Fears of glacial lake outburst floods allayed
[KATHMANDU] The International Centre for Integrated Mountain Development (ICIMOD) has good news for people living in the Nepal Himalayas – its latest survey shows three lakes formed by melting glaciers are not about to burst as previously feared.
In 2009, ICIMOD studied 1,466 glacial lakes in Nepal, in collaboration with the World Bank and non-government organisations (NGOs). Its teams identified six of them as candidates for glacial lake outburst floods (GLOFS).
Extensive field studies on three of these – Imja, Thulagi and Tsho Rolpa – in 2009 found that none of them posed an immediate risk of GLOF, unless external factors such as an earthquake or sudden sharp rise in temperature were to occur.
The findings are in contrast to a previous 2007 ICIMOD report ‘Impact of Climate Change on Himalayan Glaciers and Glacial Lakes: Case Studies on GLOF and Associated Hazards in Nepal and Bhutan’ in which Imja was identified as a ‘‘potentially dangerous’’ lake, where mitigation measures are ‘‘urgent’’.
The reduced threat is due to several features, including the lakes’ stable ‘end-moraine complexes’ — dams that hold water in place — and free-flowing water outlets that reduce pressure on the lakes.
The findings were made public in a series of community discussions, the first of which was held on 22 February.
From 2000 onwards, the general trend of glacial melt in the region has decreased, the latest analysis showed.
But the ICIMOD team also advised regular monitoring of the lakes. Glacial lakes often provide new sources of water, hydroelectricity and tourism, but in the case of a dam breach they release high-velocity floods that can damage life and property downstream.
ICIMOD organised workshops in three towns in northern Nepal, which are downstream of the lakes studied, to share knowledge, discuss implications and gather feedback on how to respond to potential hazards.