Glacier Variation in the Lenglongling Range of Eastern Qilian Mountains from 1972 to 2007

The Lenglongling Range of Eastern Qilian Mountains was selected as a sample region to search a method for delineating glacier extent by u-sing Topographic maps of 1972, Landsat TM image of 1994, CBERS-2 image of 2000 and ASTER image of 2007. Only the remote sensing images of warm season and free of clouds were selected. The glacier variation of Lenglong Range was investigated by comparing digitized glacier outlines from the Chinese Glacier Inventory (CGI) surveyed in 1972 and the remote sensing images. For delineating the extent of exposed glacier ice conveniently and efficiently from images, the Interactive Data Language (IDL) program by ITT Visual Information Solutions (ITT VIS) was used. The results show that the area of 244 glaciers in the Lenglong Range decreased by 12.796 km super(2) or 0.65% times a super(-1) from CGI to 1994, by 5.693 km super(2) or 1.05% times a super(-1) from 1994 to 2000, and by 5.797 km super(2) or 0.98% times a super(-1) from 2000 to 2007. From CGI to 2007, the total area lost wa