Extreme mass wasting during 2021 Dhauli Ganga event in the Higher Himalaya: insight from the landscape

The slope instability and associated mass wasting are among the most efficient surface gradation processes in the bedrock terrain that produce dramatic landscape change and associated hazards. The wedge failure in periglacial Higher Himalaya terrain on 7th&#160;February in Chamoli, Uttarakhand (India) produced >1.5 km high rock avalanche, which amalgamated with the glacial debris on the frozen river bed produced massive debris flow along the high gradient Rishi Ganga catchment. The high-velocity debris flow and a surge of high flood led to extensive loss of life and infrastructures and issuing the extreme event flood warning along the Alakananda-Ganga river, despite there was no immediate extreme climatic event. The affected region is the locus of extreme mass wasting events associated with Glacial Lake Outburst Flood (GLOF) and Landslide Lake Outburst Flood (LLOF) in the recent past. We analyzed the landscape to understand its control on the 7th&#160;February 2021 Rishi Ganga event and briefly discuss other significant events in the adjoining region e.g. 1893/1970 Gohna Tal/Lake LLOF and 2013-Uttarakhand events in Chamoli, which have significance in understanding the surface processes in Higher Himalayan terrain.

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Sustained Impact of a Glacial Lake Outburst Flood on Winter Turbidity Regimes across the Land-Ocean Aquatic Continuum

10.5194/egusphere-egu21-16594 ◽

2021 ◽

Author(s):

Ian Giesbrecht ◽

Suzanne Tank ◽

Justin Del Bel Belluz ◽

Jennifer Jackson

Keyword(s):

Freshwater Ecosystems ◽

Glacial Lake ◽

Mass Wasting ◽

Outburst Flood ◽

Fisheries Resources ◽

Carbon Burial ◽

Source To Sink ◽

Creek Watershed ◽

Glacial Lake Outburst Flood ◽

The Impact

Rainforest rivers export large quantities of terrestrial materials from watersheds to the coastal ocean, with important implications for local ecosystems and global biogeochemical cycles. However, the impact of episodic disturbance on this process is a critical knowledge gap in our understanding of land-sea connections. Fjords represent a global hotspot for terrestrial carbon burial in marine sediments, yet the relative importance of typical riverine fluxes vs. mass wasting fluxes is uncertain and dynamic. Similarly, mass wasting events can generate both an instantaneous pulse and a sustained shift in the material export regime. Riverine sediment regimes also have important implications for freshwater ecosystems and fisheries resources. A recent mass wasting event in Bute Inlet &#8211; Homalco First Nation traditional territory and British Columbia, Canada &#8211; presents an important opportunity to quantify the sustained impact of such an infrequent large disturbance on the source-to-sink linkages between glacierized mountains, rivers, and fjords.On November 28, 2020, a landslide in the headwaters of the Elliot Creek watershed (118 km2) triggered a glacial lake outburst flood (GLOF) that eroded 3 km2 of forested land and exported large volumes of water and terrestrial materials to the lower reaches of the Southgate River watershed (1986 km2) and ultimately to the head of Bute Inlet. Here we assess river and ocean surface turbidity over four winter months following the event, in comparison to pre-event measurements taken across all seasons in recent years. River turbidity was measured on the Southgate River above and below the confluence of Elliot Creek, beginning in December 2020, and at the mouth of the Southgate and nearby Homathko Rivers prior to November 2020. Bute Inlet turbidity was measured (every month to two months) starting in May 2017.Prior to the GLOF event, Southgate River turbidity ranged from a low of 3.3 &#177; 0.4&#160;FNU in the winter to a high of 71.4 FNU in the summer meltwater period. Since the event, Southgate River turbidity has been consistently elevated &#8805;6 times background levels recorded above Elliot Creek. At the extreme, on January 13, 2021, seven weeks after the GLOF, Southgate River mean turbidity (105.2 &#177; 3.3&#160;FNU) was 32 times the background (3.3 &#177; 0.4&#160;FNU), equating to a sustained increase in wintertime turbidity that sometimes exceeds the historical summertime peak. Given the typical coupling of turbidity with discharge, we expect further increases in turbidity with the coming freshet of 2021; the first meltwater season following the GLOF. These results suggest the potential for a sustained shift in the seasonal turbidity regime of the Southgate River and the estuarine waters of Bute Inlet. The elevated turbidity signals broader changes to: sediment export and carbon burial, the depth and seasonality of light penetration, river water quality, and spawning habitat quality for anadromous fish. Ongoing monitoring will be used to characterize the duration, dynamics, and potential recovery of elevated turbidity regimes across the land-to-ocean aquatic continuum in Bute Inlet.

