Glacial lakes in the Indian Himalayas — From an area-wide glacial lake inventory to on-site and modeling based risk assessment of critical glacial lakes

Glacial lake outburst flood risk in Himachal Pradesh, India: an integrative and anticipatory approach considering current and future threats

“…Changes in both the climate system (left) and socio-economic processes (right) are drivers of hazards, exposure, and vulnerability, which in turn contribute to GLOF risk (modified from IPCC 2014) approaches. Ives et al (2010) included 156 lakes within their lake inventory for Himachal Pradesh, while Worni et al (2013) recorded only 45 lakes focusing on water bodies larger than 0.01 km 2 . The most comprehensive lake inventory comes from the state government authorities, who report nearly 600 mapped lakes as of 2013 formed within the four main hydrological basins of Himachal Pradesh (HPCCC 2014).…”

“…The inclusion of a shadow mask and image filtering (majority filter relative to 4 neighbouring pixels) reduced misclassifications and removed isolated pixels, with results validated against the manually constructed lake inventory from the state government. The final selection of glacial lakes considered only those lakes with an area [0.01 km 2 (after McKillop and Clague 2007;Worni et al 2013), located above 3500 m, and either dammed or fed directly by glacial processes. This final step remains somewhat subjective, but recognises that moraine-dammed lakes may be positioned well beyond the current terminus position of fast retreating glaciers.…”

“…Here, many glacial lakes are evident, and a high proportion of these lakes are surrounded by steep high-mountain flanks, giving rise to large impact predisposition areas from which mass movements of ice and rock may trigger outburst floods. The two lakes identified as having the highest potential for impacts from rock and ice were similarly assessed as 'critical' in the earlier study of Worni et al (2013), where experts assessed a smaller number of lakes using high-resolution imagery. Focussing on the central District of Kullu, far-reaching GLOF events are evident, with many paths converging within the Beas valley to result in a notable area of high hazard in the adjacent downstream District of Mandi, Tehsil of Aut (A).…”

“…ICIMOD 2011; Wang et al 2011;Worni et al 2013), assessment schemes are heterogeneous and typically still require subjective case-by-case classification of potential triggering threats such as impacts from ice or rock avalanches. Furthermore, the crucial socioeconomic factors that determine the vulnerability of a given region to outburst flood events (Hegglin and Huggel 2008;Carey et al 2012) have been rarely integrated within largescale assessment schemes (Wang et al 2015).…”

Identification of Potential Glacial Lake Sites and Mapping Maximum Extent of Existing Glacier Lakes in Drang Drung and Samudra Tapu Glaciers, Indian Himalaya

“…One of these inventories suggests the presence of 251 glacial lakes (>0.01 sq. km) of which 105 present GLOF risk, 12 of them being critical [9][10][11] . However, there have been no studies to predict the maximum possible expansion of the existing lakes, which is crucial because lake volume determines the peak discharge and hence the severity of GLOF 12 .…”