Glacial lakes multiply in Himachal Pradesh and Tibet, poses threat to lives and infra downstream

Sub: Geo

Sec: Indian Physical Geography

Context:

Moraine-dammed lakes on the rise in Himachal Pradesh and Trans Himalayan Region of Tibet.
There were 1,048 glacial lakes in the Sutlej catchment area in 2023, up from 562 in 2019, satellite data shows.

Study and findings:

The number of glacial lakes in the Sutlej 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 Sutlej 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: 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.
The swift melting of glaciers and less snowfall during the winter could be reasons behind the rise in lakes
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
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 downstream.

Glacial Lakes

Glacial lakes are formed when a glacier erodes the land and then melts, filling the depression created by the glacier.
Glacial lakes are classified into four main types based on their formation process: Moraine-dammed, Ice-dammed, Erosion, and other glacial lakes.

Moraine-dammed lakes

A moraine-dammed lake occurs when the terminal moraine has prevented some meltwater from leaving the valley.
When a glacier retreats, there is a space left over between the retreating glacier and the piece that stayed intact which holds leftover debris (moraine).
Meltwater from both glaciers seep into this space creating a ribbon-shaped lake due to the pattern of ice melt.