Mains: GS-3 disaster management, climate change and preparedness in the inter-state plains; GS-1 Himalayan geography and river basins.
Prelims: the Sankosh river, the Mochu basin, GLOF, NDMA, the Central Water Commission.
Why in the News
On 29 October 2026, a glacial lake outburst flood, or GLOF (Glacial Lake Outburst Flood), occurred at the Shintaphu (Sintaphu) glacial lake in the Mochu sub-basin in Bhutan's Gasa district. Bhutan's National Center for Hydrology and Meteorology (NCHM) reported it and began monitoring the water level at Tashithang on the Mochu river. According to officials, an estimated about 7.4 million cubic metres of water are expected to have been released from the lake; this figure is still an initial estimate, not a measured flow volume.
The lake's water moved through the Mo (Mochu) river towards the Sankosh river. The Sankosh is a river that emerges from Bhutan and flows along the border of West Bengal and Assam. According to news reports, the Central Water Commission (CWC) under the Ministry of Jal Shakti on 29 October issued a special advisory for Assam's Dhubri and West Bengal's Alipurduar districts, warning that the water level in the Sankosh could rise suddenly. It was the Indian Embassy located in India that gave the first information about the GLOF to the Indian system.
What Is the Situation on the Ground
Evacuation and preparedness: Evacuation began late Thursday night itself in the Sankosh-side villages of Alipurduar. In the Rampur-I gram panchayat area, people were told over loudspeakers to move to shelter sites. The state's water resources minister Nisith Pramanik, in a video message, appealed to all residents of the catchment of the Sankosh and its tributaries to move to a safe distance. The low-lying areas of Tufanganj in Cooch Behar and nearby were also asked to evacuate. SDRF and NDRF teams are on alert.
Special caution for forest villages: Forest and Environment Minister Manoj Kumar Oraon issued a special warning for the forest villages and tea-garden settlements along the Sankosh - Upper Sankosh forest village, NKC Sankosh tea garden, Kumargram, Chengmari, Bhaluka Barabisa and others. Darjeeling's MP Raju Bista asked the people of the hills, the Terai and the Dooars to follow official advice.
The double pressure of weather: The India Meteorological Department (IMD) has forecast heavy rain in Alipurduar on 30 October, which can push the water level higher.
The impact in Bhutan: According to reports, a solar-powered irrigation project in Guma gewog of Punakha district was partially damaged and a section of highway was blocked by debris; there is no report of loss of life in Bhutan so far. There is vigilance also about the safety of the joint India-Bhutan Punatsangchhu hydropower project.
What GLOF Is and Why This Danger Is Growing in the Himalayas
The definition of GLOF: Lakes formed by the melting of glaciers are often ringed by natural dams of ice-moraine (debris). The moment the dam breaks, the accumulated huge mass of water suddenly descends into the valley below - this sudden release of water is called a GLOF. It brings with it a wall-like surge of water, debris and rocks, so its destructive power is many times that of an ordinary flood.
The factors building the risk: The faster melting of glaciers from climate change, the growing size of lakes, ice chunks falling into a lake (which raises a wave of water), seismic activity and substandard construction - all together are raising the Himalayan GLOF risk.
A recent lesson: In October 2023, the GLOF from Sikkim's Lhonak Lake was so destructive that even the Chungthang dam on the Teesta river (the Teesta-III project) was destroyed and the lower valley suffered heavy loss of life and property. The current Sankosh event recalls the same risk chain.
India's system preparedness: The National Disaster Management Authority (NDMA) runs a national programme for glacial-lake risk mitigation; work on identifying sensitive lakes and early warning through the CWC and space-based monitoring is under way. In this event, information through the embassy route and the CWC's immediate advisory - this inter-institutional coordination is the biggest protection tool.
Way Forward
The danger has not passed yet; the next 24-48 hours are decisive for the Sankosh basin. For lasting safety, three steps are necessary - continuous satellite monitoring of sensitive glacial lakes with automatic early warning, a formal India-Bhutan system for sharing water information across the border (as exists with China for the Brahmaputra), and mapped evacuation routes with regular mock drills for riverside settlements. A GLOF-based reassessment of the design-flood capacity of hydropower projects is also indispensable.
Mains Practice Question
"In the Himalayan region, the glacial lake outburst flood (GLOF) is becoming one of the most intense disaster challenges of the climate-change era." In the context of the Sankosh event, review the risk factors of GLOF and India's preparedness system. (Write the answer in 250 words. 15 marks)
Answer Outline
Introduction: Give the definition of GLOF and a brief introduction to the Shintaphu Lake event of 29 October 2026.
Main Body: Risk factors - glacier melt, instability of moraine dams, ice-chunk falls, seismicity, settlement on the plains. Preparedness - NDMA's national programme, the CWC's advisory system, embassy-route information exchange, SDRF/NDRF deployment; along with the gaps - the early-warning time window, the absence of a formal cross-border system, the lesson of the 2023 Sikkim event.
Conclusion: Write the need for three-level strengthening: monitoring, an international information system and local evacuation capacity.
Prelims Practice Questions
Question 1. Consider the following statements with reference to the Sankosh river:
Statement 1: Emerging from Bhutan, it flows through the border region of West Bengal and Assam
Statement 2: The Mochu (Mo) river is connected to its upper basin's water system
Statement 3: It flows towards the Brahmaputra's tributary Manas and falls directly into the sea
Which of the statements given above is/are correct?
(a) 1 and 2 only
(b) 2 and 3 only
(c) 1 only
(d) 1, 2 and 3
See the Answer and Explanation
Answer: (a) 1 and 2 only. The Sankosh emerges from Bhutan and passes through Assam's Dhubri and West Bengal's Alipurduar areas; these same two districts are in the 30 October 2026 warning. Statement 3 is wrong - the Sankosh goes on to join the Brahmaputra system; it does not fall directly into the sea.
Question 2. Consider the following statements with reference to a glacial lake outburst flood (GLOF):
Statement 1: In it, the water of a glacial lake ringed by a moraine dam suddenly rushes into the lower valley
Statement 2: In October 2023, the Chungthang dam of the Teesta-III project was damaged by just such an event at Sikkim's Lhonak Lake
Statement 3: A GLOF occurs only in regions where active volcanoes lie beneath glaciers
Which of the statements given above is/are correct?
(a) 1 only
(b) 1 and 2 only
(c) 2 and 3 only
(d) 1, 2 and 3
See the Answer and Explanation
Answer: (b) 1 and 2 only. Statement 3 is wrong - a GLOF has no necessary connection with volcanoes; it happens when the natural dams of lakes formed by glacier melt break. The Lhonak event (2023) is a proven example.
Sources and References
- The Hindu (Reuters): the Shintaphu Lake GLOF and the Sankosh warning, 30 October 2026
- India Today: damage in Bhutan and alert in 5 districts, 30 October 2026
- Indian Express: the Sintaphu Lake outburst, evacuation in Bengal-Assam, 30 October 2026
This is a developing event. The figure of 7.4 million cubic metres is officials' initial estimate; the details of the CWC's advisory are based on news reports. Further confirmation will attach to the official releases of the Ministry of Jal Shakti/Central Water Commission.
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