From Rock-Ice Slope Failure to Cascading Flood: The Cryosphere-Geomechanical Destabilization Cascade Model (CGDCM) Applied to the 2026 Nepal-Bhote-Koshi and India-Chamoli 2021 Catastrophes

Abstract

The Bhote Koshi-Trishuli catastrophe in Nepal on August 26, 2026, and the Chamoli disaster in India on February 7, 2021, demonstrate how localized high-mountain glacier rock-ice failures can evolve into catastrophic debris-rich floods through interacting cryospheric, geomechanical, geomorphic, and hydrological processes. This article proposes the Cryosphere-Geomechanical Destabilization Cascade Model (CGDCM), an integrative and testable framework that separates climatic-cryospheric preconditioning from proximate triggering and links progressive weakening, threshold failure, rock-ice detachment, pathway amplification, flow bulking, hydro-geomorphic transformation, societal-infrastructure disruption, and legacy risk. In the model, climatic warming acts primarily by progressively altering glacier support, permafrost integrity, rock-ice bonding, meltwater pathways, and slope stability, rather than by determining the precise moment of failure. Nepal provides strong evidence of impact-generated seismicity, fragmentation, and entrainment-driven amplification along a confined pathway, whereas Chamoli provides complementary evidence of multi-year pre-collapse deformation and water-mediated flow transformation. Recent quantitative reconstruction of the Nepal event provides direct empirical support for the CGDCM distinction between source failure, pathway amplification, and flow transformation. The framework emphasizes that warming may progressively condition slope systems toward instability without necessarily determining the precise moment of failure. Five testable propositions address susceptibility, precursors, pathway amplification, hydrological control of flow regime transitions, and exposure and legacy effects. Operationalization emphasizes measurable physical indicators, rates of change, and site-calibrated multivariate anomaly thresholds rather than universal failure cutoffs. The CGDCM is presented as a bounded, transferable analytical framework whose principal contribution lies in integrating established mechanisms into a coherent source-pathway-river-exposure architecture for analysis, monitoring, and anticipatory Cryospheric Himalayan risk governance.

Key words: Climatic Preconditioning; Rock-Ice Avalanche; Process Chains; Cascading Hazards; Permafrost Thaw; Disaster Risk

DOI: 10.7176/JEES/16-2-06

Publication date: October 28^th 2026