NDMA to monitor 189 high-risk glacial lakes to prevent disasters

The National Glacial Lake Outburst Floods Risk Mitigation Programme was approved by the Centre on July 25; some of the proposed steps include attempting ‘lake-lowering measures’ and mitigating damage in downstream States

Satellite views of Lhonak Lake before (top) and after it burst its banks on October 3, 2023. Photo: Maxar Technologies

Following disasters inflicted by overflowing glacial lakes in the Himalayas, the National Disaster Management Authority (NDMA) has finalised a list of 189 “high-risk” glacial lakes for mitigation measures to reduce the risk emanating from them.

Some of the proposed steps include constituting teams to investigate these lakes and attempt “lake-lowering measures”, which are done to buffer against any overflow, and mitigating potential damage in downstream States.

Last October, the South Lhonak Lake in Sikkim, a glacier-formed lake, overflowed and inundated several parts of the Northeastern State killing at least 40 people and destroying the Chungthang dam.

Central programme

The National Glacial Lake Outburst Floods Risk Mitigation Programme (NGRMP) was approved by the Centre on July 25. There are nearly 7,500 glacial lakes in the Himalayan mountain ranges located in India and some of them are being monitored via remote sensing. However, fully assessing its impact is only possible with site visits, which are difficult as the location of these lakes are in inhospitable terrain and there are only few months in a year — July to September — where expeditions can be mounted to access them.

This week, for instance, the Arunachal Pradesh State Disaster Management Authority has sent two teams to six high-risk glacial lakes in the Tawang and Dibang Valley districts to study them.

The Central Water Commission (CWC) in an October 2023 report stated that 902 glacial lakes and water bodies are being monitored via satellite.

The programme aims at detailed technical hazard assessments, installing automated weather and water level monitoring stations (AWWS) and early warning systems (EWS) at the lakes and in downstream areas. So far, 15 expeditions have been conducted including six in Sikkim, six in Ladakh, one in Himachal Pradesh and two in Jammu and Kashmir. Another seven expeditions are underway.

Multiple visits are often necessary to implement lake-lowering measures, some of which could require civil engineering, the NDMA said in a statement.