An overview of glacial hazards in the Himalayas

Glaciers and snowfields call form potential hazards in the Himalayas, and i n similarly glacierised regions of the world. Some glaciological phenomena can have significant impacts upon society over a short time scale (minutes- days), such as ice/snow avalanches and glacial floods. Other related hazard s call be equally serious but less obvious when considered on a much longer time scale (months-years-decades), such as glacier volume fluctuations lea ding to water resource problems. Only when humans and their activities beco me vulnerable to glacier-related processes is there considered to be a haza rd risk. As glaciers recede in response to climatic warming, the number and volume o f potentially hazardous moraine-dammed lakes in the Himalayas is increasing . These lakes develop behind unstable ice-cored moraines: and have the pote ntial to burst catastrophically, producing devastating Glacial Lake Outburs t Floods (GLOFs). Discharge rates of 30,000 m(3) s(-1) and run-out distance s in excess of 200 km have been recorded. Despite the scale of the risk, it is possible to assess and mitigate hazardous lakes successfully. Hazard as sessment using satellite images has br:en effective for remote areas of Bhu tan, and remediation techniques successfully developed in the Peruvian Ande s are now being deployed for the first time in Nepal. (C) 2000 Elsevier Sci ence Ltd and INQUA. All rights reserved.