Severe flooding has struck the Trishuli River Valley in Nepal’s Nuwakot and Rasuwa districts. This region, where Action Against Hunger has been implementing reconstruction and water access programs since the 2015 earthquake, is now facing a disaster with major human and material consequences. Approximately 273 people have lost their lives and nearly a thousand others remain missing. As the death toll continues to rise, entire communities are mourning and many families remain uncertain about the fate of their loved ones.
For nearly ten years, Action Against Hunger and its partners have supported communities in this Himalayan valley in rehabilitating drinking water and sanitation infrastructure. The systems rebuilt along both banks of the Trishuli River enabled thousands of people to regain sustainable access to safe drinking water following the devastating 2015 earthquake. The floods witnessed today are linked to a phenomenon known as a Glacial Lake Outburst Flood, which occurs when a glacier’s moraine dam suddenly collapses after water accumulates at the base of the glacier in the upper reaches of the river in Tibet. Accelerated glacier melt due to climate change, combined with high-altitude rainfall, contributes to this buildup of water. When pressure becomes too great, the moraine gives way, triggering the sudden release of the glacial lake.
“This flash flood is particularly devastating because immense volumes of water surge through a narrow, steep Himalayan valley. They carry with them the material accumulated by the glacier: mud, boulders, sediment, and ice. It is a veritable liquid avalanche moving at extremely high speed through the rugged terrain of the Trishuli Valley, whose waters originate in Tibet before flowing into Nepal,” explains Julien Eyrard, Water, Sanitation and Hygiene (WASH) Coordinator at Action Against Hunger, who oversaw the reconstruction of water networks in Nepal between 2015 and 2025.
These sudden floods leave communities with very little time to react and are extremely difficult to predict in these remote Himalayan regions. The town of Bidur, where Action Against Hunger teams coordinated their operations in the Trishuli Valley, was completely destroyed and swept away by the floodwaters. Essential infrastructure has also been severely affected. Water supply systems and agricultural land have sustained extensive damage, compromising access to safe drinking water and threatening the livelihoods of many families.
“While these events are becoming increasingly likely as a result of global warming, they remain extremely difficult to predict. In Europe as well, certain glacial lakes are subject to enhanced monitoring, particularly in the Mont Blanc massif. Unfortunately, in Asia, not all high-risk areas benefit from equivalent monitoring and early warning systems,” recalls Julien Eyrard.
According to preliminary information provided by local authorities, nearly 8,700 households, representing more than 39,000 people, are believed to have been directly affected by the disaster. The catastrophe comes in the middle of the harvest season, raising fears of a major food security crisis for riverside communities whose crops and farmland have been severely impacted.
Action Against Hunger teams, in coordination with local authorities and partners, are currently mobilized to assess the full extent of the damage and identify priority needs. Initial assessments indicate significant needs in access to safe water, sanitation services, and food security support across the affected areas.
