With glacier sizes rapidly reducing due to the impact of climate change in recent years, there has been a gradual rise of moraine-dammed lakes in Himachal Pradesh and the Trans Himalayan Region of Tibet, posing a potential threat to human life and infrastructure further downstream.
The number of glacial lakes in the Satluj river catchment area has almost doubled from 562 in 2019 to 1,048 in 2023, according to satellite data analysed in a recent study by the Centre on Climate Change of Himachal Pradesh Council for Science Technology-Environment (HIMCOSTE). The catchment area of the Satluj basin was studied from upstream of Jhakri to the Mansarover Lake in Tibet, in the Trans Himalayan Region from where the river originates.
Smaller lakes sprout up
Of the 1,048 lakes mapped in 2023, 900 are small, each spanning an area of less than five hectares, while 89 lakes have an area between 5 hectares and ten hectares, and 59 lakes are bigger than 10 hectares each.
“Over the years, the number of glacial lakes has been gradually increasing. In fact, as the frequency of small lakes with an area of less than five hectares has been rising, it indicates that the climate warming effects are more significant in the higher Himalayan region. The swift melting of glaciers and less snowfall during the winter could be reasons behind the rise in lakes,” said S.S. Randhawa, a co-author of the study, and the principal scientific officer at HIMCOSTE.
He said it could be inferred from the basin-wise analysis that the number of lakes is much higher in the Tibetan Himalayan Region or the Upper Satluj basin, in comparison to the Spiti and Lower Satluj basins, indicating that the Upper Satluj basin is more susceptible to glacial lake formations. “As the formation of small lakes is relatively higher in the upper region, it indicates greater climate change impact in the higher region in comparison to the lower regions. The average temperature in the high altitudes areas is rising faster than the lower areas,” Mr. Randhawa said.
Downstream danger
The study, which analysed multi-spectral satellite images, suggests that the rise in glacial lakes in Himachal Pradesh’s river basins can be disastrous downstream if the lakes burst their bounds for any reason.
“Climate change has influenced the health of glaciers in the entire Himalayan region. As a result, the cryospheric cover over the Himalayan terrain is reducing. One of the ramifications of this is the development of high-altitude glacial lakes,” said Sunil Dhar, Dean of the Department of Environmental Sciences at the Central University of Jammu. “The number of such lakes has increased over the years and these lakes have become unstable due to the increase in the volume of water or due to the calving effect of adjoining glaciers, [creating] avalanche either of snow or rocks. These lakes have a potential of bursting out, and depending on the volume of water, velocity and the outburst spread, it can pose a threat to habitations and infrastructure in the down stream region,” he added.
Published - August 10, 2024 09:59 pm IST
