Glacial lake outburst in Bhutan triggers regional flood alerts

A flood from the Shintaphu glacial lake in Bhutan's Gasa district has washed away road sections and the Gasa Tshachu hot springs, cutting the remote Laya region off by road, and has prompted flood alerts and evacuations downstream in India. Water began pouring out of the lake at around 8:15 pm on Thursday, according to Nagarik News and Baahrakhari.

Damage in Bhutan

Citing the Bhutan Broadcasting Service (BBS), Onlinekhabar reported that the flood swept away the Tshachu area in Gasa, damaged solar irrigation systems in Punakha district along the Mo Chhu river, and carried away a section of the Punakha–Gasa highway at Jomlingthang along with part of the Tongchudrak stretch of the road to Laya. With that road blocked, Laya has no road link to the rest of the country. Nagarik News reported that the Gasa Tshachu hot spring, a well-known attraction, was washed away completely.

The road has been closed to all traffic until further notice, and Bhutanese authorities asked security personnel and others stationed in at-risk areas to move to safety, Baahrakhari and Shilapatra reported. No casualties had been reported as of Friday, according to BBS as cited by Onlinekhabar, and to Baahrakhari, Nagarik News and Shilapatra. Officials said the full extent of the damage and the volume of water released could not yet be assessed because the flood came at night.

Alerts and evacuations in India

The lake's water flows through the Mo Chhu into the Sankosh River, which runs on into India's West Bengal and Assam. Nagarik News reported that alerts were raised in Alipurduar and Jalpaiguri in West Bengal and Dhubri in Assam, and that early estimates had the water reaching the India–Bhutan border within six to eight hours.

West Bengal Forest Minister Manoj Kumar Oraon urged residents of Kumargram, Changmari and nearby areas along the Sankosh late on Thursday to stay alert and move to safety if needed, Shilapatra reported. He said he hoped the devastation seen in Nepal would not be repeated there.

Officials said on Friday that evacuations were under way along the Sankosh and its tributaries in Alipurduar district, The Hindu reported. According to Nagarik News, more than 10,000 people in Alipurduar have been moved to safe places and relief camps, the administration is sounding sirens to warn residents, and the National Disaster Response Force (NDRF), the State Disaster Response Force and disaster management teams have been deployed.

What is still unclear

Shintaphu is one of 17 glacial lakes in Bhutan considered highly vulnerable, according to Nagarik News. Onlinekhabar described the outburst as suspected rather than confirmed, and the cause of the release, the volume of water and the damage are still being assessed.