Bhutan glacial lake burst triggers flood alert in north Bengal, residents evacuated

Kolkata: A glacial lake outburst flood (GLOF) at Shintaphu Lake in Bhutan has prompted the West Bengal government to prepare for possible flooding in north Bengal. The outflow has raised fears of inundation in the region.

The Torsa, Jaldhaka, Sankosh and Raidak rivers enter north Bengal from Bhutan. Residents living along the banks of the Sankosh are particularly anxious following the sudden release of water from the lake.

Although an alert was issued on Thursday night, the river’s water level had not risen significantly by Friday morning. The situation changed in the afternoon, when the water level began rising sharply in several stretches, raising concern.

On Thursday evening, a large volume of water suddenly flowed out of Shintaphu Lake in Gasa district in Bhutan. The lake was formed by the accumulation of glacial water. The outflow damaged infrastructure near the Gasa Shachu hot spring and led to a rise in the water level of the Mo Chhu River.

The full extent of the damage in Bhutan is not yet known. Preliminary reports suggest that an irrigation project in Punakha has suffered partial damage. A stretch of the Punakha-Gasa road has also been washed away by floodwaters, disrupting traffic.

On preparations following the GLOF at Shintaphu Lake and its impact on north Bengal, state Minister Nisith Pramanik said, "Reports have just come in regarding a glacial lake outburst in Bhutan. Water from the lake is overflowing and flowing downstream into the Mo Chhu River, heading towards the Sankosh River. Residents living along the Sankosh River and its tributaries have been alerted. They have been advised to move to a safe place immediately to ensure their safety."

The minister further said, "The flood water is expected to reach the plains within the next 5 to 6 hours, creating a high risk of significant flooding in the area. To manage the situation, the State Disaster Management Team has been activated, and the NDRF has also been notified. Disaster management volunteers have been instructed to be present on-site. The government is taking proactive measures and closely monitoring the situation to prevent any loss of life or property."

Shintaphu is among 17 lakes in Bhutan identified as dangerous due to glaciers. The lake had also witnessed a sudden rise in water on August 26, 2021, causing the Mo Chhu River to overflow and change its course. The hot spring was washed away then.

The Sankosh is known as the Puna Tsang Chhu in Bhutan. Originating in northern Bhutan, the river flows through Assam and West Bengal before joining the Brahmaputra. The Mo Chhu is one of its two largest tributaries. A substantial rise in the Mo Chhu after the outburst could, therefore, affect the water level of the Sankosh downstream.

Following the flood warning in north Bengal districts bordering Bhutan, residents of areas along the Sankosh were evacuated to relief camps. Many spent the night on the national highway in fear. However, after seeing the river appear calm on Friday morning, several residents of Kumargram block in Alipurduar district wanted to return home. Some began making their way back.

As the water in the Sankosh became increasingly muddy, many changed their minds and returned to the relief camps.

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