Atmospheric Rivers as Triggers of Slope Instability and Landslides in the Himalayas

Landslides are among the most destructive natural hazards in the Himalayan region, where steep terrain, complex lithology, heterogeneous soil cover, and intense hydro-meteorological forcing collectively govern slope instability. Despite growing recognition of ARs as major contributors to extreme rainfall, their explicit integration into physically informed slope stability assessments in the Himalayas remains limited. This research aims to investigate the impact of atmospheric-river-driven precipitation on slope stability across the Himalayan region by coupling landslide inventory data, soil characteristics, topographic controls, and slope stability theory. landslide occurrences are analyzed with respect to topographic parameters derived from digital elevation models, such as slope angle, elevation, and terrain morphology. Given the limited availability of site-specific geotechnical data over large mountainous regions, soil mechanical properties specifically cohesion and angle of internal friction are inferred from soil type and texture classes obtained from global soil databases. Representative ranges of shear strength parameters are assigned based on established values reported in the literature.

Temporal characteristics of AR events, including shape, movement, intensity, duration, and antecedent moisture conditions, are linked with observed landslide occurrences to identify critical thresholds associated with slope failure. Slope stability is evaluated using the factor of safety (FOS) concept derived from limit equilibrium principles for infinite and shallow slope conditions. The influence of atmospheric rivers is incorporated through rainfall-induced changes in pore-water pressure and effective stress, enabling assessment of strength reduction and progressive destabilization under extreme precipitation scenarios. The outcomes of this research are expected to quantify the degradation of slope stability associated with atmospheric-river-driven rainfall, identify soil and terrain combinations most susceptible to AR-induced failures, and provide a physically meaningful explanation for observed landslide spatial clustering during extreme precipitation events. By integrating atmospheric processes with geotechnical slope stability analysis, this study advances the understanding of hydro-geomorphic hazards in the Himalayas and contributes to improved landslide susceptibility assessment, risk mitigation, and climate-resilient land-use planning in mountainous regions.