Recent years have seen extraordinarily large events and disasters originating from the high-mountain cryosphere in the Himalaya and beyond. Some of those events in the last five years include the 2021 Melamchi debris flow in Nepal, the 2021 rock-ice avalanche in Chamoli, Uttarakhand, India, or the 2023 South Lhonak GLOF, Sikkim, India.
The most devastating was the 26 August 2026 Rasuwa disaster in Nepal. A very large rock slope failure occurred on the northern slopes of Langtang Lirung (7240 m asl), together with the overlying glacier with an estimated failure volume of 110 to 130 million m3; it produced a rock-ice avalanche that rushed into the Lendhe valley and gradually transformed into a debris flood that devastated the Bhote-Koshi and Trishuli valleys on a length of more than 100 km, through Rasuwa, Nuwakot, Dhading, Gorkha, and Chitwan districts and across the border into Gyirong County, Tibet Autonomous Region. The path of destruction down the valleys is far beyond any historical monsoon-type flood. More than 1,500 people have confirmed dead, around 5,000 are missing, many have been injured, and large number of infrastructures have been damaged or lost. About 10% of Nepal’s hydropower production was wiped away. Total estimated loss as per preliminary estimate is USD 2.7 Billion (6.7% of Nepal’s GDP) and estimated cost for re-building is USD 4.8 Billion (11.8% of Nepal’s GDP).
In this context, understanding the processes behind increasing cases of cryosphere-originated disasters risks in the Himalayan region in South Asia, assessing hazards and residual risks, and identifying ways forward to minimize future risk is critical to support resilient development and planning of societies in the Himalayan region and beyond.
This session aims to bring together the various multi-disciplinary research that has been conducted in the weeks and months after the disaster. It includes but is not limited to aspects such as pre-disaster development in the source area, conditioning and potential preparatory or triggering factors of the initial rock slope failure, attribution to climate change, flow processes and dynamics of the avalanche and debris flood, landscape impact and longer term change, loss and damage estimates, implications for hazard and risk analysis in the region and related recommendations.
We also invite contributions on analysis of other recent large events in the region that can foster insights into the above outlined aspects.