31/08/2026
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With thousands of emergency responders conducting search-and-rescue operations following the catastrophic flash flood that struck northern Nepal on 26 August, satellite imagery is helping to reveal the scale of the inundation and devastation across the affected region.
The flash flood and debris avalanche struck the Nepal–China border region on the morning of Wednesday, 26 August 2026, leaving hundreds dead and thousands still missing.
The disaster was triggered by a rapid slope failure associated with a glacier collapse on Langtang Lirung in Langtang National Park. The impact of the collapsed glacier hitting the bottom of a valley was so powerful that it generated energy equivalent to a 5.2 magnitude earthquake.
The resulting torrent of water, ice and debris gushed nearly 100 km downstream picking up more water and rubble as it swept through towns popular with mountaineering tourists and pilgrims, and overwhelming the Gyirong Port border crossing and devastating infrastructure along the Lende Kholā and Trishuli River valleys.
Rescue operations have been complicated by the naturally difficult mountainous terrain, areas that are now cut off, damaged infrastructure, the weather and the continuing risk of further flooding and landslide
Satellite imagery is vital for emergency response teams, providing a rapid and comprehensive view of affected areas that may be difficult or impossible to access from the ground.
For example, the pair of images shown above was captured by the Copernicus Sentinel-2 mission. The image on the left was acquired on 27 August, the day after the event, while the image on the right was captured on 12 August, before the flood. Both images are shown in natural colour, with the post-event image clearly revealing the dramatic increase in river water.
The set of images below has been processed using the satellites’ shortwave-infrared channels, which can help distinguish water and ice from clouds in this frequently cloud-covered mountainous region of the world. The image on the left was captured by the US Landsat-9 mission on 26 August, approximately two hours after the glacier had collapsed, while the image on the right was captured by Sentinel-2 on 24 August, providing a pre-event view for comparison.
The International Charter Space and Major Disasters and the Copernicus Emergency Mapping Service were activated to provide satellite imagery to aid emergency response efforts.
The Charter brings together space agencies and satellite operators worldwide to rapidly mobilise satellite data following major disasters, while Copernicus Emergency Mapping Service provides geospatial information to support emergency response, preparedness and recovery.
ESA is a co-founder and active member of the International Charter Space and Major Disasters, helping mobilise satellite data for rapid disaster response worldwide. In the Copernicus Emergency Mapping Service, ESA supports the service by providing Sentinel satellite data and managing access to complementary Copernicus Contributing Mission data. The two systems cooperate closely, combining ESA’s space-based capabilities with international and EU emergency-mapping efforts.
While satellite imagery is indispensable in the immediate aftermath of a disaster, its value extends far beyond the initial emergency response.
In the weeks, months and even years that follow, satellite data can provide a detailed picture of the damage, help authorities assess which roads, bridges and buildings have been affected, and support efforts to restore essential services and rebuild communities.
By providing a consistent view of the landscape before and after a disaster, satellite imagery can also help planners track recovery, identify areas that remain at risk and make better-informed decisions about where and how to rebuild.