Retreat rates of debris-covered and debris-free glaciers in the Koshi River Basin, central Himalayas, from 1975 to 2010
Debris-covered glaciers are common in the Himalayas and play a key role in understanding future regional water availability and management. Previous studies of regional glacial changes have often neglected debris-covered glaciers or have mixed them with debris-free glaciers. In this study, we generated a new glacier data set that includes debris-covered and debris-free glaciers to study the glacial surface area change in the Koshi River Basin in the central Himalayas. Long time-series Landsat data were used to extract the glacier boundaries using automatic and manual classification methods. The glacial area decreased by 10.4% from 1975 to 2010 at a rate of 0.30% a−1, with accelerated melting since 2000 (0.47% a−1). Small glaciers melted faster than large glaciers. In terms of distinctive glacier types, debris-free glaciers shrank at a rate of 0.45% a−1, faster than debris-covered glaciers (0.18% a−1), while debris-covered glaciers larger than 5.0 km2 retreated at a rate faster than debris-free glaciers of the same-sized group. We also studied the potential interactions between 222 supraglacial lakes and debris-covered glaciers. Debris-covered glaciers with glacial lakes melt faster than glaciers without lakes. This study can improve our understanding of the differences in the changes between debris-covered and debris-free glaciers in the central Himalayas and help evaluate water resource changes in the Himalayas.
KeywordsGlacier change Debris-covered glacier Debris-free glacier Glacial lake Koshi River Basin Central Himalayas
This study was funded by the National Natural Science Foundation of China (41190081, 41401082, 41571061 and 41701069), the Strategic Priority Research Program (B) of the Chinese Academy of Sciences (XDB03030203) and the Major Special Project—The China High-Resolution Earth Observation System (30-Y30B13-9003-14/16-01). We would like to thank Dr. Xiaoxin Yang for the helpful comments on the earlier draft of this paper. We are grateful to the anonymous reviewers for their valuable comments and advices in improving the manuscript. We also thank the U.S. Geological Survey (USGS) for providing Landsat data.
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