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The geological conditions in the upper reaches of the Jinsha River on the southeastern margin of the Qinghai–Tibet Plateau are extremely complex. Many paleo-landslides and lacustrine sediments were formed in this area under the synergistic effect of tectonic activity and climate. The study of old deposits is helpful for understanding paleoenvironment, paleoclimate, and river geomorphology evolution. This study addressed the Wangdalong landslide damming event as the object and implemented a detailed on-site investigation. The geological characteristics of the landslide body, sliding surface, source area, and lacustrine deposits are determined. The 3D topographic restoration and the SFLOW software were used to simulate landslide dynamics, and the geomorphological evolution sequence of the Wangdalong landslide is proposed. Based on the landslide dating, the mineral analysis of lacustrine sediments, and the numerical simulation, the landslide was determined to be the product of the synergistic effect of climate and structure, and an earthquake or a heavy rainfall was the most probable triggering factor of the landslide. This study established a systematic analysis of the landslide damming event, which has reference significance for similar research. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]