Most of Sutlej basin glaciers will disappear by 2090: Study

This calls for better dam management practices to prevent excess water from flooding habitations downstream of the river. 
Representational Image.
Representational Image.

BENGALURU: Climate change and global warming presents a scary scenario for India with 2,026 glaciers in the Sutlej river basin in the Himalayas set to lose up to 81% of the area and many of them completely vanishing by the year 2090. This threatens the sustenance of lakhs of people among the mountainous communities due to flash floods from glacial lake water bursts when rain and glacier ice melt to fill up spaces once occupied by the glaciers.

This worrisome projection is based on detailed research done in the background of increased emission of greenhouse gases by Bengaluru-based Divecha Centre for Climate Change, Indian Institute of Science. The research paper will be published in the May 25 issue of the journal Current Science, under the title ‘Large losses in glacier area and water availability by the end of the 21st century under high emission scenario, Sutlej basin, Himalaya’.

Employing two sophisticated climate projection models to assess the impact of rain and temperatures on the Sutlej basin glaciers in the 106-year period between 1984 and 2090, the researchers said projections of one of the models (CNRM-CM5) indicated that by the year 2050, the Sutlej basin will experience an increase in summer temperature by 1.48 degrees Celsius and an 8% decrease in winter snowfall with 2010 as the average year baseline. The same model predicts that by 2090, there will be an increase of 3.5 degrees Celsius in summer temperature and 24 per cent increase in the winter rain.

Projections using another climate model (GFDL-CM3), while comparing with climate data of 2005-2015, showed a rise in summer temperature by 3.7 degrees Celsius by 2050 and by 7.94 degrees Celsius by 2090.

The researchers said the vanishing Sutlej river basin glaciers will result in an initial increase in volumes of water to the Gobind Sagar reservoir formed by the Bhakra Dam along the Sutlej river in Bilaspur, Himachal Pradesh. This calls for better dam management practices to prevent excess water from flooding habitations downstream of the river. 

“At present, the total run-off water from Sutlej basin to Bhakra dam is 14 cubic km. According to our model results, in 2010, the Bhakra reservoir (Gobind Sagar) received 2 cubic km of water from glaciated terrain which accounts for about 14% of the total run-off,” the paper said.

“Due to the rapid melting of glaciers in Sutlej basin, the run-off will reach a maximum of 2.2 cubic km per year by 2050 and then reduce to 1.49 cubic km per year by the end of the century due to glacier retreat,” the paper says. The research shows that the total volume of water stored in the glaciers is in the range of 57 cubic km to 81 cubic km.

They found that 56% of the total volume (37.6 cubic km) of water was stored in larger glaciers occupying more than 5 sqkm area each and totally covering 517 sqkm. At least 95% of the 2,026 glaciers researched contained less than 0.1 gigaton of ice (1 gigaton = 1 billion metric tons).

Dr Anil V Kulkarni, Distinguished Scientist, DCCC, senior glaciologist and corresponding author for the paper, told The New Indian Express, “The loss in glacier mass and area will affect the contribution of water run-off to Bhakra reservoir. Besides, the glacial area will receive rain even under a high emission scenario.

However, the disappearance of smaller glaciers located at lower elevation will change the pattern and overall availability of water to various hydro-power projects in the downstream areas of the basin, thereby posing new challenges for the communities in the Himalayan region.”

He explained that this will increase the occurrence of disastrous events such as glacier lake outburst floods. When glaciers melt, they leave behind huge depressions which are filled by water from rain and glacial melt. This can cause breaches, causing flash floods as in June 2013 in Uttarakhand which destroyed entire villages and settlements, killing about 6,000 people.

“Therefore, this calls for extensive investigation and improvement in existing water management practices in the Sutlej basin,” he said. The study was conducted by six researchers, including Dr Kulkarni, from DCCC, one from IISc’s Centre for Atmospheric & Oceanic Sciences, and two from British Antarctic Survey, Cambridge, the UK.

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