A glacial lake outburst flood in northern Bhutan has put parts of Assam and West Bengal on alert, with authorities watching the Sankosh river system for a sudden rise in water levels.
The outburst was reported on Thursday evening, October 29, at Sintaphu Lake near Wakila Mountain in Lungo, Laya Gewog, in Bhutan’s Gasa district. The lake is also spelt Shintaphu and is known locally as Shintaphu Tsho.
Damage in Bhutan
Floodwaters swept away the Gasa Tshachu hot spring complex and damaged a section of the Punakha-Gasa highway. A solar-powered irrigation system and roads were also affected.
No casualties have been reported, as the area had been evacuated. Warning sirens were activated and precautionary evacuations were carried out in exposed locations.
Gasa Tshachu has been hit before. It suffered extensive damage in a flash flood on August 26, 2021, when the swollen Mo Chhu changed course towards the hot spring.
Water from the lake enters the Mo Chhu, which flows south through Gasa and Punakha. At Punakha, the Mo Chhu joins the Pho Chhu to form the Punatsangchhu, which enters India as the Sankosh. That path is why Indian authorities moved quickly.
The Central Water Commission issued a special flood advisory for West Bengal and Assam, warning of a sudden rise in water levels in Alipurduar and Dhubri districts. Both states were told to monitor the Sankosh closely and take precautions.
In North Bengal, communities along the Sankosh and its tributaries were advised to move to safer locations.
Alipurduar’s Superintendent of Police, Amit Kumar Shaw, said the water flow had eased slightly and the situation was under control, but a red alert remained in force for the Sankosh system.
Shintaphu is among Bhutan’s 17 glacial lakes identified as potentially dangerous. Such lakes form as glaciers melt, and their water can be released suddenly, with catastrophic effects on communities downstream.
Bhutanese authorities are still assessing the damage and have deployed monitoring equipment in the area to strengthen surveillance.
In Assam and North Bengal, officials are tracking river levels in the Sankosh basin. Residents of low-lying areas along the river, especially in Dhubri and Alipurduar, have been asked to follow official advisories and avoid riverbanks until the alerts are lifted.
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