Bhutan GLOF Triggers Flood Alerts in Assam and West Bengal

A glacial lake outburst flood (GLOF) was reported on the evening of 29 October 2026 in Bhutan’s Gasa district, in the Mochu sub-basin. Accounts identify the lake as either Shintaphu or Sintaphu. The outburst reportedly released about 7.4 million cubic metres of water.

Floodwaters entered the Mo Chhu and Punatsangchhu river systems, which flow towards Assam’s Brahmaputra valley and West Bengal’s northern Duars. India issued a special flood advisory for Assam’s Dhubri, Kokrajhar, Baksa and Chirang districts. For West Bengal, the advisory listed Alipurduar and Cooch Behar; another account also named Jalpaiguri.

Damage and response

In Bhutan, the flood washed away infrastructure at Gasa Tshachu natural hot springs and collapsed at least two Bailey bridges. No casualties were reported, as the area had been evacuated. Assam and West Bengal deployed the National Disaster Response Force and State Disaster Response Force, opened round-the-clock control rooms and advised vulnerable communities to leave riverbeds and prepare for possible flooding.

The event occurred amid rising GLOF risks in the Eastern Himalayas, where higher temperatures are accelerating glacial retreat and expanding high-altitude proglacial lakes. It followed transboundary flooding near the Nepal–Tibet border in August 2026, involving slope failures and glacial lake surges.

Important Facts for Exams

• GLOF failure triggers: A GLOF dam may fail through erosion, rising water pressure, avalanches, earthquakes, cryoseisms, volcanic activity beneath ice or glacier collapse.
• Lake and outburst types: A lake dammed at a glacier front is ice-marginal; a glacier-capped lake is sub-glacial, and their outbursts may be termed marginal drainage and jökulhlaup respectively.
• Moraine-dam instability: Meltwater left by retreating glaciers may be held behind unstable moraines, which can collapse if breached or displaced by earthquakes, landslides or avalanches.
• Ice-dammed lake release: A glacier blocking a river can create a backed-up proglacial lake; the lake may overtop or undermine the ice dam and release water suddenly.