Evaluation of Glacial Lake Outburst Flood Susceptibility Using Multi-Criteria Assessment Framework in Mahalangur Himalaya

Abstract

Ongoing recession of glaciers in the Himalaya in response to global climate change has far-reaching impacts on the formation and expansion of glacial lakes. The subsequent glacial lake outburst floods (GLOFs) are a significant threat to lives and livelihoods as they can cause catastrophic damage up to hundreds of kilometres downstream. Previous studies have reported the rapid expansion of glacial lakes and several notable destructive past GLOF events in the Mahalangur Himalaya, suggesting a necessity of timely and updated GLOF susceptibility assessment. Here, an updated inventory of glacial lakes across the Mahalangur Himalaya is developed based on 10-m Sentinel-2 satellite data from 2018. Additionally, the GLOF susceptibilities of glacial lakes (≥0.045 km2) are evaluated using a multi-criteria-based assessment framework where six key factors are selected and analyzed. Weight for each factor was assigned from the analytical hierarchy process. Glacial lakes are classified into very low, low, medium, high, and very high GLOF susceptibility classes depending upon their susceptibility index based on analysis of three historical GLOF events in the study area. The result shows the existence of 345 glacial lakes (>0.001 km2) with a total area of 18.80 ± 1.35 km2 across the region in 2018. Furthermore, out of the 64 glacial lakes (≥0.045 km2) assessed, seven were identified with very high GLOF susceptibility. We underline that pronounced glacier-lake interaction will likely increase the GLOF susceptibility. Regular monitoring and more detailed fieldworks for these highly susceptible glacial lakes are necessary. This will benefit in early warning and disaster risk reduction of downstream communities.

Controls of outbursts of moraine-dammed lakes in the greater Himalayan region

“…Our model results quantitatively support qualitative notions of several basin-wide studies in the HKKHN (e.g. Ives et al, 2010;Khadka et al, 2021;Prakash and Nagarajan, 2017) and elsewhere (McKillop and Clague, 2007), which proposed that larger moraine-dammed lakes have a higher potential for releasing GLOFs.…”

“…Following the outlines of glacier regions in High Mountain Asia used in the Randolph Glacier Inventory version 6.0 (RGI Consortium, 2017) and those defined by Brun et al (2017 subdivided our study area into seven mountain ranges: the Hindu Kush, the Karakoram, the Western Himalaya, the Central Himalaya, the Eastern Himalaya, the Nyainqentanglha, and the Hengduan Shan. Meltwater from the HKKHN's extensive snow and ice cover, often referred to as the "Third Pole", feeds 10 major river systems to provide water for some 1.3 billion people (Molden et al, Mergili and Schneider (2011) Catchment area Allen et al (2019); GAPHAZ (2017) Glacial lake area Aggarwal et al (2016); Allen et al (2019); Bolch et al (2011); GAPHAZ (2017); Ives et al (2010); Khadka et al (2021); Mergili and Schneider (2011); Prakash and Nagarajan (2017); Wang et al (2012); Worni et al (2013) Lake-area change (growth and shrinkage, absolute change) Summer precipitation or proxy of monsoonality Wang et al (2008Wang et al ( , 2012 Figure 1. Overview map of the HKKHN showing the distribution of moraine-dammed lakes in 1 • × 1 • bins (blue bubbles scaled by area), their elevation (expressed as quantiles coded by arrows; see inset for elevation distribution), and average monsoonality (colour coded; see inset for monsoonality distribution), defined here as the fraction of total annual precipitation falling in the summer months.…”

“…et al (2016);Bolch et al (2011);Ives et al (2010);Khadka et al (2021);Mergili and Schneider (2011);Prakash and Nagarajan (2017); Rounce et al . (2019); Bolch et al (2011); Dubey and Goyal (2020); GAPHAZ (2017); Ives et al (2010); Khadka et al (2021); Prakash and Nagarajan (2017); Rounce et al (2016); Wang et al (2011); Worni et al (2013) Width-to-height ratio -Aggarwal et al (2016); Bolch et al (2011); GAPHAZ (2017); Ives et al (2010); Prakash and Nagarajan (2017); Worni et al (2013) Lake freeboard -Bolch et al (2011); GAPHAZ (2017); Kougkoulos et al (2018); Mergili and Schneider (2011); Prakash and Nagarajan (2017); Worni et al (2013) Existence of a buried ice core -Bolch et al (2011); Dubey and Goyal (2020); GAPHAZ (2017); Ives et al (2010); Rounce et al (2016) Dam type GAPHAZ (2017); Kougkoulos et al (2018); Mergili and Schneider (2011); Wang et al (2011); Worni et al .…”

Glacial Lake Area Change and Potential Outburst Flood Hazard Assessment in the Bhutan Himalaya

“…The distance and slope between the lake and the mother glacier determine the lake-glacier interaction (Wang, 2011). GLOFs in the Himalayas (Khadka et al, 2021) and on the Tibetan Plateau (Wang et al, 2011) have been within 0-700 and 0-800 m lake-glacier distance, respectively. In the Bhutan Himalaya, out of 13 identifiable lakes with a GLOF history, at least two lakes have a lake-glacier distance of 1,000 m. Therefore, here, we used a maximum threshold lakeglacier distance of 1,000 m. This is also the value used by Allen et al (2019) for the region-wide hazard assessment of lakes in the Tibetan Plateau.…”

Glacial lake outburst floods enhance benthic microbial productivity in perennially ice-covered Lake Untersee (East Antarctica)

“…GLOFs are typically reported from Iceland and Greenland, where the high discharge (mega-GLOF > 10 6 m 3 ) causes substantial damage to infrastructure and nearby communities 9 . Smaller magnitude GLOFs are also often reported from the Himalayas 10,11 and Andean Patagonian lakes and fjord 12,13 . However, GLOFs in Antarctica have been rarely reported.…”