Genetic types and distribution of glacial lakes in western Sichuan and eastern Tibet

Global warming has caused dramatic glacial lake expansions and increasing of glacial lake outburst floods (GLOFs) in western Sichuan and eastern Tibet (WSET), indicating that the spatial distribution of glacial lakes in this region need to be ascertained imminently.The overall distribution of glacial lakes of WSET during 2010-2020 has been mapped on the basis of different genetic types by manual visual interpretation method, which mainly involves glacial erosion lakes (GELs), moraine lakes (MLs), and barrier lakes (BLs).The results show that there are total 17737 glacial lakes inventoried in WSET with each area of greater than 50 m², including 11903 GELs, 5734 MLs and 100 BLs, covering a total area of 7.93×10³ km². Zayü County in Nyinchi, Tibet, as the most densely distributed county of glacial lakes, hosts 2161 glacial lakes, which account for 12.18% of the total number.Additionally, the glacial lakes in Shaluli Mountains and Yarlung Zangbo River basin are the most lake-concentrated ones, accounting for 29.10% (5161 lakes) and 30.73% (5450 lakes) of the total respectively.Meanwhile, GELs and MLs share the similar spatial distribution patterns, and are mostly concentrated at an altitude of 4500~5000 m (50.57% of the total), implying a glacier active area.Most of BLs (77% of the total BLs) are located at the altitude of 4000~5000 m, indicating a negative interaction with the glaciers.Combined with the comprehensive analysis of genetic types of glacial lakes and their relationships with the glaciers, 9 potential dangerous glacial lakes, including 7 MLs and 2 BLs, are preliminarily identified.Regarding the risk of GLOFs in the future, the focus researches, such as investigations, assessments, monitoring, and early warning, should be carried out in the construction and operation of the major infrastructures in WSET.