Nepal floods triggered by ice-rock avalanche: Nepalese scientists

Kathmandu, Nepal experienced devastating floods on August 26, triggered by a massive ice-rock avalanche in the high Himalayas, according to preliminary research by Nepalese scientists. The Nepal Environment Society commissioned the study, which found that the disaster was not caused by conventional rainfall or a glacial lake outburst flood.

A significant mass of ice, rock, and debris broke away from the Langtang-Lirung area at around 5,200 metres, plummeting down steep terrain and entering the Lhende River. The resulting surge raced downstream through the Bhotekoshi and Trishuli rivers, causing extensive damage and claiming lives.

Analysis of satellite imagery, hydrological and meteorological data revealed that the ice-rock mass traveled approximately 22 kilometres to Rasuwagadhi in just over seven minutes, reaching average speeds of 46.3 metres per second, or 167 kilometres per hour. The flow continued carrying immense quantities of rock, sediment, and soil as its speed slowed downstream.

The disaster devastated towns and villages in northern and central Nepal, affecting 13 hydropower projects and one solar project, accounting for around 431 MW of generation capacity. Preliminary government assessments estimate economic losses at around ₹3 trillion, though detailed sector-wise evaluations are still underway. Further field investigation is needed to fully understand the geological mechanism and the role of melting ice in the disaster.