Glacial lake outburst in Bhutan prompts flood alerts and evacuations in West Bengal and Assam

A glacial lake outburst flood (GLOF) in Bhutan has triggered high flood alerts in northern West Bengal and Assam, prompting evacuations along the Sankosh River and its tributaries. Officials said the breach occurred at Lemthang, with water from the lake flowing into the Mo (Mofu) River and then toward the Sankosh.

Water Resources Investigation and Development Minister Nisith Pramanik said in a video message that residents in the catchment areas of the Sankosh and its tributaries were instructed to move to safety immediately. He specifically urged people near riverbeds in Tufanganj and nearby parts of Cooch Behar to evacuate.

State Disaster Response Force and National Disaster Response Force teams have been placed on alert for rescue and relief operations. Darjeeling MP Raju Bista called on residents of the Darjeeling hills, Terai and Dooars regions to stay vigilant and follow official advisories.

Nearly 7.4 million cubic metres of water surged from the breached Shintaphu Lake in Bhutan into the Mo River, raising concerns of a rapid rise in the Sankosh River, which runs along the West Bengal-Assam border. Officials said evacuation measures began late on Thursday night in villages along the Sankosh, with loudspeaker announcements urging residents to move to designated shelters.

The surge could reach border areas within six to eight hours, potentially flooding vulnerable settlements in West Bengal and Assam. The India Meteorological Department also forecast heavy rainfall in Alipurduar on Friday, which could exacerbate the situation.

The incident has raised concerns for the Punatsangchhu project, a major India-Bhutan joint hydropower venture, as a sudden increase in river levels could threaten infrastructure. A special advisory from the Union Ministry of Jal Shakti warned of possible downstream effects in Assam’s Dhubri district and West Bengal’s Alipurduar district.

Assam authorities are closely monitoring the situation. The Chief Minister’s Office posted that the state’s disaster management team is on the ground in Dhubri and prepared to address any downstream impacts. As of early morning, the water level of the Sankosh River was reported as steady, but district administrations and response forces remain on alert.