Assessment Risk of Evolution Process of Disaster Chain Induced by Potential Landslide in Woda

Abstract The Jinsha River basin in the upper reaches of the Yangtze River in China has strong geological activities, and there are many large-scale landslides around the two banks, which can easily lead to a flood hazard chain. The recent Wenchuan and Luding earthquakes have increased the probability of landslide collapse on the slopes of the Jinsha River and increased the risk of a large landslide-dam-break-flood hazard chain. The Woda landslide is ancient and in a slow deformation stage, and if the landslide revives, it may block rivers and cause outburst floods. This study simulated the dynamic process of large-scale landslide failure and landslide dam formation by the deep integration continuum method. The outburst flood due to the dam breach is calculated by combining the dammed lake flow model and the shallow water equation, which can simulate the evolution of the downstream flood process. The results show that after the Woda landslide blocks the river, a dam of about 68.1m can be formed, the water storage capacity of the dammed lake is about 7.10*108 m3, the peak flow of the burst can reach 4.4*104 m3/s, and the impact range after the burst can reach 140km. Downstream, submerged several downstream villages and towns and the Sichuan-Tibet Railway. The study found that the resistance coefficient of landslides can significantly affect the evolution process of the entire hazard chain. Reducing the resistance coefficient of landslides can largely increase the height of the landslide dam, amplifying the peak flow of the outburst flood and increasing the risk of downstream elements at risk at far.