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Determining the Events in a Glacial Disaster Chain at Badswat Glacier in the Karakoram Range Using Remote Sensing

Remote Sensing ◽

10.3390/rs13061165 ◽

2021 ◽

Vol 13 (6) ◽

pp. 1165

Author(s):

Donghui Shangguan ◽

Da Li ◽

Yongjian Ding ◽

Jun Liu ◽

Muhammad Naveed Anjum ◽

...

Keyword(s):

Remote Sensing ◽

Debris Flow ◽

Reanalysis Data ◽

Mountain Range ◽

Outburst Flood ◽

Ice Flow ◽

Sequence Of Events ◽

Hindu Kush ◽

Disaster Chain ◽

Glacial Lake Outburst Flood

The Karakoram mountain range is prone to natural disasters such as glacial surging and glacial lake outburst flood (GLOF) events. In this study, we aimed to document and reconstruct the sequence of events caused by glacial debris flows that dammed the Immit River in the Hindu Kush Karakoram Range on 17 July 2018. We used satellite remote sensing and field data to conduct the analyses. The order of the events in the disaster chain were determined as follows: glacial meltwater from the G2 glacier (ID: G074052E36491N) transported ice and debris that dammed the meltwater at the snout of the G1 glacier (ID: G074103E36480N), then the debris flow dammed the Immit River and caused Lake Badswat to expand. We surveyed the extent of these events using remote sensing imagery. We analyzed the glaciers’ responses to this event chain and found that the glacial debris flow induced G1 to exhibit accelerating ice flow in parts of the region from 25 July 2018 to 4 August 2018. According to the records from reanalysis data and data from the automatic weather station located 75 km from Lake Badswat, the occurrence of this disaster chain was related to high temperatures recorded after 15 July 2018. The chains of events caused by glacially related disasters makes such hazards more complex and dangerous. Therefore, this study is useful not only for understanding the formation of glacial disaster chains, but also for framing mitigation plans to reduce the risks for vulnerable downstream/upstream residents.

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Potential Impact of Landslide and Debris Flow on Climate Extreme – A Case Study of Xindian Watershed in Taiwan

10.5194/nhess-2017-262 ◽

2017 ◽

Author(s):

Shih-Chao Wei ◽

Hung-Ju Shih ◽

Hsin-Chi Li ◽

Ko-Fei Liu

Keyword(s):

Debris Flow ◽

Extreme Event ◽

Extreme Rainfall ◽

Mountainous Area ◽

Chain Process ◽

Climate Extreme ◽

Sediment Volume ◽

River Bed ◽

Late 21St Century ◽

Landslides And Debris Flows

Abstract. Sedimentary produced and transported in mountainous area under extreme rainfall by climate change is a challenged issue in recent years, especially in a watershed scale. The scenario approach with coupled simulation by different models could be one of a solution for further discussion under warming climate. With properly model selection, the simulation of projected rainfall, landslide, and debris flow are integrated by fully connection between models. Moreover, a case in Xindian watershed upstream the capital of Taiwan is chose for studying, and two extreme scenarios in late 20th and late 21st century are selected for comparison on changing climate. With sequent simulation, the chain process and compounded disaster can be considered in our analysis. The potential effects of landslides and debris flows are compared between current and future, and the likely impact in selected watershed are discussed under climate extreme. Result shows the unstable sediment volume would enlarge 29 % in terms of projected extreme event. The river bed may have strong variation by serious debris flow and increase about 10 % elevation in main channel. These findings also highlight the increasing risk in stable water supply, isolated village effect, and other secondary disaster in this watershed. A practical reference could be provided by some critical information in our result for long-term adapted strategies.

