Glaciers and their changes based on Chinese glacier inventories in Ili River Basin, Xinjiang, northwestern China

The Ili River is a typical transboundary river between China and Kazakhstan, with glaciers within its basin serving as a crucial solid water resource. Recently, we compiled the Chinese Glacier Inventory of Xinjiang in 2020 (CGI-XJ2020) using high-resolution satellite imagery (<2 m), based on visual interpretation. This study presented the state of glaciers in the Ili River Basin in 2020 by utilizing the data from CGI-XJ2020. It quantified glacier changes in 1960s–2020 based on CGI-XJ2020 and revised datasets from the First and Second Chinese Glacier Inventories. The results indicated that in 2020, the Ili River Basin contained 2,177 glaciers, totaling 1,433.19 km 2 in area. Among them, 213 glaciers were covered by 57.43 km 2 of debris. The total uncertainty in glacier area was 46.43 km 2 , accounting for approximately 3.2% of the total area. Mapped glacier areas varied from 0.003 to 74.67 km 2 , with an average area of 0.66 km 2 and a median area of 0.15 km 2 . Glaciers <0.5 km 2 in size dominated in numbers, accounting for 75.1% of the total. Glaciers in the basin have undergone significant retreat during 1960s–2020, with their total area decreasing by 589.38 km 2 (29.15%). A total of 495 glaciers (with an area of 49.67 km 2 ) disappeared. The average annual glacier area retreat rates for 1960s−2007 and 2007–2020 were 10.86 km 2 /a (0.54%/a) and 9.41 km 2 / a (0.61%/a), respectively, showing a continued acceleration in glacier shrinkage, despite a slight decrease in absolute retreat rates.