Decadal glacial lake changes in the Koshi basin, central Himalaya, from 1977 to 2010, derived from Landsat satellite images

Shrestha, Finu; Gao, Xiao; Khanal, Narendra Raj; Maharjan, Sudan Bikash; Shrestha, Rajendra Bahadur; Wu, Lizong; Mool, P. K.; Bajracharya, Samjwal Ratna

doi:10.1007/s11629-016-4230-x

Cited by 27 publications

(17 citation statements)

References 35 publications

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“…Lake changes in Ladakh show a heterogeneous pattern varying from increasing to decreasing lake sizes and recurrent fluctuations. This is similar to observations made by Ashraf et al (2017) for the adjacent Karakoram, by Shrestha et al (2017) for the Koshi basin and by Nie et al (2018) along the Himalayan arc.…”

Section: Discussionsupporting

confidence: 90%

Cryosphere hazards in Ladakh: the 2014 Gya glacial lake outburst flood and its implications for risk assessment

et al. 2020

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This article attempts to reconstruct the causes and consequences of the 2014 glacial lake outburst flood (GLOF) event in Gya, Ladakh. We analyse the evolution of the Gya glacial lake using a high temporal and high spatial resolution remote sensing approach. In order to frame the case study in a larger picture, we produce a comprehensive inventory of glacial lakes for the entire Trans-Himalayan region of Ladakh. Changes in the extent and number of glacial lakes have been detected for the years 1969, 1993, 2000/02 and 2018 in order to assess the potential risk of future GLOFs in the region. The remote sensing approach was supported by field surveys between 2014 and 2019. The case study of the Gya GLOF illustrates the problem of potentially hazardous lakes being overlooked in inventories. The broader analysis of the Ladakh region and in-depth analysis of one GLOF lead us to propose an integrated approach for detecting undocumented GLOFs. This article demonstrates the necessity for using multiple methods to ensure robustness of risk assessment. The improved understanding can lead to a more accurate evaluation of exposure to cryosphere hazards and identification of alternative mechanisms and spatial patterns of GLOFs in the Himalaya.

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Section: Discussionsupporting

confidence: 90%

Cryosphere hazards in Ladakh: the 2014 Gya glacial lake outburst flood and its implications for risk assessment

et al. 2020

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“…The shadow and cloudiness in the high mountain areas with a monsoon climate complicated the selection of cloud and shadow free satellite data. The Landsat scenes acquired were from the post-monsoon season because the sizes of glacial lakes are stationary and changes are minor just after monsoon season; further, this season has less cloud cover and perennial snow coverage [9,36,48,49]. The acquired Landsat scenes of the study area had low cloud coverage (less than 10%) or were cloud-free.…”

Section: Datamentioning

confidence: 99%

“…Compared with other regional studies [1,9], the glacial lakes in the Nepal Himalaya account for~27% and~15% of the total number and area of glacial lakes, respectively, in the third pole, and~31% and~18% of the total number and area of glacial lakes, respectively, in the entire Himalaya (Table 4). A recent study of glacial lakes in the Koshi river basin overestimated the total number and area of the lakes because it did not apply a threshold for the maximum glacier-lake distance to map glacial lakes, and also, the quality control and assurance procedures were not explained [48].…”

Section: Mapping and Comparison With The Previous Studiesmentioning

confidence: 99%

Glacial Lakes in the Nepal Himalaya: Inventory and Decadal Dynamics (1977–2017)

