Scentific Research

Glacial lake outburst floods (GLOFs) are a severe hazard in the Himalayas. In recent years, with regional climate warming and glacier retreat, the glacial lakes in the Himalayas has expanded significantly and the risk of glacial lake outburst has increased. According to recent studies, regional glacial lake documenting and research on area changes are experiencing rapid development, but the investigation and research on lake volume are yet to be carried out, and we still need to improve our analysis on relevant disaster cases.

Based on remote sensing images and depth measurements using an unmanned surface vessel, the team of Ding Yongjian, a Researcher of the State Key Laboratory of Cryospheric Science, Chinese Academy of Sciences and the China-Pakistan Joint Research Center on Earth Sciences, surveyed and analyzed the area and volume of Jialong Co, a typical glacial lake in Poiqu River. The results showed that Jialong Co had experienced slow–quick–slow expansion in the past 30 years, increasing in area from 0.13 km² to 0.60 km², an increase of nearly four times. There is an obvious positive correlation between the change of glacial lake area and regional warming. Warming climate and retreating glaciers provide space for glacial lakes to develop. Since the mother glacier has retreated to a higher rock wall and is no longer directly connected to the glacial lake, Jialong Co will not expand again in the short term. The lake bathymetric map revealed that the lake volume was 3.75 × 10⁷ m³ in August 2020.

Through on-the-spot investigation, the researchers investigated and analyzed the disaster-inducing factors of glacial lakes. The deepening and widening of the outlet of glacial lake, the sudden release of glacial melting water in the upstream of Chongdui Gully and its erosion on lake dam, and the water erosion to and collapse of the downstream river bank may become key factors for the prevention and control of glacial lake disasters in the future.

The findings provide data for the expansion variations and volume detection of typical glacial lakes and cases for the investigation of potential hazard factors, and further promote our understanding on the development and hazard-inducing features of glacial lakes in the Himalayas. Dr. Li Da is the first author of the thesis, and Researcher Shangguan Donghui is the corresponding author. The research was funded by the Second Tibetan Plateau Scientific Expedition, the Strategic Priority Research Program of the Chinese Academy of Sciences, etc. The findings were published in the Science of the Total Environment with the title "Expansion and hazard risk assessment of glacial lake Jialong Co in the central Himalayas by using an unmanned surface vessel and remote sensing".

Link: https:// 10.1016/j.scitotenv.2021.147249