Inside Nepal’s unending cycle of avalanches, floods and landslides

Nepal experienced three major mountain disasters in six weeks. These events matter because they affected connected rivers, carried debris downstream and showed how quickly high-altitude hazards can become regional emergencies.

On August 26, a rock-ice avalanche near the Nepal-Tibet border opened the floodgates of the Bhotekoshi and Trishuli rivers. More than 1,450 people died, and nearly 6,000 remained missing. In late September, a mountain collapse caused a massive landslide in Mustang. On the following Sunday, another rock-ice avalanche flooded the Budhi Gandaki River in Gorkha district.

The Gorkha event sent concrete-like slush through houses, bridges and trekking trails, although no casualties were reported. The Budhi Gandaki later joins the Trishuli downstream, showing how separate-looking disasters can affect one river network. Experts say similar events are becoming more common as mountain conditions change.

A glacial lake outburst flood, or GLOF, happens when water suddenly escapes from a lake formed by melting glacier ice. The released water can surge down a valley with little warning. It matters because mountain communities and infrastructure often lie along the rivers below these lakes.

The article describes the Rasuwa border area being washed away in July 2025 after a superglacial lake burst. It also reports seven GLOFs in the Koshi, Gandaki and Karnali basins between 2020 and 2025. A sudden release can carry rocks, mud and ice, increasing the flood’s destructive force as it moves downstream.

These floods can become cascading disasters. Water may undermine slopes, trigger landslides, destroy bridges and block river channels. The article notes that concrete-like slush swallowed homes, bridges and trekking trails during the Gorkha avalanche flood. Early warnings and forecasting can help people move before the surge arrives.

The recent increase is striking even though the comparison covers different time periods. Researchers recorded 11 glacial lake outburst floods in the Koshi, Gandaki and Karnali basins between 2010 and 2019. They recorded seven between 2020 and 2025, suggesting a faster pace of events.

The human toll has been enormous. The August rock-ice avalanche and resulting floods killed more than 1,450 people, while nearly 6,000 others were still missing. The later Gorkha event swallowed houses, bridges and trekking trails with concrete-like slush. No casualties were reported there, but communities lost homes, transport links and access routes.

The affected places include Rasuwa, Mustang, Gorkha, Manang, Mustang and Humla. Experts warn that cascading effects are making disasters larger. Sudan Bikash Maharjan said such events could become an annual occurrence, although officials cannot predict exactly when or where they will happen.

Cascading disasters occur when one mountain event creates several connected hazards. An avalanche or landslide can suddenly displace water, block a river or release heavy debris. The resulting surge then attacks slopes, settlements and infrastructure farther downstream.

On August 26, a rock-ice avalanche near the Nepal-Tibet border opened the floodgates in the Bhotekoshi and Trishuli rivers. In Gorkha, another avalanche flooded the Budhi Gandaki with concrete-like slush. That material swallowed houses, bridges and trekking trails. The Budhi Gandaki also joins the Trishuli downstream, linking the impacts through the river system.

The danger continues after the first wave. A blocked or overloaded channel can cause new flooding, while saturated or undercut slopes can collapse. The article says these cascading effects are making disasters bigger. Similar floods and landslides have repeatedly affected places including Chame, Mustang and Humla.

High mountain slopes depend partly on frozen ground, ice and snow to remain stable. When these materials thaw or melt, water can enter cracks and lubricate surfaces. That reduces strength and makes rock, ice and soil more likely to move.

John Pomeroy said rapid snowmelt and rainfall increased the lubrication of frozen materials around Nepal’s recent disasters. Glacier melt can also add water to rivers and lakes, while heavier mountain rainfall can rapidly increase pressure on slopes and channels. These forces can combine rather than act separately.

Climate change did not directly trigger the catastrophes, Pomeroy said, but it created preconditions that allowed them to form. The article links similar problems worldwide to thawing frozen ground, rapid snowmelt and glacier melt. More intense mountain rainfall may make these unstable conditions more frequent and harder to manage.

Nepal is especially vulnerable because many communities live below unstable, high mountain terrain. The country also has difficult geography, limited infrastructure and monitoring gaps. When a flood, avalanche or landslide occurs, warnings, rescue operations and repairs can be slow.

The article describes high mountain regions as often impoverished, poorly served by infrastructure, sparsely gauged and far from decision-making centres. They may also be populated by indigenous peoples and divided by international boundaries. Nepal’s border areas illustrate these risks: the August avalanche began near the Nepal-Tibet border and affected major river systems.

This exposure is unfair because Nepal has made negligible greenhouse-gas emissions, while decades of fossil fuel use elsewhere have driven warming. Global temperatures are around 1.4 degrees Celsius above pre-industrial levels, according to Copernicus. Nepal’s August losses exceeded 408.28 billion rupees, while economic growth is expected to slow.

Early-warning systems reduce harm by detecting dangerous changes and sending alerts before floods or debris flows arrive. Hydrological forecasting helps authorities estimate how much water and debris may move through a river. Together, these tools can support evacuation, road closures, emergency supplies and safer infrastructure decisions.

The article says the United States, Switzerland and Canada are developing advanced early-warning and hydrological forecasting systems for related mountain hazards. Nepal’s increasing GLOFs and cascading floods show why these tools matter. Environmentally assessed infrastructure can also help identify safer locations and avoid placing homes, bridges or roads in dangerous channels.

No system can eliminate the hazard. High mountain regions are sparsely monitored, remote and divided by borders, so coverage and coordination remain difficult. Still, better observation, forecasting, land-use decisions and emergency planning could reduce deaths and economic damage as events become more frequent.