Numerical simulation and analysis of a geological disaster chain in the Peilong valley, SE Tibetan Plateau

The Yarlung Tsangpo river basin in the southeastern part of the Tibetan Plateau contains many maritime glaciers, where the massive debris flow formation caused by the glacial degradation leads to the issue of regional warming. It often forms a continuous geological disaster chain. In this study, the topographical features and debris flow deposits in the Peilong valley were investigated in November 2018. It was found that the geological conditions in the valley are complex and numerous unstable sources are existed. Field investigations, laboratory tests, and a geomorphological analysis were conducted to obtain relevant data for the valley. And comparison of Landsat images indicates that the rate of change of the glacial area is 51.62% from winter to summer. Discrete element software (PFC3D) is used to simulate glacial landslides on the left bank. The simulation results show that a dam with a height of 141 m was formed, creating a lake. The debris flow after the dam break is simulated for different peak discharge values and durations based on a free surface shallow flow (SFLOW) model, with a final accumulation depth of 21.6 m. The comprehensive results of numerical simulation show that the chain of geological disasters induced by glacial landslide poses a huge threat to residents and roads near Peilong valley. Therefore, it is recommended to monitor the glacier activities in real time to enable forecasting of debris flows and reduce the property losses and prevent loss of life.