ASM
Himalayan Floods from Glacial Lakes
A new study is advocating the development of an early warning system for glacial lake outburst flooding in the Himalayas.
The study was supported by the UN's Environment Program Regional Office for Asia and the Pacific. Its authors are Samjwal Ratna Bajracharya, Pradeep Kumar Mool, and Basanta Raj Shrestha from the International Centre for Integrated Mountain Development in Kathmandu.
In the face of global warming, most Himalayan glaciers have been retreating; some at a few metres per annum, and some at tens of metres. This has resulted in an increase in the number, and size, of the lakes at the ends of the glaciers.
About 15,000 glaciers and 9000 glacial lakes are known in Bhutan, Nepal and Pakistan, and in China and India.
In Nepal alone, twenty one of these lakes have burst their banks in the past few years, releasing catastrophic floods down the river valleys. Another 200 are believed to be dangerous.
A remarkable example is Lake Imja Tsho in the Dudh Koshi sub-basin (Khumbu-Everest region). It was virtually non-existent in 1960. It now covers nearly a square kilometre. The Imja glacier, which feeds it, is retreating at an unprecedented 74 metres per year (between 2001 and 2006).
The authors of the report say it underlines the urgent need to enhance scientific knowledge of glacier environments. It is essential to monitor glaciers and glacial lakes continuously, in order to carry out vulnerability assessments, and to implement mitigation and adaptation mechanisms.
Regional co-operation is also required, to develop a co-ordinated strategy to deal with trans-boundary issues related to the impacts of climate change.
Visit http://books.icimod.org/index.php/search/publication/169 to download the report.
