Alarming rise in glacial lakes in Satluj basin in five years: Study

Pratibha Chauhan
Tribune News Service
Shimla, August 1
With the increase in number of glacial lakes in the Satluj basin from 562 in 2019 to 1,048 in 2023, the potential threat of destruction in case of lake bursting, triggered by an avalanche or a landslide remains high.
A study of the Satluj basin undertake by the Centre for Climate Change in the Council for Science, Environment and Technology, has indicated that out of the total 1,048 lakes mapped in 2023, as many as 900 lakes have been mapped as the small one with area less 5 hectares, 89 lakes with area 5-10 hectares and 59 lakes with area more than 10 hectares. The study based on satellite imagery was undertaken in the entire Satluj basin from April to November 2023 with some mega hydel projects being located on the Satluj river.

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Climate-induced changes

• Declining snowfall
• Drying up of perennial streams
• Temperate belt has shifted upward
• Productivity of apple has been adversely affected
• Rabi season has shifted and shortened
• The incidences of diseases and pests have become more severe

“The magnitude of such lakes as far as the destruction is concerned cannot be overruled. Hence, all such lakes with area more than 10 hectare and the area between 5 and 10 hectare can be vulnerable considering the present trends in the climate science and the climate induced hazards threat,” said Dr SS Randhawa, Principal Scientific Officer in the Council, who conducted the study.
The Kinnuar district administration is closely monitoring the Kashang glacier in Kinnaur. A disaster management team was sent to the site on Tuesday to assess the potential threat. There have been several instances of cloud bursts and floods, especially in Kullu district.
The number of glacial lakes in the Satluj basin has increased from 562 in 2019, 993 in 2020, 880 in 2021, 995 in 2022 and 1,048 in 2023. The number of lakes delineated is much higher in the Tibetan Himalayan Region falling in Upper Satluj basin in comparison to basins of Spiti and Lower Satluj, making Upper Satluj basin more susceptible for the glacial lake formation.
The increase in the number of small lakes further indicates that the rising temperature which is comparatively more in the higher regions than the lower regions and has adversely affected the Himalayan glaciers.
In this study, a total of 197 lakes, which were identified earlier by the National Remote Sensing Agency, Hyderabad, were considered as the base line data for the year 2007 and since 2009 the State Council for Science Technology and Environment has been monitoring all such lakes in the entire Satluj catchment.
The main threat from the Parechu lakein Tibet is being monitored regularly. Himachal Pradesh invariably experiences flashfloods and in 2000, the Satluj valley suffered damages of more than Rs 800 crore.