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Erosion and morphology of a debris flow caused by a glacial lake outburst flood, Western Norway

Landslides ◽

10.1007/s10346-008-0118-3 ◽

2008 ◽

Vol 5 (3) ◽

pp. 271-280 ◽

Cited By ~ 102

Author(s):

Hedda Breien ◽

Fabio V. De Blasio ◽

Anders Elverhøi ◽

Kaare Høeg

Keyword(s):

Debris Flow ◽

Glacial Lake ◽

Outburst Flood ◽

Western Norway ◽

Glacial Lake Outburst Flood

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The 1988 glacial lake outburst flood in Guangxieco Lake, Tibet, China

Natural Hazards and Earth System Science ◽

10.5194/nhess-14-3065-2014 ◽

2014 ◽

Vol 14 (11) ◽

pp. 3065-3075 ◽

Cited By ~ 8

Author(s):

J.-J. Liu ◽

Z.-L. Cheng ◽

Y. Li

Keyword(s):

Debris Flow ◽

Discharge Rate ◽

Glacial Lake ◽

Outburst Flood ◽

Field Surveys ◽

Terminal Moraine ◽

Viscous Debris Flow ◽

Local Residents ◽

Glacial Lake Outburst Flood ◽

Major Factors

Abstract. The 1988 glacial lake outburst flood (GLOF) in Guangxieco Lake is studied based on geomorphological evidence, interviews with local residents, field surveys in 1990 and 2007, and satellite images from different years. The findings are as follows. (1) The outburst event was caused by two major factors, namely, intense pre-precipitation and persistent high temperatures before the outburst and the low self-stability of the terminal moraine dam as a result of perennial piping. (2) The GLOF, with the peak discharge rate of 1270 m3 s−1, evolved along Midui Valley in the following order: sediment-laden flow, viscous debris flow, non-viscous debris flow, and sediment-laden flood, which was eventually blocked by Palongzangbu River. (3) A comparison between the conditions during the outburst in 1988 and the present conditions suggests a small possibility of a future outburst unless drastic changes occur in landscape and climate. Reconstructing the outburst conditions and the GLOF processes is helpful in assessing a potential outburst in glacier lakes in Tibet.

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Weather Simulation of Extreme Precipitation Events Inducing Slope Instability Processes over Mountain Landscapes

Applied Sciences ◽

10.3390/app10124243 ◽

2020 ◽

Vol 10 (12) ◽

pp. 4243

Author(s):

Alessio Golzio ◽

Irene Maria Bollati ◽

Marco Luciani ◽

Manuela Pelfini ◽

Silvia Ferrarese

Keyword(s):

Debris Flow ◽

Wrf Model ◽

Meteorological Conditions ◽

Slope Instability ◽

Web Gis ◽

Precipitation Event ◽

Mass Wasting ◽

Variable Environment ◽

Extreme Precipitation Events ◽

Mountain Landscapes

Mountain landscapes are characterised by a very variable environment under different points of view (topography, geology, meteorological conditions), and they are frequently affected by mass wasting processes. A debris flow that occurred along the Croso stream, located in the Italian Lepontine Alps in the Northern Ossola Valley, during summer 2019, was analysed from a geological/geomorphological and meteorological point of view. The debris flow was triggered by an intense precipitation event that heavily impacted a very restricted area over the course of three hours. A previous debris flow along the same stream occurred in Autumn 2000, but it was related to an intense and prolonged rainfall event. The slope was characterised in terms of sediment connectivity, and data were retrieved and elaborated from the Web-GIS (Web-Geographic Information System) database of the IFFI-Italian Landslide Inventory and historical archives of landslides. Both the events were analysed through the weather research and forecasting (WRF) model applying a very high horizontal grid spacing with the aim of catching the precipitation patterns and timings. The obtained results are compared with the observed precipitation at a selection of weather stations in the area. The simulation of WRF that measured the timing in total precipitation and in its minor steps could be considered reliable. Moreover, it reveals to be appropriate for detecting in advance the meteorological conditions potentially triggering mass-wasting processes affecting slopes featuring high connectivity conditions and lithotypes characterised by a high Landslide Susceptibility Index.

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THE WEST SALT CREEK ROCK AVALANCHE, SAG POND, AND OUTBURST FLOOD: MORPHOLOGICAL AND SEDIMENTOLOGICAL SIGNATURES FROM A SERIES OF EXTRAORDINARY EVENTS

10.1130/abs/2017am-306710 ◽

2017 ◽

Author(s):

Jeffrey A. Coe ◽

◽

Erin K. Bessette-Kirton ◽

Rex L. Baum ◽

Joel B. Smith ◽

...

