ISRO’s findings on the growth of glacial lakes in the Indian Himalayas

Source: The post ISRO’s findings on the growth of glacial lakes in the Indian Himalayas has been created, based on the article “How ISRO used satellite remote-sensing to analyse glacial lakes in Himalayas” published in “Indian express” on 27th April 2024.

UPSC Syllabus Topic: GS Paper 1-geography-changes in critical geographical features (including water-bodies and ice-caps)

News: The article discusses ISRO’s findings on the growth of glacial lakes in the Indian Himalayas, which pose flood risks. It explains how these lakes form, the use of satellites in monitoring them, and strategies to mitigate flood risks, including lowering water levels.

What did ISRO discover about glacial lakes?

ISRO analyzed satellite data from 1984 to 2023, observing the Indian Himalayan river basins.

They found that out of 2,431 glacial lakes larger than 10 hectares, 676 had significantly expanded.

Specifically, 601 of these lakes more than doubled in size, showing substantial growth.

130 of the 676  lakes are situated in India, in the Indus (65), Ganga (7), and Brahmaputra (58) river basins, which have expanded as the glaciers retreated due to global warming.

This data highlights the increased risk of glacial lake outburst floods (GLOFs), posing a threat to downstream communities.

How are glacial lakes formed?

Glacial lakes are formed by the movement and melting of glaciers, which create depressions in the landscape. These depressions fill with meltwater, forming lakes.

Types of glacial lakes:

Moraine-dammed lakes: formed by debris such as rocks and soil left by moving glaciers.

Ice-dammed lakes: formed when water is trapped by ice.

Erosion-based lakes: created by depressions from erosion.

Each type is categorized based on how the water is dammed or held in place.

What are the risks of glacial lakes?

Glacial lakes pose significant risks due to potential glacial lake outburst floods (GLOFs). GLOFs can occur when natural dams, such as moraine or ice, fail to hold back lake water. This failure can be triggered by factors like avalanches of ice or rock. Such floods can cause severe and sudden flooding downstream, endangering communities.

ISRO highlighted the risk with data showing 676 glacial lakes have grown, increasing the potential for dam failure.

How can the risks be mitigated?

Lowering Lake Levels: A study on Ghepan Gath lake suggested reducing water levels by 10 to 30 meters can significantly lessen impact on downstream areas like Sissu town, though not completely eliminate risks.

Using HDPE Pipes: In 2016, the Sikkim State Disaster Management Authority and others successfully used High Density Polyethylene (HDPE) pipes to lower water levels in South Lhonak Lake, reducing flood risks.

Installing Early Warning Systems: Fieldwork at critical lake sites can include setting up instrumentation like motion detection cameras, water level sensors, and discharge meters to monitor for signs of potential GLOFs.

Satellite Monitoring: Utilizing advanced satellite remote-sensing tools helps in continuous monitoring and assessment of glacial lake dynamics, crucial for timely interventions and planning.

Question for practice:

Evaluate the effectiveness of satellite monitoring in assessing glacial lake dynamics and its role in mitigating the risks of glacial lake outburst floods (GLOFs) in the Indian Himalayas.