Changes in glacier volume in the north bank of the Bangong Co Basin from 1968 to 2007 based on historical topographic maps, SRTM, and ASTER stereo images

Heterogeneous mass wastage has been found across the northwestern Tibet Plateau, and both slight positive and negative average mass budgets were observed using different data sets during the past decades. The north bank of the Bangong Co Basin partly covers the Western Kunlun Mountains and Karakoram Mountains. The assessment of glacier mass budget in this region over a long period is of particular interest to understanding the regional diversity of the mass changes of glaciers. Changes in glacier mass in the area of concern were assessed by differentiation of digital elevation models (DEMs) from the earliest available topographic maps, the Shuttle Radar Terrain Mission (SRTM), and the Advanced Space-borne Thermal Emission and Reflection Radiometer (ASTER) stereo images. Results show that glaciers in this basin have in general experienced a decelerated mass loss but with regional differences. Glaciers were found to have lost a volume of 4.45 +/- 0.63 km(3) from 1968 to 2007, corresponding to -0.18 +/- 0.03 m a(-1) water equivalent (w.e.) in the north bank of the Bangong Co Basin. Loss of glacier mass in this region from 1999 to 2007 was 0.11 +/- 0.12 m w.e. a(-1), which was approximately half the loss that occurred from 1968 to 1999 (-0.20 +/- 0.01 m w.e. a(-1)). From 1968 to 1999, higher mass losses were found in the north with smaller losses in the south, while from 1999 to 2007 there was more loss of mass in the southeast and a somewhat balanced mass budget in the northeast.