Bhutan Glacial Lake Flood Triggers Warning for Bengal, Assam

A Glacial Lake Outburst Flood (GLOF) at Shintaphu Lake in northwestern Bhutan has triggered flash-flood warnings across parts of West Bengal and Assam. The sudden flood struck the Gasa district on 29 November, 2026 evening. Recognizing the downstream danger, Bhutan immediately alerted Indian authorities to prepare border districts for rising river levels.

The surge of water completely destroyed facilities at Gasa Tshachu, a famous natural hot spring near the Mo Chhu River. Fortunately, authorities evacuated the area before the floodwaters hit, preventing any loss of life. Officials in both Bhutan and India are closely monitoring river channels and warning residents in high-risk zones to stay alert.

Event Summary: Shintaphu Lake GLOF

Shintaphu Lake and the Path of the Floodwater

Shintaphu Lake sits high at the source of the Mo Chhu River. Bhutan classifies it as one of its 17 potentially dangerous glacial lakes. When the lake's natural barrier failed, stored water rushed past Srigang in Kabesa Gewog, just eight kilometers from Punakha Dzong.

The floodwaters washed away the Gasa Tshachu hot spring complex, which had previously suffered major flood damage in August 2021. Further downstream in Bhutan, the flood water damaged a new solar irrigation system in Guma Gewog and dumped heavy rock debris across the Punakha-Gasa Highway near Dzomlingthang.

High Alerts Issued for West Bengal and Assam

Bhutan notified the Indian government that rising water in the Punatsangchu basin would enter Indian river systems. The upper tributaries, including the Mo Chhu and Pho Chhu, feed into the Sankosh River, which flows directly into India before joining the Brahmaputra in Assam.

• West Bengal: Alipurduar, Jalpaiguri, and the Darjeeling hills. Officials issued a dedicated alert for residents along the Sankosh River in Cooch Behar.
• Assam: Dhubri district.

Alipurduar Police Superintendent Amit Kumar Shaw reassured residents that emergency agencies have entered alert mode to secure vulnerable riverbanks.

Central Water Commission Issues Urgent Advisory

The Flood Forecast Monitoring Directorate of the Central Water Commission (CWC) issued a special flood advisory for Alipurduar in West Bengal and Dhubri in Assam.

The CWC warned that high-volume floodwater could cross the Indian border within six to eight hours. The Commission instructed local administrations to track water movement continuously, monitor river gauges, and prepare swift evacuation measures if river levels surge.

What Is a Glacial Lake Outburst Flood (GLOF)?

A Glacial Lake Outburst Flood occurs when a lake formed by melting glacier ice suddenly breaks through its natural dam of rocks, soil, and ice. As rising global temperatures melt Himalayan glaciers, newly formed lakes collect massive amounts of water.

A natural dam can collapse due to several triggers:

1. Intense, heavy rainfall.
2. Mountain landslides dumping debris into the lake.
3. Ice avalanches from nearby peaks.
4. Earthquakes destabilizing natural earthen dams.
5. Rapid glacier melting caused by climate change.

When these dams breach, millions of gallons of water cascade down narrow mountain valleys, destroying bridges, highways, farms, and homes in minutes.

Why GLOFs Threaten the Himalayan Region

The Himalayas house thousands of high-altitude glaciers feeding major river networks across South Asia. A GLOF event in an upper basin travels rapidly downstream into populated plains. The Shintaphu Lake incident highlights the urgent need for cross-border early-warning networks, continuous satellite monitoring of glacial lakes, and coordinated regional disaster plans.