Abstract: Glaciers and glacial lakes are well developed in the Koshi River basin. With global warming, glacial meltwater has become an important source of glacial lake expansion. At the same time, it will cause natural disasters such as glacial lake outburst flood (GLOF). Therefore, it is significant to study the temporal and spatial changes of glacial lakes in the region. In this paper, based on Landsat series remote sensing images and digital elevation model, the temporal and spatial distribution and variation characteristics of glacial lake area in the Koshi River basin From 1990 to 2020 are analyzed. The results show that: ① From 1990 to 2020, the glacier area in the Koshi River basin showed an accelerating trend of retreat and the trend of accelerated retreat has been further strengthened in the past ten years. ②The glaciers in the Koshi River basin are mainly distributed at an altitude of 4800～6800m, with a slope of 5～20°.③ From 1990 to 2020, the glacial lakes in the Koshi River basin have shown an accelerated expansion trend. The area of glacial lakes has expanded by 26.09km². The glacial lakes with an area of >0.25km² expanded rapidly. The area of glacial lakes connected to glaciers has expanded significantly, with an area growth rate of 49.39%.④ From 1990 to 2020, a total of 11 glacial lakes in the Koshi River basin have burst, and some glacial lakes have completely burst or repeatedly burst. The area of glacial lakes is 0.02～0.7km². ⑤From 1990 to 2020, the temperature and precipitation in the Koshi River basin showed a fluctuating growth trend resulting in accelerated retreat of glaciers, accelerated expansion of glacial lakes, and frequent occurrence of glacial lake outburst flood in the Koshi River basin.

Key words: Koshi River basin, glacier retreat, glacial lake expands, climate response, glacial lake outburst flood