India: Indicating the impact of global warming, glacier melting over a 47-year period has led to formation of seven new glacial lakes in Chandra-Bagha Basin of western Himalayas.
Preliminary findings of an ongoing study by researchers from IIT, Bombay, showed that glacier lakes underwent continuous changes between 1963 and 2010. GIS tools and high resolution remote sensing technology were used to delineate glacier lakes situated in inaccessible Himalayan terrain. In all, 15 large glacier lakes situated at an elevation between 4069 meters to 5252 meters were chosen for monitoring the changes that occurred.
Continuous ice-melting due to glacier recession (loss of ice due to excess melting) caused the formation of seven new lakes near the mouth of the glaciers. These were formed as moraine-dammed lakes and the glacier-lake area was estimated to have increased approximately by 2591 sq.meters during the 47-year period. Moraine is a depositional feature of glacier. As the glacier starts moving, it accumulates small rocks, debris, ice fragments and soil.
There was no significant change in the area of eight other glacier lakes which were situated at a higher altitude and not created by melting. According to Farjana Sikandar Birajdar, lead author of the study, the melting of glaciers would reduce the ice mass balance even as it resulted in formation of new lakes with loose moraine. This in turn could lead to a sudden breach of the unstable moraine dams and the phenomenon of glacial lake outburst floods (GLOF), posing a serious hazard to settlements downstream. She said many previous studies in the Himayalan region revealed that the rate of melting was increasing. If the same trend continued, glaciers would vanish in the long-term, adversely impacting the storage of freshwater resources as also hydro-power generation.
In a bid to overcome any future problem, she suggested that foundations of such moraine-dammed lakes should be strengthened. Besides by studying the rate of glacier melting, it could be predicted when a lake would burst and the people living downstream could be forewarned, she added.
Source: The Hindu