Last updated: 27 August 2026, 11:30

Water, debris and mud. A flood struck the Himalayan valleys of the Rasuwa district on Wednesday 26 August, on the border between Nepal and the Chinese region of Tibet, sweeping away roads, bridges and entire villages along the Bhote Koshi river. At least 170 people have died and hundreds are reported missing, a figure that is expected to rise in the coming hours. Two Italian nationals were also caught up in the landslide but are in good condition. Around 90 compatriots were in the area, according to records held by the Farnesina.

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An avalanche of snow, ice and rock

The flood appears to be anomalous — at least in terms of the absence of heavy rainfall in the preceding hours. In short, it did not rain enough to account for a flood of this magnitude. The origin of the event may in fact be different. Nepal's Foreign Minister Shishir Khanal told Parliament that an earthquake, recorded by the US Geological Survey at magnitude 4.4 at 8:37 local time, triggered a large landslide that blocked the Lhende Khola, a tributary of the Bhote Koshi. Subsequent reconstructions, however, suggest that it was the landslide itself that caused the seismic reading.

An avalanche of ice and rock, breaking away from a glacier on the Nepali side, then blocked the course of the tributary and created a natural dam. The accumulated water rose so quickly that it breached the barrier and rushed downstream. And this is not the first time. The same river has flooded twice in fourteen months. This is the mechanism of so-called "cascading hazards": what happens among the glaciers can transform into a flood in the valleys below within minutes.

Among other hypotheses, the possibility of a Glof is also being discussed. In addition to retreating, glaciers form and expand glacial lakes that can burst without warning, generating what are known as glacial lake outburst floods, or Glofs. In the Himalayan-Karakoram region alone, more than 388 Glof events have been documented to date, triggered by ice avalanches and extreme rainfall.

The Himalayas are a fragile territory

The flood has struck one of the most vulnerable parts of the world, where the Himalayan range is warming more rapidly than the global average. A recent study by Icimod (the International Centre for Integrated Mountain Development) documents how the glaciers of the Hindu Kush Himalaya are melting at an accelerating pace, with rates of ice loss that have doubled since 2000. The data reveal a loss of up to 27 metres of ice thickness since 1975 — a warning signal for the nearly two billion people downstream who depend on meltwater from Asia's water towers. The report also records a 12 per cent reduction in total glacial surface area between 1990 and 2020, and a 9 per cent loss in ice reserves. The area's very altitude makes it particularly exposed: approximately 78 per cent of the glacial area, located between 4,500 and 6,000 metres, is highly vulnerable to warming.

With an ongoing climate crisis and a territory undergoing transformation, what is needed is targeted human intervention: satellite imagery to monitor glaciers, lakes and unstable slopes; community early-warning networks and cross-border cooperation between Nepal, China and India; sensors to measure river and stream levels and flows in real time; and automated alert systems that give people enough time to evacuate. Prevention therefore remains the most viable path forward.