A cascading high-mountain disaster

A rock–ice avalanche high in the Lhende catchment generated a destructive flood that travelled through Rasuwagadhi and the Bhote Koshi–Trishuli river system.

Source failure

On the morning of 26 August 2026, glacier ice and underlying bedrock detached high on the Lirung massif near the Nepal–China border. HiRISK’s rapid hazard assessment places the source near 28.288708°N, 85.528159°E, at approximately 5,000–5,200 metres elevation. The assessment identifies the event as a rock–ice avalanche and flood.

Post-event satellite imagery indicates a detachment approximately 1–1.3 kilometres across. The failed mass descended to the valley floor below 3,000 metres, mobilising additional material and temporarily blocking the Lhende Khola.

Flood release and downstream travel

Failure of the temporary blockage released a powerful mixture of water, sediment and boulders. The flood wave reached the Rasuwagadhi border area at about 08:44 NPT. HiRISK estimates upper-reach flow velocities above 30 m/s.

The wave then travelled through the Bhote Koshi and Trishuli system. The technical assessment reports propagation for more than 130 kilometres to Mugling by approximately 13:00 and substantial new sediment deposits along roughly 100 kilometres of the corridor to Ghalchhi.

Climate context

The source glacier retreated about 450 metres between 1990 and 2020. Glacier retreat can remove support from adjacent slopes, while warming permafrost may contribute to instability. Current assessments describe these as plausible contributing processes; they do not establish a definitive climate attribution for this individual collapse.