GLOF Risk Reduction Activities in Nepal-ICIMOD - 2011

Abstract: The global temperature rise has made a tremendous impact on the high mountainous glacial environment. In the last century, the global average temperature has increased by approximately 0.75 °C and in the last three decades, the temperature in the Nepal Himalayas has increased by 0.15 to 0.6 °C per decade. From early 1970 to 2000, about 6% of the glacier area in the Tamor and Dudh Koshi sub-basins of eastern Nepal has decreased. The shrinking and retreating of the Himalayan glaciers along with the lowering of glacier surfaces became visible after early 1970 and increased rapidly after 2000. This coincides with the formation and expansion of many moraine-dammed glacial lakes, leading to the stage of glacial lake outburst flood (GLOF). The past records show that at least one catastrophic GLOF event had occurred at an interval of three to 10 years in the Himalayan region. Nepal had already experienced 22 catastrophic GLOFs including 10 GLOFs in Tibet/China that also affected Nepal. The GLOF not only brings casualties, it also damages settlements, roads, farmlands, forests, bridges and hydro-powers. The settlements that were not damaged during the GLOF are now exposed to active landslides and erosions scars  making them high-risk areas.

The glacial lakes are situated at high altitudes of rugged terrain in harsh climatic conditions. To carry out the mitigation work on one lake costs more than three million US dollars. In Nepal, 18 lakes were already identified as potentially dangerous and more than 70 lakes are growing in size, which might be dangerous in the future. Hence to carry out the physical mitigation works on these lakes are impractical, but creating awareness and bringing adaptation measures can effectively reduce the GLOF risk.

Glacial lake outburst floods risk reduction activities in Nepal
Samjwal Ratna BAJRACHARYA
sabajracharya@icimod.org
International Centre for Integrated Mountain Development (ICIMOD)
PO Box 3226 Kathmandu Nepal