A glacial lake outburst flood (GLOF) is a sudden release of water from a lake fed by glacier melt that has formed at the side/in front of/ within/ beneath or on the surface of a glacier. The lake, bound only by loose soil and debris called moraine, could cause catastrophic flooding downstream due to breaching, slope failure, overtopping or other failure mechanisms. This can have major geomorphic and socio-economic impacts.
Glaciers across the world such as ones in the Hindu-Kush, Karakoram, and Himalayas are shrinking rapidly, forming glacial lakes and causing potentially catastrophic floods. There are various reasons behind the increasing frequency of GLOF such as:
·The impact of global warming and consequent climate variability has led to melting of various glaciers in a short period of time. This has led to the formation of number of glacial lakes which are inherently unstable. Also, this has led to expansion of already existing
lakes and merging of nearby lakes, making them more prone to flooding.
·The instability of the glacial lakes is compounded by increase in debris cover and accumulation of black carbon (soot) in the areas of the glaciers.
·Further measures can be taken like GLOF hazard mapping, vulnerability assessment, hazard zone demarcation, and identification of GLOF safe evacuation sites
Considering the increasing vulnerability of Himalayan region, recently, the Centre for Development of Advance Computing (C-DAC) has developed an early warning GLOF system for the Sikkim government.
