Annual 30-meter Dataset for Glacial Lakes in High Mountain Asia from 2008 to 2017

Abstract

Climate change is intensifying glacier melting and lake development in High Mountain Asia (HMA), which could increase glacial lake outburst flood hazards and impact water resource and hydroelectric power management. However, quantification of variability in size and type of glacial lakes at high resolution has been incomplete in HMA. Here, we developed a HMA Glacial Lake Inventory (Hi-MAG) database to characterize the annual coverage of glacial lakes from 2008 20 to 2017 at 30 m resolution using Landsat satellite imagery. It is noted that a rapid increase in lake number and moderate area expansion was influenced by a large population of small glacial lake (≤0.04km 2 ), and faster growth in lake number occurred above 5300 m elevation. Proglacial lake dominated areas showed significant lake area expansion, while unconnected lake dominated areas exhibited stability or slight reduction. Small glacial lakes accounted for approximately 15% of the lake area in Eastern Hindu Kush, Western Himalaya, Northern/Western Tien Shan, and Gangdise Mountains, but contributed >50% of 25 lake area expansion in these regions over a decade. Our results demonstrate proglacial lakes are a main contributor while small glacial lakes are an overlooked element to recent lake evolution in HMA. Regional geographic variability of debris cover, together with trends in warming and precipitation over the past few decades, largely explain the current distribution of supra-and proglacial lake area across HMA. The Hi-MAG database are available at: https://doi.org/10.5281/zenodo.3700282 (Chen et al., 2020), it can be used for studies on glacier-climate-lake interactions, glacio-hydrologic models, glacial lake 30 outburst floods and potential downstream risks and water resources.

Glacial Lakes Mapping Using Multi Satellite PlanetScope Imagery and Deep Learning

“…Figure 11. Comparison of the mapped supraglacial lakes with the glacial lake inventory of HMA [36], Hi-MAG database [61] and glacial lakes inventory of CPEC [62]. Surprisingly, the Hi-MAG and CPEC inventories have not detected supraglacial lakes on the Baltoro glacier.…”

“…The sizes of the supraglacial lakes on the Baltoro glacier mapped using PlanetScope imagery of different dates are given in Table 3. We then used the following inventories for comparison: (1) glacial lakes inventory of High Mountain Asia [36], (2) A dataset of glacial lakes in High Mountain Asia (Hi-MAG) from 2008 to 2017 [61] and (3) glacial lakes in the China-Pakistan Economic Corridor (CPEC) [62]. These three inventories have been derived from Landsat-8 imagery (recent years).…”

“…The minimum mapping area of (1) is 0.0054 km 2 (2) is 0.0081 km 2 and (3) is 0.01 km 2 . These inventories have relied on manual [36] or semi-automatic [61,62] techniques for delineation of glacial lakes using Landsat imagery. The comparison of the supraglacial lakes is presented in Figure 11 and Table 4, which shows that several lakes have been missed in the inventory [36] and the inventories [61,62] have not detected lakes on the Baltoro glacier even though the data in Table 3 suggest that a significant number of lakes have an area greater than the minimum mapping area of these inventories.…”

“…We thank Tobias Bolch and Sonam Wangchuk from University of St Andrews, UK for sharing the GLakeMap results and for their feedback and comments. We would also like to thank the authors of the glacial lake inventories [36,61,62] and Adam Emmer, University of Graz, Austria for sharing their datasets. We thank Akiko Sakai from Ngoya University, Japan for providing the GAMDAM inventory data.…”

Comment on tc-2020-372

“…We compared our lakes and pond extents with two existing glacial lakes databases constructed from the same year (2015 Landsat): the HMA v.1 lake dataset, derived using a normalized difference water index (Shugar, 2020b) and HI-MAG constructed using a modified NDWI and manual corrections (Chen et al, 2020). A comparison with other global databases such as the Global Surface Water (GSW) (Pekel et al, 2016) was not undertaken here, as this has already been shown to underestimate the water occurrence over most of the Himalaya by Chen et al (2020). With regards to HMA v1 and HI-MAG datasets, Figure 13 shows that the lake outlines obtained from spectral unmixing in this study are outperforming both of the existing databases.…”