Progress on third glacier inventory of Xinjiang Uygur Autonomous Region (XUAR), northwestern China

Abstract

There are nearly half of the glaciers in China distributed in the Xinjiang Uygur Autonomous Region (XUAR) in northwestern China, where the largest glacierized centers outside polar region are nourished by the highest mountain ranges on earth such as Karakoram, western Kunlun mountains, eastern Pamir and Tianshan etc. Glaciers are water tower in this vast arid land in northwestern China. Up-to-date glacier inventory is highly demanded. Based on the latest glacier inventory compilation techniques including those for the first and second Chinese glacier inventories, we currently compiled the third glacier inventory of XUAR, named as Chinese Glacier Inventory of Xinjiang 2020 (CGI-X2020). Comparing to the second Chinese glacier inventory (CGI-2), three improvement has been made in the CGI-X2020. Firstly, CGI-X2020 is based on a total of 235 scenes Chinese satellite imageries were selected out of 30,000 ：ZY1 (5); ZY3 (59);  GF1 (135); GF2 (1) ; GF7 (2) and GF6 (33) during the period 2018-2021, mainly during 2020 summer, having a resolution better the 2 m, whereas CGI-2 was based on Landsat TM/ETM+ imageries acquired during 2006–09 with a resolution of 30 m. Secondly, the glacier volume (an important parameter of the glacier inventory) was computed by scaling method which was validated by 22 in-suit glacier thickness measurements through GPR cross glacierized region in XUAR by our research team. Thirdly, the debris coverage of the glaciers were better identified on the basis of high-resolution imageries. According to GIX2020, by 2020, there are 24,448 glaciers in XUAR, covering an area of 23,531.65 km2 with a total volume about 1548.80 km3  ; There are 20,586 glaciers with an area smaller than 1km2, but the area and volume occupy only 19.16% and 7.95%. Glacier volume in Tarim basin accounts for 64.72% of that in total river systems; The glacier volume is distributed in Kunlun Mountains, followed by Tien Shan and Karakoram Mountains, respectively; 30.68% and 23.92% of the total glacier volume are distributed in Kashgar and Hotian region, respectively.