Evaluating the growth characteristics of a glacial lake and its degree of danger of outburst flooding: Imja Glacier, Khumbu Himal, Nepal

Watanabe, Teiji; Lamsal, Damodar; Ives, Jack D.

doi:10.1080/00291950903368367

Cited by 85 publications

(100 citation statements)

References 31 publications

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“…Scholars have proposed appropriate indicators to qualitatively evaluate the breach probabilities of MDLOFs according to the characteristics of the morainedammed lakes. The indicators mainly involve the freeboard of the lake, moraine dam, parent glacier, lake basin settings, and climatic background (Lv et al, 1999;Huggel et al, 2004;Watanabe et al, 2009;Janský et al, 2010). In recent years, much progress has been made on semi-quantitative and quantitative estimates of the breach probabilities of MDLOFs.…”

Section: Introductionmentioning

confidence: 99%

An approach for estimating the breach probabilities of moraine-dammed lakes in the Chinese Himalayas using remote-sensing data

Xian-bin

Liu

Ding

et al. 2012

Nat. Hazards Earth Syst. Sci.

104

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Abstract. To make first-order estimates of the probability of moraine-dammed lake outburst flood (MDLOF) and prioritize the probabilities of breaching posed by potentially dangerous moraine-dammed lakes (PDMDLs) in the Chinese Himalayas, an objective approach is presented. We first select five indicators to identify PDMDLs according to four predesigned criteria. The climatic background was regarded as the climatic precondition of the moraine-dam failure, and under different climatic preconditions, we distinguish the trigger mechanisms of MDLOFs and subdivide them into 17 possible breach modes, with each mode having three or four components; we combined the precondition, modes and components to construct a decision-making tree of moraine-dam failure. Conversion guidelines were established so as to quantify the probabilities of components of a breach mode employing the historic performance method combined with expert knowledge and experience. The region of the Chinese Himalayas was chosen as a study area where there have been frequent MDLOFs in recent decades. The results show that the breaching probabilities (P ) of 142 PDMDLs range from 0.037 to 0.345, and they can be further categorized as 43 lakes with very high breach probabilities (P ≥ 0.24), 47 lakes with high breach probabilities (0.18 ≤ P < 0.24), 24 lakes with mid-level breach probabilities (0.12 ≤ P < 0.18), 24 lakes with low breach probabilities (0.06 ≤ P < 0.12), and four lakes with very low breach probabilities (p < 0.06).

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Section: Introductionmentioning

confidence: 99%

An approach for estimating the breach probabilities of moraine-dammed lakes in the Chinese Himalayas using remote-sensing data

Xian-bin

Liu

Ding

et al. 2012

Nat. Hazards Earth Syst. Sci.

104

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“…The rate of formation of glacial lakes in the Nepal Himalaya has been increasing since the early 1960s (Bolch et al, 2008;Watanabe et al, 2009;Bajracharya and Mool, 2009). Twenty-four new glacial lakes have formed, and 34 major lakes in the Sagarmatha (Mt.…”

Section: Introductionmentioning

confidence: 99%

Changes in Imja Tsho in the Mount Everest region of Nepal

et al. 2014

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Abstract. Imja Tsho, located in the Sagarmatha (Everest) National Park of Nepal, is one of the most studied and rapidly growing lakes in the Himalayan range. Compared with previous studies, the results of our sonar bathymetric survey conducted in September of 2012 suggest that its maximum depth has increased from 90.5 to 116.3 ± 5.2 m since 2002, and that its estimated volume has grown from 35.8 ± 0.7 to 61.7 ± 3.7 million m 3 . Most of the expansion of the lake in recent years has taken place in the glacier terminus-lake interface on the eastern end of the lake, with the glacier receding at about 52 m yr −1 and the lake expanding in area by 0.04 km 2 yr −1 . A ground penetrating radar survey of the Imja-Lhotse Shar glacier just behind the glacier terminus shows that the ice is over 200 m thick in the center of the glacier. The volume of water that could be released from the lake in the event of a breach in the damming moraine on the western end of the lake has increased to 34.1 ± 1.08 million m 3 from the 21 million m 3 estimated in 2002.

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“…In the neighbouring Hinku valley, a GLOF was produced by the failure of the Tam Pokhari (Sabai Tsho) moraine-dammed glacial lake (Osti and Egashira, 2009;Osti et al, 2011). In comparison, extant moraine-dammed glacial lakes in the Khumbu Himal currently include those found in front of Imja Glacier (Watanabe et al, 1994(Watanabe et al, , 2009Reynolds, 2006;Hambrey et al, 2009), Ngozumpa Glacier Thompson et al, 2012) and Lumding Glacier (Bajracharya, 2008).…”

Section: Regional and Global Contextmentioning

confidence: 99%

Reconstructing historic Glacial Lake Outburst Floods through numerical modelling and geomorphological assessment: Extreme events in the Himalaya

Westoby

Glasser

Hambrey

et al. 2014

Earth Surf Processes Landf

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Recession of high-mountain glaciers in response to climatic change frequently results in the development of morainedammed glacial lakes. Moraine dam failure is often accompanied by the release of large volumes of water and sediment, termed a Glacial Lake Outburst Flood (GLOF). Chukhung Glacier is a small (~3 km 2 ) receding valley glacier in Mt. Everest (Sagarmatha) National Park, Nepal. Unlike many Himalayan glaciers, which possess a thick mantle of supraglacial debris, its surface is relatively clean. The glacier terminus has receded 1.3 km from its maximum Holocene position, and in doing so provided the space for an icecontact moraine-dammed lake to develop. The lake had a maximum volume of 5.5 × 10 5 m 3 and drained as a result of breaching of the terminal moraine. An estimated 1.3 × 10 5 m 3 of material was removed from the terminal moraine during breach development. Numerical dam-breach modelling, implemented within a Generalised Likelihood Uncertainty Estimation (GLUE) framework, was used to investigate a range of moraine-dam failure scenarios. Reconstructed outflow peak discharges, including failure via overtopping and piping mechanisms, are in the range 146-2200 m 3 s -1 . Results from two-dimensional hydrodynamic GLOF modelling indicate that maximum local flow depths may have exceeded 9 m, with maximum flow velocities exceeding 20 m s -1 within 700 m of the breach. The floodwaters mobilised a significant amount of material, sourced mostly from the expanding breach, forming a 300 m long and 100 m wide debris fan originating at the breach exit. moraine-dam. These results also suggest that inundation of the entire floodplain may have been achieved within ten minutes of initial breach development, suggesting that debris fan development was rapid. We discuss the key glaciological and geomorphological factors that have determined the evolution of a hazardous moraine-dammed lake complex and the subsequent generation of a GLOF and its geomorphological impact.

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Evaluating the growth characteristics of a glacial lake and its degree of danger of outburst flooding: Imja Glacier, Khumbu Himal, Nepal

Cited by 85 publications

References 31 publications

An approach for estimating the breach probabilities of moraine-dammed lakes in the Chinese Himalayas using remote-sensing data

An approach for estimating the breach probabilities of moraine-dammed lakes in the Chinese Himalayas using remote-sensing data

Changes in Imja Tsho in the Mount Everest region of Nepal

Reconstructing historic Glacial Lake Outburst Floods through numerical modelling and geomorphological assessment: Extreme events in the Himalaya

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