New threat after Nepal floods: China warns barrier lake could burst

Beijing: China has issued a Level-IV emergency alert in Tibet after devastating flash floods near the Nepal border created a massive barrier lake, warning that a possible breach could trigger further flooding downstream.

China's Ministry of Water Resources issued the alert on Thursday night over the newly formed lake near the confluence of the Chhochen Khola and Purepu Tsangpo rivers. Both rivers originate in Tibet before flowing into Nepal as part of the Bhote Koshi river system.

China's four-tier natural disaster emergency response system places Level I as the highest and Level IV as the lowest level.

The barrier lake had accumulated an estimated two million cubic metres of water by Thursday morning, state-run Xinhua news agency reported. Continued rainfall could push inflows to around three million cubic metres over the next three days, raising concerns that the lake could breach and send floodwaters downstream.

A breach could pose a fresh threat to areas including Gyirong Port, located along the China-Nepal border, as well as other downstream locations.

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The Ministry of Water Resources has directed local authorities to closely monitor the lake and rainfall, improve forecasting and risk assessments and identify people living in potentially vulnerable downstream areas.

China has also stepped up the use of satellites and drones in rescue and assessment operations in the flood-hit region.

The China National Space Administration said it had deployed satellite resources for emergency imaging and retrieved historical images of the affected area. So far, it has provided five pre-disaster images and 10 post-disaster images to emergency response and disaster relief agencies.

Authorities have also deployed a Wing Loong unmanned aerial vehicle equipped with high-definition cameras to conduct reconnaissance, Xinhua reported.

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Rescue teams are using smaller drones to build 3D models of the affected areas, helping command centres assess the situation and identify priority search zones. Thermal imaging equipment is also being used to detect human heat signatures in vegetation and areas covered by mud.

According to Chinese authorities, 558 people, including many foreign tourists, were reported missing after flash floods struck Gyirong Port in Gyirong County near the Tibet-Nepal border on August 26.

The rescue operation has been complicated by the newly formed barrier lake, which Chinese officials fear could trigger a secondary disaster.

An eight-member advance team from China Anneng, a state-owned engineering and rescue company, arrived in Gyirong County on Thursday carrying communications and detection equipment. The team is collecting data and assessing the upstream blockage and barrier lake, which officials have identified as a priority.

Rescue personnel said the debris that has accumulated around three kilometres upstream of the port can only be safely cleared after the threat from the blockage or barrier lake is addressed, Xinhua reported.

Firefighters have been using drones to mark points around the lake's perimeter to calculate its surface area. Drone footage showed that the water level had risen compared with Wednesday night.

Chinese Premier Li Qiang visited the disaster-hit area on Thursday along with senior officials from relevant departments to assess the damage and oversee rescue and relief operations.

A directing group of the People's Liberation Army Western Theatre Command, which is responsible for the India-China border region in Tibet, was also sent to the affected area to coordinate military rescue operations in Gyirong County.