中尼边境"8·26"冰崩灾害链演进特征及预警启示OA

On August 26,2026,a high-altitude ice avalanche occurred in the Donglin Zangbo(Lhende Khola)Basin on the China-Nepal border and subsequently evolved into a compound hazard chain consisting of ice avalanche,debris avalanche,debris flow and flood,resulting in a severe transboundary disaster.Based on pre-and post-event remote sensing images,digital eleva-tion model(DEM)data,field videos,and hydrological records along the propagation path,the evolution of the hazard chain was reconstructed,and the arrival times,surface velocities,and downstream propagation characteristics at key locations were analyzed.The results show that the hazard chain propagated downstream from the ice avalanche source area for approximately 21.7 km to the vicinity of Gyirong Port,with a debris flow surface velocity of around 19 m/s.It further propagated to the Bidur Trishuli Bridge,with a cumulative runout distance of approximately 74 km from the source area,where the flood-front velocity was ap-proximately 11.7 m/s.Overall,the hazard chain underwent a progressive deceleration process,transitioning from the high-speed ice avalanche and debris avalanche in the upper reaches to the debris flow and flood in the middle and lower reaches.The river distance from Gyirong Port to the Bidur Trishuli Bridge is approximately 52.3 km,with an estimated propagation time of 46~75 min,indicating pronounced spatiotemporal propagation of the hazard chain.Comparison with analogous events shows that elevation drop,valley confinement,entrainment of materials along the path,water recharge,and flow-regime transformation jointly control the long-runout hazard potential of high-altitude ice avalanche hazard chains.On this basis,an early-warning strategy of"source-zone broadband sensing-channel seismic tracking-downstream multi-source verification"based on the concept of"trading space for time"is proposed,providing a reference framework for the monitoring and early warning of high-altitude long-runout hazard chains.