Glacier Change in the Yigong Zangbo Basin, Tibetan Plateau, China

Abstract

Distinguishing debris-covered glaciers from debris-free glaciers is difficult when using only optical remote sensing images to extract glacier boundaries. According to the features that the surface temperature of debriscovered glacier is lower than surrounding objects, and higher than clean glaciers, glacial changes in the Yigong Zangbo basin was analyzed on the basis of visible, near-infrared and thermal-infrared band images of Landsat TM and OLI/TIRS in the support of ancillary digital elevation model (DEM). The results indicated that glacier area gradually declined from 928.76 km2 in 1990 to 918.46 km2 in 2000 and 901.51 km2 in 2015. However, debriscovered glacier area showed a slight increase from 63.39 km2 in 1990 to 66.24 km2 in 2000 and 71.16 km2 in 2015. During 25 years, the glacier length became shorter continuously with terminus elevation rising up. The area of moraine lakes in 1990 was 1.43 km2, which increased to 1.98 km2 in 2000 and 3.41 km2 in 2015. In other words, the total area of the moraine lakes in 2015 is 2.38 times of that in 1990. This increase in moraine lake area could be the result of accelerated glacier melt and retreat, which is consistent with the significant warming trend in recent decades in the basin.