The Nepal Flash Flood: How a Mountain Became a Wall of Water

On August 26, 2026, a massive slope failure involving glacier ice high in Nepal’s Himalayas triggered a devastating chain reaction. Rock, ice, mud and water raced through narrow valleys and into the river system, with the disaster traveling nearly 100 kilometers downstream. In this video, we break down how the Nepal flash flood happened—from the initial mountain and glacier collapse to the debris-filled surge that traveled through the Bhote Koshi and Trishuli river system. We’ll also look at why steep Himalayan valleys can amplify disasters like this and why scientists are still investigating the precise trigger. At Galchhi, the Trishuli reportedly rose by about nine meters in just 30 minutes. If you enjoy visual explainers about extraordinary natural events and the science behind them, like the video, subscribe, and share your thoughts below.