Publication Name

Glacial lakes and GLOFs

CASE STUDY

lakes in Nepal is 1,466 covering an area of 64.75 km 2 . Of these lakes, 21 are potentially dangerous and 6 are defined as high priority lakes requiring extensive field investigation and mapping. 56 Thirty-five GLOFs (5 in Bhutan including the Lemthang Tsho GLOF of June 2015, 16 in China and 14 in Nepal) have been reported in the Hindu Kush Himalayan region. 57 Another study reported 21 GLOF events (17 before 1970 and 4 from the 1970s to 2010) in the Tibetan branch of the Kuri Chu and the Chamkhar Chu, Pho Chu and Mo Chu rivers. 58 These GLOFs resulted in significant damage to people, crops, infrastructure and hydropower plants. Thus, GLOF risk assessment has become an issue of considerable significance that must be dealt with urgently.

as a glacial lake outburst flood (GLOF), which can cause extensive damage to lives, livelihoods and infrastructure downstream. With climate change accelerating there is a growing concern that the frequency of GLOFs could increase in the future. A comprehensive inventory of glaciers, glacial lakes and potentially dangerous glacial lakes was compiled in the late 1990s and early 2000. This inventory identified a total of 8,790 glacier lakes in Bhutan, India, Pakistan, Nepal and the Ganges basin in China. Of these, 204 were listed as potentially dangerous glacial lakes. 55 ICIMOD updated the inventory of glacial lakes in Nepal and assessed their GLOF risk based on satellite images from 2000/2001. The updated number of glacial

All lakes formed by present or past glacier activity are described as glacier (glacial) lakes. A glacial lake can form on the surface of the glacier (supra-glacial), within the glacier ice (englacial), below the glacier ice (subglacial), in front of the glacier (proglacial), at the side/surrounding the glacier (periglacial) or in relict cirques (a steep bowl-shaped depression occurring at the upper end of a mountain valley). The impact of climate change on Himalayan glaciers is becoming apparent with the majority of glaciers shrinking. The formation and growth of glacial lakes is a phenomenon directly related to glacier shrinking. The majority of glaciers are dammed by unstable moraines and have the potential to breach due to internal or external triggers. Once the moraine is breached it can cause a large flash flood known

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