scholarly journals Reconstructing the History of Glacial Lake Outburst Floods (GLOF) in the Kanchenjunga Conservation Area, East Nepal: An Interdisciplinary Approach

2020 ◽  
Vol 12 (13) ◽  
pp. 5407
Author(s):  
Alton C. Byers ◽  
Mohan Bahadur Chand ◽  
Jonathan Lala ◽  
Milan Shrestha ◽  
Elizabeth A. Byers ◽  
...  
Keyword(s):  
Interdisciplinary Approach ◽  
Debris Avalanche ◽  
Field Investigation ◽  
Glacial Lake ◽  
High Mountain ◽  
Lateral Moraine ◽  
Conservation Area ◽  
Terminal Moraine ◽  
Outburst Floods ◽  
Glacial Lake Outburst Floods

An interdisciplinary field investigation of historic glacial lake outburst floods (GLOFs) in the Kanchenjunga region of Nepal was conducted between April and May, 2019. Oral history and field measurements suggested that at least six major GLOFs have occurred in the region since 1921. A remote sensing analysis confirmed the occurrence of the six GLOFs mentioned by informants, including two smaller flood events not mentioned that had occurred at some point before 1962. A numerical simulation of the Nangama GLOF suggested that it was triggered by an ice/debris avalanche of some 800,000 m3 of material, causing a surge wave that breached the terminal moraine and released an estimated 11.2 × 106 m3 ± 1.4 × 106 m3 of water. Debris from the flood dammed the Pabuk Khola river 2 km below the lake to form what is today known as Chheche Pokhari lake. Some concern has been expressed for the possibility of a second GLOF from Nangama as the result of continued and growing landslide activity from its right lateral moraine. Regular monitoring of all lakes and glaciers is recommended to avoid and/or mitigate the occurrence of future GLOF events in the region. Collectively, the paper demonstrates the benefits and utility of interdisciplinary research approaches to achieving a better understanding of past and poorly documented GLOF events in remote, data-scarce high mountain environments.

scholarly journals Simulation and Assessment of Future Glacial Lake Outburst Floods in the Poiqu River Basin, Central Himalayas

Water ◽  
2021 ◽  
Vol 13 (10) ◽  
pp. 1376
Author(s):  
Taigang Zhang ◽  
Weicai Wang ◽  
Tanguang Gao ◽  
Baosheng An
Keyword(s):  
River Basin ◽  
Hazard Assessment ◽  
Glacial Lake ◽  
High Mountain ◽  
Glacial Lakes ◽  
Central Himalayas ◽  
Outburst Floods ◽  
Glacial Lake Outburst Floods ◽  
Social And Economic Development ◽  
Glacial Lake Outburst Flood

A glacial lake outburst flood (GLOF) is a typical glacier-related hazard in high mountain regions. In recent decades, glacial lakes in the Himalayas have expanded rapidly due to climate warming and glacial retreat. Some of these lakes are unstable, and may suddenly burst under different triggering factors, thus draining large amounts of water and impacting downstream social and economic development. Glacial lakes in the Poiqu River basin, Central Himalayas, have attracted great attention since GLOFs originating there could have a transboundary impact on both China and Nepal, as occurred during the Cirenmaco GLOF in 1981 and the Gongbatongshaco GLOF in 2016. Based on previous studies of this basin, we selected seven very high-risk moraine-dammed lakes (Gangxico, Galongco, Jialongco, Cirenmaco, Taraco, Beihu, and Cawuqudenco) to simulate GLOF propagation at different drainage percentage scenarios (i.e., 25%, 50%, 75%, and 100%), and to conduct hazard assessment. The results show that, when any glacial lake is drained completely or partly, most of the floods will enter Nepal after raging in China, and will continue to cause damage. In summary, 57.5 km of roads, 754 buildings, 3.3 km2 of farmland, and 25 bridges are at risk of damage due to GLOFs. The potentially inundated area within the Chinese part of the Poiqu River basin exceeds 45 km2. Due to the destructive impacts of GLOFs on downstream areas, appropriate and effective measures should be implemented to adapt to GLOF risk. We finally present a paradigm for conducting hazard assessment and risk management. It uses only freely available data and thus is easy to apply.

scholarly journals Glaciers, glacial lakes and glacial lake outburst floods in the Mount Everest region, Nepal

