Dynamic analysis of moraine landslide–induced glacial lake outburst flood event
摘要
This study reconstructs a moraine landslide–induced glacial lake outburst flood (GLOF) in 2020, Jinwuco (lake name), Tibet, China, based on survey data and numerical modeling, revealing the dynamic process of the landslide entering the glacial lake, impulse wave propagation, terminal dam outburst, and flood evolution. Our findings first indicate that the interaction of the moraine landslide with a maximum velocity of 49.6 m/s with the lake generated an impulse wave with a height of 76.7 m. Further, the wave propagates to the terminal dam in 100 s and produces an impact force of about 4.26 × 1010 N on the breach. Following this, the flooding backwater phenomenon caused by the topographic conditions arises in the river valley, with a 188.4 × 103 m2 backwater area formed. Flood long-term evolution shows that the Jinwuco GLOF had a peak discharge of 5475 m3/s at the dam, with the lake level decreasing about 20.2 m in 200 min after the landslide release. Finally, the outburst flood traveled about 15.5 km and inundated an area of 8.44 × 106 m2, with a peak flood velocity and maximum depth of 39.5 m/s and 19.3 m, respectively. Multi-stage dynamic analysis results indicate that the floodwater momentum enhancement by experiencing an elevation drop (650 m) before it enters the valley is the turning point of the GLOF, which connects the pre-level disaster event and amplifies the impact of the GLOF, including the flood destructiveness and local economic loss. These findings contribute to clarifying the cascading mechanism of GLOFs beginning with an ordinary small-scale triggering event.