Bhutan GLOF: A glacial lake outburst flood (GLOF) in Bhutan on Thursday has triggered warnings in Indian states, including West Bengal and Assam. The outburst was reported at Shintaphu Lake in Gasa district, with floodwater moving towards Mo Chhu and Sankosh river systems, raising concerns downstream. People near riverbanks have been advised to move to safer places. The incident has renewed concern about dangerous glacial lakes across the Himalayas especially after the recent Nepal, Tibet floods.
What Is GLOF?
(Image: Reuters)
GLOF occurs when a lake formed by melting glacier water suddenly releases a volume of water. Such lakes are usually held back by natural barriers of loose rocks and soil, called moraines, or by ice. If this barrier breaks, water rushes downhill as a flash flood, carrying rocks and mud. The flow of water can damage homes, roads, bridges, power projects, and cause civilian casualties.
Some of the events that can trigger GLOF are melting glaciers, glacier retreat, heavy rain, snowmelt, erosion, earthquakes, and rising water pressure. Climate change has also added concerns as they lead to melting of glaciers. ISRO’s satellite images from 1984 to 2023 to study glacial lakes in Indian Himalayan river-basin catchments identified 2,431 lakes larger than 10 hectares in 2016-17. Of these, 676 had expanded since 1984, and 130 are within India.
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They include 65 in the Indus basin, seven in the Ganga basin and 58 in the Brahmaputra basin. ISRO said 601 of the 676 had more than doubled in size. According to government surveys, there are around 7,500 glacial lakes across the Himalayan range. Nearly 200 of them are considered highly dangerous and need urgent attention. About 10 per cent of all these lakes are in Sikkim, where 25 lakes have been placed in the highly dangerous category.
Vulnerable Areas And Past Disasters
In India, Sikkim, Arunachal Pradesh, Himachal Pradesh, Uttarakhand, Ladakh, Jammu and Kashmir, and parts of the Northeast face GLOF risks. Government assessments have also identified 195 high-risk lakes. Earlier in October 2023, an outburst at South Lhonak Lake in Sikkim had caused floodwater to rush down the Teesta basin, killing people and damaging bridges, roads and hydropower infrastructure. Similarly, the Kedarnath disaster in Uttarakhand in 2013 involved extreme rainfall and flooding, including water releases from Chorabari Lake.
India’s Disaster Preparedness
India’s GOLF preparedness includes Centre’s approval of a Rs 150-crore mitigation programme for Sikkim, Arunachal Pradesh, Himachal Pradesh and Uttarakhand. It also includes measures such as risk mapping, satellite monitoring, early warnings, evacuation plans, and spreading awareness. Recently, Himachal Pradesh achieved a milestone in strengthening disaster preparedness as the state successfully implemented a GLOF Early Warning System at Geepang Gath Glacier, which is located at an altitude of approximately 4,100 metres in Lahaul-Spiti district.