2018

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Himalayan glaciers, in general, are shrinking and glacial lakes are evolving and growing rapidly in number and size as a result of climate change. This study presents the latest remote sensing-based inventory (2017) of glacial lakes (size ≥0.0036 km2) across the Nepal Himalaya using optical satellite data. Furthermore, this study traces the decadal glacial lake dynamics from 1977 to 2017 in the Nepal Himalaya. The decadal mapping of glacial lakes (both glacial-fed and nonglacial-fed) across the Nepal Himalaya reveals an increase in the number and area of lakes from 1977 to 2017, with 606 (55.53 ± 16.52 km2), 1137 (64.56 ± 11.64 km2), 1228 (68.87 ± 12.18 km2), 1489 (74.2 ± 14.22 km2), and 1541 (80.95 ± 15.25 km2) glacial lakes being mapped in 1977, 1987, 1997, 2007, and 2017, respectively. Glacial lakes show heterogeneous rates of expansion in different river basins and elevation zones of Nepal, with apparent decadal emergences and disappearances. Overall, the glacial lakes exhibited ~25% expansion of surface areas from 1987 to 2017. For the period from 1987 to 2017, proglacial lakes with ice contact, among others, exhibited the highest incremental changes in terms of number (181%) and surface area (82%). The continuous amplified mass loss of glaciers, as reported in Central Himalaya, is expected to accompany glacial lake expansion in the future, increasing the risk of glacial lake outburst floods (GLOFs). We emphasize that the rapidly increasing glacial lakes in the Nepal Himalaya can pose potential GLOF threats to downstream population and infrastructure.

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“…Several previous studies were conducted in the Nepal Himalaya, focusing on the development of such lakes (e.g., [31,[34][35][36]), hazard assessments (e.g., [13,30,34,37,38]), and community involvement in glacial lake research (e.g., [39,40]). Most of these studies demonstrated the development of glacial lakes usually on a decadal basis [8,41,42], and were regionally aggregated [11]. Furthermore, these studies were glacier or lake specific [13,24,43,44] or used one time satellite imagery [45].…”

Section: Introductionmentioning

confidence: 99%

Development of Supraglacial Ponds in the Everest Region, Nepal, between 1989 and 2018

Chand

Watanabe

2019

Remote Sensing

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Several supraglacial ponds are developing and increasing in size and number in the Himalayan region. They are the precursors of large glacial lakes and may become potential for glacial lake outburst floods (GLOFs). Recently, GLOF events originating from supraglacial ponds were recorded; however, the spatial, temporal, and seasonal distributions of these ponds are not well documented. We chose 23 debris-covered glaciers in the Everest region, Nepal, to study the development of supraglacial ponds. We used historical Landsat images (30-m resolution) from 1989 to 2017, and Sentinel-2 (10-m resolution) images from 2016 to 2018 to understand the long-term development and seasonal variations of these ponds. We also used fine-resolution (0.5–2 m) WorldView and GeoEye imageries to reveal the high-resolution inventory of these features and these images were also used as references for accuracy assessments. We observed a continuous increase in the area and number of ponds from 1989–2017, with minor fluctuations. Similarly, seasonal variations were observed at the highest ponded area in the pre- and postmonsoon seasons, and lowest ponded area in the winter season. Substantial variations of the ponds were also observed among glaciers corresponding to their size, slope, width, moraine height, and elevation. The persistency and densities of the ponds with sizes >0.005 km2 were found near the glacier terminuses. Furthermore, spillway lakes on the Ngozompa, Bhote Koshi, Khumbu, and Lumsamba glaciers were expanding at a faster rate, indicating a trajectory towards large lake development. Our analysis also found that Sentinel-2 (10-m resolution) has good potential to study the seasonal changes of supraglacial ponds, while fine-resolution (<2 m) imagery is able to map the supraglacial ponds with high accuracy and can help in understanding the surrounding morphology of the glacier.

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Decadal glacial lake changes in the Koshi basin, central Himalaya, from 1977 to 2010, derived from Landsat satellite images

Cited by 27 publications

References 35 publications

Cryosphere hazards in Ladakh: the 2014 Gya glacial lake outburst flood and its implications for risk assessment

Cryosphere hazards in Ladakh: the 2014 Gya glacial lake outburst flood and its implications for risk assessment

Glacial Lakes in the Nepal Himalaya: Inventory and Decadal Dynamics (1977–2017)

Development of Supraglacial Ponds in the Everest Region, Nepal, between 1989 and 2018

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