On the formation of supraglacial lakes on debris- covered glaciers

Abstract

Analyses of satellite imagery obtained in 1989-1990 and topographic maps from 1966 have been undertaken for the glacierized areas of Bhutan. It has been found that where supraglacial lakes have formed since 1966, surface gradients of the glaciers concerned were in all cases less than 2°. At gradients of 2-10° supraglacial ponds can form but tend to be transient due to the opening and closing of crevasses. By identifying the conditions under which large supraglacial lakes form it is possible to use these criteria to predict where such lakes may develop in the future. This will allow suitable monitoring programmes to be introduced and, where necessary, suitable engineering remediation works to be undertaken in order to prevent the collection of large volumes of water that may be liable to form glacier lake outburst floods in the future.