Climatic Preconditioning and Catastrophic Slope Failure in High Mountain Asia: A Multiscale Assessment of the 2026 Langtang Lirung Event
DOI:
https://doi.org/10.64862/Keywords:
Langtang-Lirung, Slope-failure, Cryospheric-hazard, Energy-budget, Geomorphic-change, Hazard-cascade, ice-rock avalancheAbstract
On 26 August 2026, a catastrophic rock–ice–sediment failure at Langtang-Lirung, Nepal, triggered a debris-flow and flood cascade through the Bhote Koshi. ERA5/ERA5-Land reanalysis, precipitation-phase and trend analyses (Mann–Kendall and Sen’s slope), gravitational energy estimation, and 2 m WorldView-3 DEM differencing assessed climatic conditions and geomorphic impacts. Annual temperature increased by 0.31 °C decade⁻¹ (1940–2025), while rainfall rose by 64.8 mm decade⁻¹ (1980–2025), with no significant snowfall trend. August 2026 was exceptionally warm and wet across the Hindu Kush Himalaya. Approximately 130 million m³ of detached material had an estimated gravitational potential energy of 2.6 × 10¹⁵ J over a 2300 m descent. DEM differencing at Syabrubesi and Rasuwagadhi indicated 33.2 million m³ of scour, 5.0 million m³ of deposition, and 28.3 million m³ of net sediment export. Findings indicate climatic preconditioning and downstream geomorphic transformation without establishing direct climatic causation, highlighting the importance of integrated atmospheric, cryospheric, terrain, and hydrological monitoring.
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