Abstract:
On 7 Feb 2021, a high-location glacier-rock avalanche and dammed the river, and late caused outburst flooding disaster on the Rich Ganges River in northern Chamoli, India, that destroyed hydropower stations and bridge facilities more than 20 kilometers downstream, and claimed nearly 200 deaths. This paper uses multi-period high-resolution remote sensing images to compare and analyze the characteristics of the landslide source area and accumulation area before and after the high-location ice rock landslide disaster in the Ganges River Basin of Chamoli, India, and preliminarily discuss the movement process of the landslide. The results show that before 2013, the creep displacement of the avalanche landslide was small, and the cracks in the ice and snow cover on the surface were not obvious. From 2013 to 2017, the creep displacement of avalanche landslides increased significantly, and as many as 62 ice cracks of various sizes were visible in the ice and snow cover, with the longest being 513 m. Satellite images on February 5, 2021 showed that these ice cracks had been connected and penetrated, with a maximum width of 15 m, and they were unstable and damaged on February 7. According to the post-sliding remote sensing image, the collapsed landslide was cut from 4 sets of large structural surfaces in different directions, with an area of about 0.32 km
2, an average thickness of about 70 m, and a volume of about 23×10
6 m
3. The collapsed landslide body loses stability and disintegrates and moves down the valley with a debris flow at high speed. Due to terrain blocking, some debris particles accumulate in the rapid terrain change zone and form a barrier dam. After the barrier dam body breaks, a mountain torrent disaster is formed.