As a part of the national survey to preempt the Glacial Lake Outburst Flood (GLOF), the National Disaster Management Authority (NDMA) has started surveying the Eastern Himalayas to map all glacial lakes in the country and assess the feasibility of installing early warning sensors and other mitigation measures. The agency is conducting surveys in Arunachal Pradesh and Sikkim, the two important areas of the Eastern Himalayas along the China border.

Expert teams have fanned out to carry out a survey-cum-study at six high-risk glacial lakes in Tawang and Dibang Valley districts in Arunachal Pradesh, which shares a 1,080 km-long border with China. There are reports of the washing away of more than five bridges due to a glacial lake outburst from Sangnga Nehgu Lake in the Tawang district. It is also the first such survey of glacial lakes in the border state.

Sikkim has also sent an expedition of 32 experts to five under-threat glacial lakes – Gurudongmar A, B, and C, Sakho Chu, and Khangchu, all in the Mangan district, which borders Tibet.

The experts will survey the lakes from August 28 to September 14 at an estimated cost of Rs 32 lakh.

The expedition is being led by State Science and Technology Secretary Sandeep Tambe along with experts from six different departments of the State Disaster Management Authority (SDMA) under the Land Revenue Department, Mines and Geology, Water Resources, Forest, Science and Technology and research scholars from Sikkim University.

The expedition will also be aided by the Indian Army and Indo-Tibetan Border Police (ITBP) with a collective manpower of 56 individuals including drivers and porters…

“We are going to do very hi-tech studies to understand the geology of the glacial lake, understand the glacial behaviours, study the slope stability and probabilities of avalanches and GLOF. This will be a study at an altitude of 18,000 feet. Once our study is done, we will plan the mitigation plan,” said Sandeep Tambe, Secretary of the Science and Technology Department, Sikkim.

The previous expedition was carried out by the NDMA and experts from Switzerland before the 2023 lake outburst in South Lhonak in Sikkim.

New Delhi:

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 Teesta III dam, the biggest hydropower project in Sikkim was decimated by a GLOF, which also unleashed devastation on downstream areas and communities. 

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.