A Himalayan threat, glacial lakes growing

Marked increase in water bodies over a year

Pratibha Chauhan

Tribune News Service

Shimla, December 30

The adverse impact of climate change in the higher Himalayan region has resulted in considerable increase in the number of glacial lakes within a short span of one year, which could pose a major threat to downstream villages if they swell up and burst.

The latest study undertaken by the State Centre on Climate Change under the aegis of Council for Science, Technology and Environment has indicated that there has been a considerable increase in the number of glacial lakes up to five hectares in various river basins in the Upper Himalayas. The study by Dr SS Randhawa is based on the comparison of satellite images of 2017 and 2018.

The Satluj basin has seen the highest increase — 127 lakes, including 49 with an area of more than 10 hectares —- followed by 34 lakes in the Chenab basin and 12 in the Ravi basin. It is only in the Beas basin that the number of lakes has gone down from 101 to 65. The increase in the Satluj basin has been 16 per cent within a year.

The 2013 tragedy in Uttarakhand has also been correlated with the bursting of an 8-hectare lake in front of the snout of the Chorabari glacier that caused widespread damage in the downstream areas during heavy rain. The findings also assume significance in view of a major threat that had been caused due to the creation of the huge Parechu lake in Tibet in 2004, following which it is being monitored by various agencies to avert any major loss to life and property in case it bursts.

The comparative analysis of a total number of lakes formed in each basin between 2018 and 2015 reveals an increase of 97 per cent in the Satluj basin (379 lakes), followed by the Chenab basin seeing 32 per cent rise (62 lakes), and the Ravi basin showing 94 per cent increase (32 lakes). In the case of the Beas basin there has been a decrease of about 36 per cent (38 lakes).

“In view of these findings it becomes imminent to have regular monitoring of the upper catchment areas to avert a major catastrophe in case of lake bursting,” asserts DC Rana, Director, Department of Environment, Science and Technology. Many such incidents have taken place in Nepal though there are no reports of such incidents in the Indian Himalayas.

Threat of bursting

*Most glacial lakes are formed by the accumulation of vast amounts of water from the melting of snow and by blockade of end moraines in the valleys close to the glaciers.

*The lakes can also be formed due to landslides causing artificial blocks in waterways. The break of a moraine/block may release water from these lakes, causing flash floods.

BOX: Lakes in River Basins

Basin 2017 2018

Satluj 642 769

Chenab 220 254

Ravi 54 66

Beas 101 65