Combined numerical investigation of the Yigong rock slide-debris avalanche and subsequent dam-break flood propagation in
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Yu Zhuang I Yueping Yin I Aiguo Xing I Kaiping Jin
Combined numerical investigation of the Yigong rock slide-debris avalanche and subsequent dam-break flood propagation in Tibet, China
Abstract On April 9, 2000, a long run-out landslide occurred in Yigong, Bomi county, Yarlung Zangbo Grand Canyon, China. The displaced materials traveled approximately 10 km with an elevation difference of 3 km, and finally generated a barrier lake at the toe of the mountain. The landslide and the collapse of the associated landslide dam killed 30 people, left more than 100 people missing, and destroyed several bridges. A combined debris avalanche-dam break flood simulation was performed in this study to better understand the long run-out mechanism and behaviors of such an event. The dynamic model DAN3D was used to simulate the run-out process of the sliding mass, while the Computational Fluid Dynamics software FLOW-3D was used to simulate the duration of landslide dam break and subsequent outburst flood propagation. Output data from the DAN3D simulation were used as input parameters for landslide dam modeling in FLOW-3D. Simulated results indicated that the duration of the landslide movement was estimated at 300 s with a maximum velocity of 90 m/s. Also, the maximum flow of the outburst flood at the Tongmai bridge was approximately 130,000 m3/s. The observed phenomena and measured data in situ verified the validity of the numerical simulation. It is expected that the work conducted in this study could help improve the understanding of the chain disaster of the rock slide-debris avalanche and subsequent dambreak flood. Keywords Yigong landslide . Dam-break flood . Chain disaster . DAN3D . FLOW-3D . Dynamic analysis Introduction The Yarlung Zangbo Grand Canyon, located at the southeast margin of Tibetan Plateau, is the world’s deepest gorge with a range in elevation of more than 7000 m (Li et al. 2016). In the past decades, a massive number of landslides occurred in this area corresponding to the high seismic activity, active tectogenesis, and snow melting in this region (Fu et al. 2011; Qu et al. 2017; Du et al. 2017). Historical records indicate that more than 50 catastrophic long run-out landslides (with a volume over 10 Mm3) had occurred in this region and brought massive damage to the surrounding infrastructure and facilities (Delaney and Evans 2015; Du et al. 2019; Zhao et al. 2019). So far, a great deal of effort has been performed to mitigate and prevent the economic loss and casualties associated with such disasters, e.g., carrying out a detailed field investigation in disaster-prone areas and establishing risk assessment systems with weather forecasting (Yin et al. 2010; Xing et al. 2016). These efforts have significantly improved the accuracy of hazard prediction and mitigated casualties caused by disasters. The sliding mass of a long run-out landslide can reach incredibly high speed during the movement process and rapidly enters the water, and thus generating a landslide dam with high risk.
Globally, the outburst flood c
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