2009 ◽  
Vol 50 (53) ◽  
pp. 81-86 ◽  
Author(s):  
Samjwal Ratna Bajracharya ◽  
Pradeep Mool
Keyword(s):  
Average Rate ◽  
Glacial Lake ◽  
High Mountain ◽  
Glacial Lakes ◽  
Mount Everest ◽  
The Past ◽  
Outburst Floods ◽  
Glacial Lake Outburst Floods ◽  
Himalayan Glaciers ◽  
Recent Climate

AbstractRecent climate changes have had a significant impact on the high-mountain glacial environment. Rapid melting of glaciers has resulted in the formation and expansion of moraine-dammed lakes, creating a potential danger from glacial lake outburst floods (GLOFs). Most lakes have formed during the second half of the 20th century. Glaciers in the Mount Everest (Sagamartha) region, Nepal, are retreating at an average rate of 10–59 ma–1. From 1976 to 2000, Lumding and Imja Glaciers retreated 42 and 34 ma–1, respectively, a rate that increased to 74 ma–1 for both glaciers from 2000 to 2007. During the past decade, Himalayan glaciers have generally been shrinking and retreating faster while moraine-dammed lakes have been proliferating. Although the number of lakes above 3500 m a.s.l. has decreased, the overall area of moraine-dammed lakes is increasing. Understanding the behaviour of glaciers and glacial lakes is a vital aspect of GLOF disaster management.

scholarly journals Numerical modelling of Glacial Lake Outburst Floods using physically based dam-breach models

2014 ◽  
Vol 2 (1) ◽  
pp. 477-533 ◽  
Author(s):  
M. J. Westoby ◽  
J. Brasington ◽  
N. F. Glasser ◽  
M. J. Hambrey ◽  
J. M. Reynolds ◽  
...  
Keyword(s):  
Rapid Development ◽  
Model Performance ◽  
Cumulative Distribution ◽  
Glacial Lake ◽  
High Mountain ◽  
Hydrodynamic Modelling ◽  
Dam Breach ◽  
Outburst Floods ◽  
Glacial Lake Outburst Floods ◽  
Physically Based

Abstract. The rapid development and instability of moraine-dammed proglacial lakes is increasing the potential for the occurrence of catastrophic Glacial Lake Outburst Floods (GLOFs) in high-mountain regions. Advanced, physically-based numerical dam-breach models represent an improvement over existing methods for the derivation of breach outflow hydrographs. However, significant uncertainty surrounds the initial parameterisation of such models, and remains largely unexplored. We use a unique combination of numerical dam-breach and two-dimensional hydrodynamic modelling, employed with a Generalised Likelihood Uncertainty Estimation (GLUE) framework to quantify the degree of equifinality in dam-breach model output for the reconstruction of the failure of Dig Tsho, Nepal. Monte Carlo analysis was used to sample the model parameter space, and morphological descriptors of the moraine breach were used to evaluate model performance. Equifinal breach morphologies were produced by parameter ensembles associated with differing breach initiation mechanisms, including overtopping waves and mechanical failure of the dam face. The material roughness coefficient was discovered to exert a dominant influence over model performance. Percentile breach hydrographs derived from cumulative distribution function hydrograph data under- or overestimated total hydrograph volume and were deemed to be inappropriate for input to hydrodynamic modelling. Our results support the use of a Total Variation Diminishing solver for outburst flood modelling, which was found to be largely free of numerical instability and flow oscillation. Routing of scenario-specific optimal breach hydrographs revealed prominent differences in the timing and extent of inundation. A GLUE-based method for constructing likelihood-weighted maps of GLOF inundation extent, flow depth, and hazard is presented, and represents an effective tool for communicating uncertainty and equifinality in GLOF hazard assessment. However, future research should focus on the utility of the approach for predictive, as opposed to reconstructive GLOF modelling.

scholarly journals Numerical modelling of glacial lake outburst floods using physically based dam-breach models

2015 ◽  
Vol 3 (1) ◽  
pp. 171-199 ◽  
Author(s):  
M. J. Westoby ◽  
J. Brasington ◽  
N. F. Glasser ◽  
M. J. Hambrey ◽  
J. M. Reynolds ◽  
...  
Keyword(s):  
Model Performance ◽  
Monte Carlo Analysis ◽  
Glacial Lake ◽  
Roughness Coefficient ◽  
High Mountain ◽  
Dam Breach ◽  
Outburst Floods ◽  
Glacial Lake Outburst Floods ◽  
Physically Based ◽  
Inundation Extent

