Abstract
Many debris-covered glaciers are broadly distributed across High Mountain Asia and have made a number of contributions to water circulation for Qinghai-Tibet Plateau (QTP). The formation of large supraglacial lakes poses risks for glacier lake outburst floods (GLOFs). Therefore, it is important to monitor the movement of glaciers and to analyze their spatiotemporal characteristics. In this study we take Cuolangma glaciers in the central Himalayas as study targets, where glacier No.1 is a lake-terminating debris-covered glacier and glacier No.2 is a land-terminating debris-covered glacier. The 3D deformation time series is firstly estimated by using the Pixel Offset-Small Baseline Subsets (PO-SBAS) based on the ascending and descending Sentinel-1 datasets spanning from January to December 2018. Then the horizontal and vertical time series displacements are obtained to show their spatiotemporal features. The velocities of glacier No.1 in horizontal and vertical direction were up to 16.0 ± 0.04 m/year and 3.4 ± 0.42 m/year, respectively, and the ones of the glacier No.2 were 12.0 ± 0.07 m/year and 2.0 ± 0.27 m/year, respectively. Next, the correlation between the precipitation and the surface velocity suggests that the glacier velocity does not show a clear association with daily precipitation alone. Finally, the debris-covered glaciers evolution is evaluated which shows that the tongue of the glacier No.1 is wasting away and the transition of glacier No.2 from land-terminating to lake-terminating is a probable scenario in the later period of glacier wastage. This research can significantly serve for glacier multidimensional monitoring and the mitigation of hazardous disaster caused by debris-covered glaciers in the central Himalayas.
Highlights
Mountain glaciers are one of the most sensitive natural indicators for climate changes in the Himalayas [1]
Debris-covered glaciers play a significant role in water-cycles in High Mountain Asia (HMA), altering glacier melting and their spatial patterns [2]
Shrinking of Himalayan debris-covered glaciers poses challenges to societies, such as the increasing changes of seasonal runoff caused by the glacier melting and the increasing risk of glacier lake outburst floods (GLOFs) caused by the expansion of unstable glacial lakes [3]
Summary
Mountain glaciers are one of the most sensitive natural indicators for climate changes in the Himalayas [1]. The percentage of debris-covered glaciers are roughly 10% in the Himalayas [2] and their tongues are generally situated in the lowest elevation with the increasing number of glacial lakes at the terminate [4]. Phase-based InSAR and amplitude-based pixel-tracking methods have become significant instrument to study glacier movement in a tradition, low-priced manner [17]. It is fundamental to comprehend the full 3D flow pattern for interpreting of debris-covered glacier movement and recognizing their evolution process [26]. What was the 3D debris-covered glacier deformation pattern and how did it change with time? We derive 3D time series displacement of two different terminus types of Cuolangma glaciers in the central Himalayas by applying PO-SBAS methods with Sentinel-1 imagery. A general explanation for evolution of debris-covered glaciers will trace the development of a glacial lake, verifying the role of lake-terminating debris-covered glacier in catastrophic disaster
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