Lahaul-Spiti Prepares for Glacial Lake Outburst Flood Risk from Ghepan Lake

The Lahaul-Spiti administration has stepped up preparedness against a possible glacial lake outburst flood (GLOF) from Himachal Pradesh’s Ghepan Lake, marking 32 vulnerable locations along the likely flood path, according to Rohit Mullick’s The Times of India report.

The administration has identified 32 residential areas between Sissu and the Sansari border, with 128 locations being marked as potential flood-prone zones. The move comes amid concerns over the rapid expansion of Ghepan Lake, which grew from 36.5 hectares to 101.3 hectares in 13 years.

Ghepan Lake, located at an altitude of 4,070 metres and about 11 km from Sissu, expanded by 178% between 1989 and 2022. Its potential downstream flood path extends for around 90 km through Udaipur to the district boundary.

Lahaul-Spiti deputy commissioner and District Disaster Management Authority chairperson Kiran Bhadana said the Indian Space Research Organisation (ISRO) had alerted the district administration in November 2023 about the lake's expansion and advised precautionary measures.

The administration is carrying out 'highest flood level' (HFL) markings under the National Disaster Management Authority to establish permanent reference points showing potential flood levels.

An early warning system will also be installed at Ghepan Lake this month through the Centre for Development of Advanced Computing (C-DAC), Thiruvananthapuram. The system will monitor the lake's water level and other key parameters and provide timely alerts. It was successfully tested at Sissu Lake in April.

A five-member Geological Survey of India team will conduct a 14-day study of the Ghepan Lake area. The team will assess the lake and its surroundings, measure its depth and water flow, study meteorological conditions and examine areas vulnerable to avalanches and landslides.

The district administration will also send a separate team to assess the lake's current condition.

Ghepan Lake is about 2,464 metres long and 625 metres wide at its broadest point near the glacial snout. It is estimated to hold more than 35 million cubic metres of water.

Rapid response teams have been formed in Sissu and Shashin villages, while residents in vulnerable areas are being trained on disaster preparedness and response measures.

The administration is also constituting a district-level GLOF Monitoring Committee with officials from different departments, experienced mountaineers and other experts. The committee will conduct periodic field inspections and assess risks from loose rocks, unstable terrain and other hazards.

According to a report by the Himachal Pradesh State Centre on Climate Change, the Satluj, Beas, Ravi and Chenab river basins together had 1,619 glacial lakes in 2022.