Floods devastate Nepal-Tibet border

Flash floods and debris flows have swept down a Himalayan valley on the border between Nepal and China, killing hundreds of people and leaving thousands missing, in one of the deadliest disasters in Nepal's recent history.

The disaster struck on the morning of 26 August, destroying the Gyirong border crossing and settlements along a 72-kilometre stretch of the Trishuli River in Nepal.

What happened

Scientists believe the flood was triggered by a huge avalanche of rock and ice from the Langtang Lirung massif in the Himalayas. The avalanche turned into a fast-moving debris flow that swept down the valley, sweeping away villages, roads, bridges and vehicles.

The collapse was so large that it was detected by seismometers around the world.

Experts from Nepal and from British universities, including Reading and Newcastle, have been studying the event.

A busy crossing

The Gyirong crossing, where the Trishuli meets a river flowing from Tibet, is the busiest trade route between Nepal and China, handling around 30 per cent of all trade between the two countries. It is also used by pilgrims travelling to Mount Kailash, which is sacred to several religions.

Large numbers of traders, drivers and travellers were at the crossing when the flood struck.

Rescue efforts

Rescue teams from Nepal and China are searching for survivors, but the scale of the destruction and the remote location are making the work extremely difficult. Many roads have been washed away, and helicopters are being used to reach cut-off communities.

Authorities have issued flood warnings for communities further downstream, in districts including Nuwakot, Dhading and Chitwan.

A history of disasters

The Langtang valley was devastated in 2015, when an earthquake triggered a landslide that buried villages and killed more than 350 people. Last year, a flood caused by a glacial lake bursting washed away the bridge at the border crossing.

Climate change

Scientists say rising temperatures are causing glaciers in the Himalayas to shrink and become unstable, increasing the risk of floods, landslides and avalanches.

Help from abroad

The UK has a large Nepali community, including many former Gurkha soldiers and their families, many of whom are anxiously waiting for news of relatives.

The bodies of some victims have been carried by the river as far as India.