Abstract. The instability of moraine-dammed proglacial lakes creates the potential for catastrophic glacial lake outburst floods (GLOFs) in high-mountain regions. In this research, we use a unique combination of numerical dam-breach and two-dimensional hydrodynamic modelling, employed within a generalised likelihood uncertainty estimation (GLUE) framework, to quantify predictive uncertainty in model outputs associated with a reconstruction of the Dig Tsho failure in Nepal. Monte Carlo analysis was used to sample the model parameter space, and morphological descriptors of the moraine breach were used to evaluate model performance. Multiple breach scenarios were produced by differing parameter ensembles associated with a range of breach initiation mechanisms, including overtopping waves and mechanical failure of the dam face. The material roughness coefficient was found to exert a dominant influence over model performance. The downstream routing of scenario-specific breach hydrographs revealed significant differences in the timing and extent of inundation. A GLUE-based methodology for constructing probabilistic maps of inundation extent, flow depth, and hazard is presented and provides a useful tool for communicating uncertainty in GLOF hazard assessment.

Debris Flows Resulting From Glacial-Lake Outburst Floods in Tibet, China

2010 ◽  
Vol 31 (6) ◽  
pp. 508-527 ◽  
Author(s):  
Peng Cui ◽  
Chao Dang ◽  
Zunlan Cheng ◽  
Kevin M. Scott
Keyword(s):  
Debris Flows ◽  
Glacial Lake ◽  
Outburst Floods ◽  
Glacial Lake Outburst Floods

Landslides in moraines as triggers of glacial lake outburst floods: example from Palcacocha Lake (Cordillera Blanca, Peru)

Landslides ◽  
2016 ◽  
Vol 13 (6) ◽  
pp. 1461-1477 ◽  
Author(s):  
J. Klimeš ◽  
J. Novotný ◽  
I. Novotná ◽  
B. Jordán de Urries ◽  
V. Vilímek ◽  
...  
Keyword(s):  
Glacial Lake ◽  
Cordillera Blanca ◽  
Outburst Floods ◽  
Glacial Lake Outburst Floods

scholarly journals Using satellite images to monitor glacial-lake outburst floods: Lago Cachet Dos drainage, Chile

2015 ◽  
Author(s):  
Beverly A. Friesen ◽  
Christopher J. Cole ◽  
David A. Nimick ◽  
Earl M. Wilson ◽  
Mark J. Fahey ◽  
...  
Keyword(s):  
Satellite Images ◽  
Glacial Lake ◽  
Outburst Floods ◽  
Glacial Lake Outburst Floods

What’s in a lake? Glacial Lake Outburst Floods in the Peruvian Andes.

2021 ◽  
Author(s):  
Joanne Wood ◽  
Stephan Harrison ◽  
Ryan Wilson ◽  
Neil Glasser ◽  
John Reynolds ◽  
...  
Keyword(s):  
Climate Change ◽  
Glacial Lake ◽  
Peruvian Andes ◽  
The Past ◽  
The Andes ◽  
Glacier Recession ◽  
Outburst Floods ◽  
Glacial Lake Outburst Floods ◽  
Lake Systems ◽  
Physical Components

<p>Climate change is resulting in mass loss and the retreat of glaciers in the Andes, exposing steep valley sides, over-deepened valley bottoms, and creating glacial lakes behind moraine dams. Glacial Lake Outburst Floods (GLOFs) present the biggest risk posed by glacier recession in Peru. Understanding the characteristics of lakes that have failed in the past will provide an aid to identifying those lakes that might fail in the future and narrow down which lakes are of greatest interest for reducing the risks to local vulnerable populations. </p><p>Using a newly created lake inventory for the Peruvian Andes (Wood et al., in review) and a comprehensive GLOF inventory (unpublished) we investigate lakes from which GLOFs have occurred in the past. This is to establish which physical components of the glacial lake systems are common to those lakes that have failed previously and which can be identified remotely, easily and objectively, in order to improve existing methods of hazard assessment.</p>

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