Surprising Revelations Through ISRO Satellite - Size Of Twenty-Seven Percent Of Identified Glacial Lakes Have Increased,130 Of These Exist In Bharat

Hello, Everyone!

Due to many climate changes following adverse effects of global warming afforestation, pollution, and, increasing population, our glaciers are retreating and thinning every year leading to the creation of new glacial lakes and an increased size of the already existing lakes. This is a concern prevalent in glacial regions.

According to ISRO; the images outlined by the Satellite monitoring done over the watersheds {bodies that collect water and from where the water gets into the mainstream river, it acts like a natural basin such as ridges or hills which is bounded with geographical divides}of our country's river basins in the Himalayan areas, there have been considerable changes in the river basins from 1984 to 2023.

According to ISRO; the images outlined by the Satellite monitoring done over the watersheds {bodies that collect water and from where the water gets into the mainstream river, it acts like a natural basin such as ridges or hills which is bounded with geographical divides}of our country's river basins in the Himalayan areas, there have been considerable changes in the river basins from 1984 to 2023.

Pic Source :The Tribune

There has also been a bit concerning revelation that; from the 2,431 observed from 2016 to 2017 they had a size of more than 10 hectares, and 676 glacial lakes have increased in size by the year 1984.

According to a statement by our country's space agency ISRO, there has been an increase in the size of 27 percent of the glacial lakes situated in the Himalayas.

But what are glacial lakes? These are water bodies created due to glacial phenomena mainly associated with the existence and recession of glaciers. They are formed due to many glacial phenomena such as glacial erosion, Glacial deposition, Moraine formation, Iceberg breaking into chunks of ice in the water bodies {called iceberg calving} and lastly melting of glacial ice. These lakes can be diverse in their looks, size, and deepness and play a vital role in the people habituating in the downstream regions and the ecosystem.

According to ISRO; from 676 lakes, 601 lakes have incresed twice in size; however, 10 lakes have extended from 1.5 to 2 folds and sixty-five lakes have extended in size 1.5 folds. In line with the previously mentioned statement by ISRO, there has been other information outlined by our country's space agency that 130 of the 676 glacial lakes are based in India with 65 situated in the Indus basin and 7 located in the Ganga basin and 48 glacial lakes are situated in the Brahmaputra river basin.

As per the height-based observation of these glacial lakes; the 314 lakes are perched at the height of 4000 mts to 5000 mts height range. Furthermore, 296 glacial lakes are situated at the height greater than 5000 mts.

The types of glacial lakes are distinct based on how their formation has been done.

The types of glacial lakes are:

1.Moraine Based: The lakes evolved the due to deposition of rocks, sediment, and debris {called Moraine} by glaciers at their edges in their way when they move ahead or when a glacial recession happens. Now this Moraine- deposits of rocks, sediment, and debris act as a natural dam or impediment to the free-flowing water, thereby creating lakes. These lakes are located in the valleys and basins where the deposits are deposited owing to the farthest end of the glacier, called as terminal moraines. When the glacier recessions the Moraine-based lakes are created.

2.Ice-Dammed : These lakes are formed when the water flow is impeded by the glaciers or ice-sheets ; particularly in the valleys or channels.

3.Erosion -Based : Erosional rivers or Erosion-based rivers are V-shaped rivers; rivers formed due to the erosion process. These rivers have attributes such as v-shaped valleys and steep gradients. The water flow is hindered due to the dips and hollows owing to erosion of deposits and hence erosion - based lakes are formed.

4.Other Glacial Lakes: These are the rivers created due to some of the geological factors, climate factors, changes in the sea levels, and glacial factors -such as erosion and deposition of glaciers.

Now let us get back to the observations by ISRO:-

As per ISRO, a significant number of expanding glacial lakes i.e. 307 are moraine-based glacial lakes, 265 lakes are erosion-based rivers, 8 lakes are ice-dammed ones, and lastly are the other glacial lakes which are 96 in number. These number of glacial lakes are out of 676 lakes which are increasing in their size.

Our Bharatiya space agency ISRO has emphasized the permanent changes done at the Ghepang Ghat Lake situated in the Indus basin at an altitude of 4,608 meters in Himachal Pradesh. But, what are these changes which are being focused upon? As per ISRO, from the period between the year 1989 to 2022 period, the Ghepang Ghat glacial lake has expanded from 36.49 hectares to 101.30 hectares i.e. 178% peak in its size. The expansion lake is observed to be 1.96 hectares annually.

Now let us focus on how the glacial lakes can be a potential threat as well in the low-lying areas such as outbursts of these lakes leading to floods.

But before that let us ponder on the significant information. Last year, the month of October witnessed a burst of Lhonak Glacial Lake due to heavy rains. About 40 people lost their lives and 76 could not be found due to the outburst of Lhonak Lake.

But why the Himalayan snow cover is getting influenced at large?

Due to the snow cover and the presence of glaciers over the entire Himalayas, the Himalaya is marked as the third pole. The glaciers are receding owing to climate impacts such as global warming, pollution, afforestation, etc.

This recession of glaciers are cornerstone for forming fresh glacial lakes and the increment in size of the already located glacial lakes. These glacial lakes are a resource of freshwater sources in the Himalayan areas. However, these glacial lakes can be a potential threat to low-lying areas. But how?

The risk of floods due to outbursts of glacial lakes {GLACIAL LAKES OUTBURST FLOODS-GLOFs} does occur due to the gradual degradation of natural dams-which are deposits of rocks, sand, sediments or due to melting of glaciers which increase the size of these lakes. The natural dams may degrade due to avalanches in the snow cover. Other factors leading to the outburst of glacial lakes are intense rainfall, earthquakes, breaking of glaciers into water bodies.

The major challenge in careful examination of glacial lakes is the rocky terrain and difficult-to-reach locations. Here in this difficult situation, satellite monitoring comes to the rescue. This is an ideal way to monitor these difficult terrains, glaciers, and glacial lakes owing to the ability to monitor at large distances and its ability to monitor the same location at greater frequencies-referred as revisit time of a satellite {RT}.

Conclusively, we can say that tight monitoring of these glacial lakes is vital for getting a know-how of recession rates of glaciers and analysis of expansion rates of the glacial lakes.

Thank You.

REFERENCES:

https://indianexpress.com/article/india/satellite-monitoring-shows-large-expansion-in-27-pc-identified-glacial-lakes-in-himalayas-isro-9285392/