Modeling Potential Glacial Lake Outburst Flood Process Chains and Effects From Artificial Lake-Level Lowering at Gepang Gath Lake, Indian Himalaya

Sattar, A and Allen, S and Mergili, M and Haeberli, W and Frey, H and Kulkarni, AV and Haritashya, UK and Huggel, C and Goswami, A and Ramsankaran, RAAJ (2023) Modeling Potential Glacial Lake Outburst Flood Process Chains and Effects From Artificial Lake-Level Lowering at Gepang Gath Lake, Indian Himalaya. In: Journal of Geophysical Research: Earth Surface, 128 (3).

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Abstract

Glacial lake outburst floods (GLOFs) are a severe threat to communities in the Himalayas; however, GLOF mitigation strategies have been implemented for only a few lakes, and future changes in hazard are rarely considered. Here, we present a comprehensive assessment of current and future GLOF hazard for Gepang Gath Lake, Western Himalaya, considering rock and/or ice avalanches cascading into the lake. We consider ground surface temperature and topography to define avalanche source zones located in areas of potentially degrading permafrost. GLOF process chains in current and future scenarios, also considering engineered lake lowering of 10 and 30 m, were evaluated. Here, varied avalanche impact waves, erosion patterns, debris flow hydraulics, and GLOF impacts at Sissu village, under 18 different scenarios were assessed. Authors demonstrated that a larger future lake does not necessarily produce larger GLOF events in Sissu, depending, among other factors, on the location from where the triggering avalanche initiates and strikes the lake. For the largest scenarios, 10 m of lowering reduces the high-intensity zone by 54 and 63 for the current and future scenarios, respectively, but has little effect on the medium-intensity flood zone. Even with 30 m of lake lowering, the Sissu helipad falls in the high-intensity zone under all moderate-to-large scenarios, with severe implications for evacuations and other emergency response actions. The approach can be extended to other glacial lakes to demonstrate the efficiency of lake lowering as an option for GLOF mitigation and enable a robust GLOF hazard and risk assessment. © 2023. The Authors.

Item Type:	Journal Article
Publication:	Journal of Geophysical Research: Earth Surface
Publisher:	John Wiley and Sons Inc
Additional Information:	The copyright for this article belongs to John Wiley and Sons Inc.
Keywords:	glacial lake outburst floods; GLOF exposure; GLOF mitigation; GLOF modeling; GLOF risk reduction; lake lowering; western Himalaya
Department/Centre:	Division of Mechanical Sciences > Divecha Centre for Climate Change
Date Deposited:	21 Apr 2023 09:45
Last Modified:	21 Apr 2023 09:45
URI:	https://eprints.iisc.ac.in/id/eprint/81323

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