Kathmandu, Aug 31: A lake formed after a river was blocked by a landslide in Gyirong County of China’s Tibet Autonomous Region has nearly drained, but authorities warn that serious risks remain upstream and downstream.
According to a statement issued Sunday by China’s Ministry of Water Resources, the latest assessment, based on drone footage, panoramic images and reports from emergency teams at the site, shows that the lake formed on the Purepu Tsangpo River is almost empty and the river has resumed its normal flow.
However, the ministry said significant risks remain in the Chochhen stream, which flows into the Purepu Tsangpo. About 5.6 kilometres upstream from the drained lake, a large depression on the Nepali side of the river still holds around 1.4 million cubic metres of water. The depression sits about 800 metres higher than the lake that had formed after the river was blocked.
Satellite images showed that the water surface in the depression measured about 108,000 square metres as of 11:23 am Saturday. The area had shrunk by around 19,000 square metres from the measurement taken at 7 am the same day.
Chinese authorities have also identified three other waterlogged areas about 2.5 kilometres downstream from the depression. Their combined area is estimated at less than 70,000 square metres.
The ministry warned that both the depression in Nepal’s Chochhen stream and the three downstream waterlogged areas pose significant risks and could contain hidden hazards.
The situation remains fluid despite the main lake largely draining. The ministry said another lake had formed about 2.8 kilometres downstream of the original blockage after a landslide occurred on the Nepali side on Saturday. Water flowing from upstream has already broken through that lake, allowing the river to return to its normal channel.
Chinese authorities also warned that further landslides along riverbanks could block waterways again and create new lakes.
The developments have kept authorities on both sides of the Nepal China border on alert, particularly as water and debris can move rapidly through narrow Himalayan valleys following sudden blockages and breaches.
According to Tibet’s emergency management authorities, a landslide at the Gyirong port area near the Nepal China border had killed 16 people and left 546 others missing as of 6 pm Saturday.
The latest warning indicates that the disappearance of the main flood lake does not necessarily mean the danger has passed. Unstable slopes, trapped water and newly formed waterlogged areas could still trigger sudden surges downstream if another blockage collapses.
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