Rising global temperatures lead to faster melting of ice in these lakes.
The expanding glacial lakes in the Himalayas are a matter of serious concern and the National Disaster Management Authority or NDMA has finalised a list of 189 "potentially dangerous" lakes.
NDTV has learnt that of the nearly 7,500 glacial lakes in the Indian part of Himalayas, NDMA has finalised a list of 189 lakes where the risk factor needs to be lowered.
Rising global temperatures lead to faster melting of ice in these lakes and pose a risk of flooding - a situation known as Glacial Lake Outburst Flood or GLOF.
This is the kind of flood that had devastated the Kedarnath valley in 2013 and parts of Chamoli in 2021, sources said.
In October last year, the South Lhonak Lake in North Sikkim breached, causing a Glacial Lake Outburst Flood.
The destroyed ITBP post on Oct 4, 2023 at Zanak, 6 km downstream of South Lhonak.
The Teesta III dam, the biggest hydropower project in Sikkim was decimated by a GLOF, which also unleashed devastation on downstream areas and communities.
The flash flood of Oct 3, 2023 destroyed Teesta 3 dam at Chungthang
Now, "all central and state agencies are working closely and have already completed expeditions to 15 of these high-risk lakes -- six in Sikkim, six in Ladakh, one in Himachal Pradesh and two in Jammu and Kashmir," a senior official told NDTV.
Another seven expeditions are underway, he said.
"Given the inhospitable terrain and weather conditions at heights of 4,500 m and above, there is only a June to September window to approach these formidable lakes. Several visits will be needed to implement lake-lowering measures, some of which could require civil engineering," he said.
One such expedition is going on in Arunachal Pradesh, where teams are assessing threats from six high-risk glacial lakes.
Considering the risk of these glacial lakes, the NDMA has suggested that there is an immediate need to take up measures to mitigate the effects of Glacial Lake Outburst Flood. The measures being considered include early warning systems, automatic weather stations, and others, the sources said.
"These composite expeditions are assessing structural stability and potential breach points of glacial lakes, gathering relevant hydrological and geological samples and data, measuring water quality and flow rates, identifying risk zones and making downstream communities aware," said another official, explaining the work being done by NDMA.
The National Glacial Outbhrst Flood Risk Mitigation Programme (NGRMP ) was approved by the government on July 25.
The Home ministry has allocated Rs150 crore to support the efforts of state governments of Himachal Pradesh, Uttarakhand, Sikkim and Arunachal Pradesh in this matter.
There is a separate programme envisaged on the same lines for Jammu and Kashmir and Ladakh.
The programme aims at detailed technical hazard assessments, and installing automated weather and water level monitoring stations (AWWS) and early warning systems (EWS) at the lakes and in downstream areas.
The NDMA has indicated that the Uttarakhand government is also evaluating the risk of Glacial Lake Outburst Floods. Thirteen of the most vulnerable lakes in India are in Uttarakhand.