Abstract:

Using the two-phase remote sensing images based on the ETM in 1999 and the GF-1/OLI in 2014/2015 in the Qinghai-Tibet region, the glacial cataloging is completed and the glacial changes in the Chinese Himalayas during 1999-2015 is summarized. The results show that glaciers were generally retreating in the Himalayas from 1999 to 2015. There were 85 (1.53% of total)retreating glaciers with a total decrease in size and volume of 42.00 km²(0.67%)and 2.385 km³(0.50%), respectively.Along the Himalayas from east to west,the number of glaciers decreased more in the east, whereas the size and volume decreased more in the west with glaciers relatively stable in the middle.On one hand, the glaciers retreated in the north, northeast and east, with the loss of the number and size being the highest in the north, followed by the northeast and the east. Meanwhile, the reduction rate of the glacier number and size was the highest in the east and northeast, respectively, and lowest in the north. While the size decreased mostly in the average slope of 10° to 15°, the number decreased mostly in the slope of 30° to 35°. The glacial retreat was most significant at 5,500 to 6,000 m elevations, followed by 5,000 to 5,500 m.The reduction rate was the highest at 3,500 to 4,000 m elevations,and lowest at 6,000 to 6,500 m elevations.Decreases in the glacial number and size were obvious in the Yarlung Zangbo River Basin (5O2), followed by Langqin River Basin (5Q2)and Pengqu (5O1), but least in Zhari Nanmucuo (5Z3). The retreat or disappearance of a large number of smaller glaciers, accompanied by the retreat of larger ones, is the main cause of glacier changes in the Himalayas. There is a close relation between glacial retreat and climate change in the Himalayas. Analyzing the annual mean temperature and annual precipitation over the past decades, the annual average temperature has increased significantly since the 1961’s, whilst the annual precipitation has increased or decreased. The temperature rise and precipitation drop may have caused the glacial retreat in the survey period.

Key words: glacial change, glacier inventory, remote sensing, Himalayas