Ice-dams, outburst floods, and movement heterogeneity of glaciers, Karakoram

Bhambri, Rakesh; Hewitt, Kenneth; Kawishwar, Prashant; Kumar, Amit; Verma, Akshaya; Snehmani,; Tiwari, Sameer K.; Misra, Anshuman

doi:10.1016/j.gloplacha.2019.05.004

Cited by 74 publications

(45 citation statements)

References 70 publications

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“…Active surges pose dangerous hazards for local communities, threatening destruction of critical infrastructure when ice overrides villages, roads, bridges, and trails. Furthermore, if the glacier advances across river valleys and forms an ice-dammed lake, it may result in devastating outburst floods [21][22][23][24] . Therefore, monitoring of glacier surges, ice-dammed lake formation and drainage is essential.…”

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confidence: 99%

“…In the Karakoram, a large surge-like behavioral spectrum of surface movement has been reported, but the processes controlling their evolution may differ on a glacier-by-glacier basis 20,[24][25][26][27] . The hydrological surges, referred to as classic surges in the literature [28][29][30] involve sudden onset with high maximum velocities, and low velocities following a rapid termination of the surge.…”

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confidence: 99%

“…Classic surges involve ten-to twenty-fold accelerations of ice movement. However, some recent work documents many cases of lesser, two-to three-fold, accelerations coupled with the longer 'quiescent phase' and leading to recognition of a spectrum, or different types, of unsteady or heterogeneous glacier motions 24,26,29 . Unsteady glacier flow complicates glaciologists' ability to make accurate assessments of individual glacier mass balances using in-situ observations because of the uncertain outcomes or significance of surge phase and quiescent phase flow.…”

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confidence: 99%

“…fluctuations in surface melt elevation. Several studies in the Karakoram have utilized remote sensing data to study glacier surge dynamics 19,20,[23][24][25][26][27]33,34 . More recently, Rashid et al 35 reported the recent surge of Shispare Glacier using remote sensing observations.…”

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confidence: 99%

“…This study mainly presented monthly changes in the surface displacement of Shispare Glacier using only Landsat 8 OLI data. However, due to cloud and snow conditions, this data source alone may fail to quantify rapid acceleration and deceleration of surface displacement 20,24 , which prove typical in the surge mechanism of Karakoram glaciers. Therefore, the aims of our study are (1) to improve the understanding of Shispare Glacier surge dynamics and (2) to compare with the dynamics of other glacier surges.…”

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confidence: 99%

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The hazardous 2017–2019 surge and river damming by Shispare Glacier, Karakoram

Bhambri

Watson

Hewitt

et al. 2020

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In 2017-2019 a surge of Shispare Glacier, a former tributary of the once larger Hasanabad Glacier (Hunza region), dammed the proglacial river of Muchuhar Glacier, which formed an ice-dammed lake and generated a small Glacial Lake Outburst Flood (GLOF). Surge movement produced the highest recorded Karakoram glacier surface flow rate using feature tracking (~18 ± 0.5 m d −1) and resulted in a glacier frontal advance of 1495 ± 47 m. The surge speed was less than reports of earlier Hasanabad advances during 1892/93 (9.3 km) and 1903 (9.7 km). Surges also occurred in 1973 and 2000-2001. Recent surges and lake evolution are examined using feature tracking in satellite images (1990-2019), DEM differencing (1973-2019), and thermal satellite data (2000-2019). The recent active phase of Shispare surge began in April 2018, showed two surface flow maxima in June 2018 and May 2019, and terminated following a GLOF on 22-23 June 2019. The surge likely had hydrological controls influenced in winter by compromised subglacial flow and low meltwater production. It terminated during summer probably because increased meltwater restored efficient channelized flow. We also identify considerable heterogeneity of movement, including spring/summer accelerations. Hasanabad was a surge-type glacier situated on the north flank of Hunza Valley in the Central Karakoram (Fig. 1). During most, but not all, of the 20th Century, the Shispare (or Shisper) and Muchuhar tributaries of the Hasanabad Glacier have been separated. Shispare Glacier recently gained attention of the media, scientific community, policy makers, and disaster response agencies when it surged, blocked the outlet stream of Muchuhar Glacier and formed a lake 1-5 (referred to hereafter as Shispare Lake), which then drained, and has recently begun reforming. Surge-type glaciers oscillate between brief (months to years) rapid flow and lengthy (tens to hundreds of years) slow flow or stagnation, which are called the 'active' (or 'surge') and 'quiescent' phases, respectively 6. In the former, a large volume of the glacier's mass is rapidly transferred from an upper 'reservoir zone' into the lower 'receiving zone. ' Conversely, in the quiescent phase, the lower glacier slowly stagnates, thins, and retreats, while the upper part builds mass towards another surge 6,7. Surging occurs in both temperate and polythermal glaciers 6-11. Earlier, two primary mechanisms were proposed to explain the change between surge and quiescent flow. (1) Thermally regulated surges generally switch from largely cold-based ice in quiescence, to warm-based ice during the surge (e.g., Monacobreen Glacier, Svalbard) 12. (2) Hydrological regulation (e.g., Variegated Glacier, Alaska) invokes switching from low water pressure in subglacial channels of temperate glaciers to high water pressure, usually with restructuring of subglacial drainage 8,11,13,14. However, more recently, a uniform model of surging has been proposed to integrate both processes under an enthalpy framework 7. The enthalpy balance theory explains...

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confidence: 99%

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confidence: 99%

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The hazardous 2017–2019 surge and river damming by Shispare Glacier, Karakoram

Bhambri

Watson

Hewitt

et al. 2020

Sci Rep

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Remote‐sensing‐based monitoring the dynamics of Kyagar Glacial Lake in the upstream section of Yarkant River, north Karakoram

et al. 2022

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Long-term monitoring of ice-dammed lakes is important for understanding the process of lake storage, development, and glacial outburst flood (GLOF). Based on remote sensing observations for the period 1972-2020, we obtained what is so far the most detailed reconstruction of the filling and draining of Kyagar Lake, a typical annually ice-dammed lake in the north Karakoram. We show that annually repeated lake fillings-drainings were detected by satellite observations during two periods: 1996-2009 and 2015-2020, while between 2009 and 2015 no obvious cycle occurred. These two intermitted periods with regular annual revival of lake outburst were likely related to the long-term cycle of glacier surge dynamics, namely two remarkable surge-induced terminus accelerations during 1995-1997 and 2014-2016. Following each surge, the maximum lake areas decreased by about 33% from 1996 to 2009 and by about 88% from 2015 to 2020. Combined with climatic warming and the thinning of the ice-dam, the storage capacity of Kyagar Lake will likely continue to decrease in the future, and the risk of lake outburst flood thus becomes lower. Repeated drainage following filling exacerbates the depletion of mass at the glacier terminal, leading to the cessation of storage and creating the conditions for the next glacial surge to occur, creating a long-term iteration of the surge process.Considering the uncertainty and intensified climate changes, it suggests that a close monitoring of the glacial lake development and glacier dynamics would be still important.

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