Watch: Tracing the deadly path of the Nepal-Tibet flash flood

WATCH: TRACING THE DEADLY PATH OF THE NEPAL‑TIBET FLASH FLOOD

Hundreds of people have been killed and an equal number are missing after a sudden, catastrophic flash flood devastated the Nepal‑Tibet border region, destroying entire towns and sweeping away bridges. The disaster has left a trail of devastation that officials and humanitarian agencies are still struggling to assess.

BBC Verify has mapped the flood’s route by analysing verified video footage and satellite imagery. The investigation, led by Merlyn Thomas, shows how the torrent moved from the high Himalayan foothills through the towns of Chobhar and Tenzing, before plunging into the plains of the Lhasa–Kathmandu corridor. The flood’s speed and volume were unprecedented, with water levels rising more than a meter within minutes and carrying debris, vehicles and entire homes downstream.

The most severely affected area is the town of Chobhar, located on the western edge of Kathmandu. According to satellite images released by the United Nations Office for the Coordination of Humanitarian Affairs, the flood swept through the town’s main street, destroying several bridges and leaving a network of roads impassable. Rescue teams report that the collapse of the central bridge has cut off emergency access to the most vulnerable communities.

In the remote village of Tenzing, located in the remote Himalayas, the flood obliterated the main road that connects the village to the nearest town. The village’s only bridge, built in 2015, was washed away, leaving residents isolated. Local authorities are working to establish temporary bridges, but the rugged terrain and ongoing rain make the task difficult.

The flood’s impact is not limited to infrastructure. The rapid rise in water levels has caused landslides that have buried homes and roads. In the Lhasa–Kathmandu corridor, satellite imagery shows a series of landslides that have blocked the main highway, cutting off traffic for several days. The blockage has delayed the delivery of essential supplies, including food, medicine and water purification tablets.

Humanitarian agencies have launched emergency operations to locate missing persons and provide relief to those displaced. The Nepalese government has deployed the Nepal Army and the Nepal Police to search for survivors, but the dense forest and rough terrain complicate the search. In Tibet, Chinese authorities have also mobilised emergency response teams. The United Nations has called for international assistance to support the affected communities.

BBC Verify’s investigation relied on a combination of open-source intelligence and satellite data. The team cross‑checked videos posted on social media with high‑resolution satellite images from the European Space Agency. The analysis confirmed the flood’s path and the timing of its arrival in each town. The verification process was carried out by a team of experts, including Emma Pengelly, Paul Brown, Charlotte Green, Shayan Sardarizadeh, Yi Ma and Benedict Garman.

The graphic designer Mesut Ersoz produced a series of maps that illustrate the flood’s trajectory. The maps, which are available on the BBC website, show the progression of the flood from the high-altitude source to the lowland areas. They also highlight the key infrastructure that was destroyed, such as bridges and roads.

The disaster has highlighted the vulnerability of Himalayan communities to flash floods. Climate models predict that the region will experience more intense rainfall events in the coming decades. Experts say that better early warning systems, stronger infrastructure and community preparedness are essential to reduce the impact of future disasters.

At the time of writing, the death toll remains uncertain. Preliminary reports indicate that more than 300 people have died, while another 400 are listed as missing. Rescue operations continue in the affected towns, and the government has declared a state of emergency for the region. The international community is monitoring the situation closely, with several countries pledging financial and logistical support.

As the flood’s effects linger, the focus has shifted to rebuilding and recovery. Local authorities are planning to reconstruct damaged bridges and roads, with an emphasis on resilience to future flooding. The Nepalese government has announced a budget allocation for infrastructure improvements in the border region. Humanitarian agencies are also working to provide long‑term support to displaced families, including temporary housing, food assistance and mental health services.

BBC Verify’s investigation demonstrates the power of open‑source intelligence in documenting and understanding natural disasters. By combining verified videos and satellite imagery, the team was able to trace the deadly path of the flash flood and provide a detailed account of its impact. The findings have been shared with humanitarian agencies to aid rescue and recovery efforts and to inform future disaster risk reduction strategies in the Himalayan region.