Assessment of glacial lake development and downstream flood impacts of critical glacial lake

Abstract

Glacial lakes are rapidly growing in response to climate change and glacier retreat which may lead to catastrophic socio-economic disasters. The failure of moraine-dammed lakes is associated with hazard for mountain communities due to high velocity and depth with destructive ability of glacial lake outburst floods (GLOFs). Therefore, assessment of glacial lake development and downstream flood impacts of critical glacial lakes with their undesirable outcomes is important. This study presents the insight of glacial lake outburst dynamics using detailed inventory of lakes with hydrological and hydrodynamic modeling over the area to be affected. As a result, total 203 glacial lakes are found having surface area > 0.01 km2 and more than 90% glacial lakes are situated at the high elevation (> 4500 m) zone. In addition, increasing lake size could increase the frequency of outburst and cause socio-economic damages. During the outburst of GL-3 Lake, the flow discharge could be increased by 4–6 times with 100% increase in velocity and depth and the travel time is 1.5–2.5 h to reach the Chugthang habitat. This increasing water level will directly affect the hydropower project at Chugthang, as there is no flat terrain for water spread. The flooding contributed due to lack of awareness of GLOF hazard and non-existence of land-use planning. Therefore, this study anticipated supporting the decision-makers to prepare the management plan in response to futuristic climate scenario and risk measures with inclusive of GLOFs; also suggested to utilize the glacial lakes as reservoir to reduce the risk for mountain communities. © 2021, The Author(s), under exclusive licence to Springer Nature B.V.