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A glacial lake outburst in Bhutan has triggered a flash flood, washing away infrastructure at the Gasa Tshachu natural hot springs and prompting flood alerts in parts of India’s West Bengal and Assam over fears of rising water levels downstream.
The flood occurred late Thursday (October 29) after an outburst in a glacial lake in Bhutan’s Gasa district. An artificial lake was subsequently formed at Taktsemakhang, where the Sintaphu Chhu and Lungu Chhu, also known as Gangchen Tag Chhu, meet, according to Bhutan Times.
Authorities have advised people living along the Mochhu and Punatsangchhu river valleys to remain vigilant and avoid riverbanks and flood-prone areas.
No casualties have been reported in Bhutan, state broadcaster Bhutan Broadcasting Service (BBS) said on Friday.
The late-night flood damaged infrastructure at the popular tourist destination of Gasa Tshachu, although the full extent of the destruction remained unclear.
BBS said damage assessment was hampered by darkness and the strong flow of floodwaters. Two Bailey bridges may also have been washed away.
According to Bhutan’s national newspaper Kuensel, sections of the road leading to Laya village, where the hot springs are located, were washed away, leaving the route impassable. The road has been closed to traffic indefinitely.
The area was evacuated before floodwaters reached the hot springs, the newspaper reported.
Alerts in West Bengal and Assam
The outburst has raised concerns in neighbouring Indian states, particularly along the Sankosh River, which carries water downstream from the affected river system.
West Bengal Forest Minister Manoj Oraon alerted residents along the Sankosh River in the Kumargram area of Alipurduar district late Thursday, warning of possible flash floods.
He urged people in Kumargram tea estate, Kumargram forest village, Pakriguri and Bholka to remain alert to rising water levels and take necessary precautions.
Local authorities have begun moving people from vulnerable riverbank areas to safer locations. Residents in some villages were also seen leaving their homes with cattle following administrative instructions.
West Bengal Water Resources Investigation and Development Minister Nisith Pramanik said a glacial lake outburst had occurred at Lemthang in Bhutan, sending water through the Mo River towards the Sankosh.
Meanwhile, the Assam government placed Dhubri district on alert over possible downstream effects of the flood.
“The situation arising out of the Glacial Lake Outburst Flood in Bhutan is being closely monitored by HCM Dr @himantabiswa,” the Assam Chief Minister’s Office said in a social media post.
The affected Shintaphu Lake, located below Wakila Mountain in Lungo, Laya Gewog, is among 17 glacial lakes in Bhutan identified as potentially dangerous, according to local reports.
Gasa Tshachu was also hit by a flash flood in 2021 when the Mochhu River changed course and swept through the area.
The latest incident has renewed concerns over the growing threat of glacial lake outburst floods across the Himalayan region, where rising temperatures and melting glaciers are increasing risks to downstream communities and infrastructure.