Keyword(s):

Rock Avalanche ◽

Outburst Flood ◽

The West ◽

Salt Creek

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Identification of Locations for Potential Glacial Lakes Formation using Remote Sensing Technology

Journal on Geoinformatics, Nepal ◽

10.3126/njg.v12i0.9068 ◽

2013 ◽

Vol 12 ◽

pp. 10-16

Author(s):

P Yagol ◽

A Manandhar ◽

P Ghimire ◽

RB Kayastha ◽

JR Joshi

Keyword(s):

Remote Sensing ◽

Glacial Lake ◽

Glacial Lakes ◽

Outburst Flood ◽

Remote Sensing Technology ◽

Sensing Technology ◽

Lake Formation ◽

Significant Area ◽

Glacial Lake Outburst Flood

In past Nepal has encountered a number of glacial lake outburst flood (GLOF) events causing loss of billions of rupees. Still there are a number of glacial lakes forming and there are chances of new glacial lake formation. Hence there is intense need to monitor glaciers and glacial lakes. The development on remote sensing technology has eased the researches on glacier and glacial lakes. Identification of locations of potential glacial lakes through the use of remote sensing technology has been proven and hence is opted for identification of locations of potential glacial lake in Khumbu Valley of Sagarmatha Zone, Nepal. The probable sites for glacial lake formation are at Ngojumpa, Lobuche, Khumbu, Bhotekoshi, Inkhu, Kyasar, Lumsumna, etc. As per study, the biggest glacial lake could form at Ngozumpa glacier. Even in other glaciers potential supra-glacial lakes could merge together to form lakes that occupy significant area. Nepalese Journal on Geoinformatics -12, 2070 (2013AD): 10-16

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The 2020 glacial lake outburst flood at Jinwuco, Tibet: causes, impacts, and implications for hazard and risk assessment

10.5194/tc-2020-379 ◽

2021 ◽

Author(s):

Guoxiong Zheng ◽

Martin Mergili ◽

Adam Emmer ◽

Simon Allen ◽

Anming Bao ◽

...

Keyword(s):

Time Lag ◽

Peak Discharge ◽

Glacial Lake ◽

Lateral Moraine ◽

Process Chain ◽

Outburst Flood ◽

Impact Wave ◽

Debris Landslide ◽

Property Losses ◽

Glacial Lake Outburst Flood

Abstract. We analyze and reconstruct a recent Glacial Lake Outburst Flood (GLOF) process chain on 26 June 2020, involving the moraine-dammed proglacial lake Jinwuco (30.356° N, 93.631° E) in eastern Nyainqentanglha, Tibet, China. Satellite images reveal that from 1965 to 2020, the surface area of Jinwuco has expanded by 0.2 km2 (+56 %) to 0.56 km2, and subsequently decreased to 0.26 km2 (‒54 %) after the GLOF. Estimates based on topographic reconstruction and sets of published empirical relationships indicate that the GLOF had a volume of 10 million m3, an average breach time of 0.62 hours, and an average peak discharge of 5,390 m3/s at the dam. Based on pre- and post-event high-resolution satellite scenes, we identified a large progressive debris landslide originating from western lateral moraine, having occurred 5–17 days before the GLOF. This landslide was most likely triggered by extremely heavy, south Asian monsoon-associated rainfall in June. The time lag between the landslide and the GLOF suggests that pre-weakening of the dam due to landslide-induced outflow pushed the system towards a tipping point, that was finally exceeded following subsequent rainfall, snowmelt, a secondary landslide, or calving of ice into the lake. We back-calculate part of the GLOF process chain, using the GIS-based open source numerical simulation tool r.avaflow. Two scenarios are considered, assuming a debris landslide-induced impact wave with overtopping and resulting retrogressive erosion of the moraine dam (Scenario A), and retrogressive erosion due to pre-weakening of the dam without a major impact wave (Scenario B). Both scenarios yield plausible results which are in line with empirically derived ranges of peak discharge and breach time. The breaching process is characterized by a slower onset and a resulting delay in Scenario B, compared to Scenario A. Evidence, however, points towards Scenario B as a more realistic possibility. There were no casualties from this GLOF but it caused severe destruction of infrastructure (e.g. roads and bridges) and property losses in downstream areas. Given the clear role of continued glacial retreat in destabilizing the adjacent lateral moraine slopes, and directly enabling the landslide to deposit into the expanding lake body, the GLOF process chain under Scenario B can be robustly attributable to anthropogenic climate change, while downstream consequences have been enhanced by the development of infrastructure on exposed flood plains. Such process chains could become more frequent under a warmer and wetter future climate, calling for comprehensive and forward-looking risk reduction planning.

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