher than both sides. Using the data of debris flow damage in A ditch 7·11 in A city, a material vulnerability curve based on the probability of exceeding loss is constructed. Based on the establishment of disaster-bearing body database, the expected loss of disaster-bearing body can be expressed quantitatively by setting different future debris flow scenarios. The model verification and case application of A ditch in A city show that the quantitative risk analysis system of debris flow can well reflect the response mechanism of disaster-bearing body and debris flow, and can provide scientific basis for disaster prevention and mitigation in debris flow threat areas.