Land Deformation and Debris Flow Simulation of the 2024 Wayanad Landslide Using DinSAR, RAMMS, and Slope Stability Modelling

The devastating Mundakkai-Chooralmala landslide of 30 th July, 2024 in Wayanad district, triggered by anomalously intense monsoonal rainfall, necessitated a comprehensive investigation integrating Sentinel-1, debris flow dynamics, and geotechnical stability analysis. This study combines land deformation analysis using Sentinel-1 Synthetic Aperture Radar (SAR) imagery, debris flow simulation via RAMMS: Debris Flow model, and slope stability modelling to decipher the causative mechanisms and dynamic behaviour of the event. Interferometric SAR (InSAR) time-series analysis revealed progressive pre-failure ground deformation across critical slope sections, with anamolous displacements in the weeks preceding failure. These deformations spatially correlated with areas of vegetation loss and lithological discontinuities, as detected from multitemporal Land Use & Land Cover (LULC) analysis. RAMMS-based debris flow simulations were conducted using high-resolution DEMs and field-estimated rheological parameters, including friction coefficient (μ), entrainment coefficient (0.0025), and maximum debris height threshold. The simulated flow path, velocity profile, and deposition thicknesses correspond well with observed post-disaster satellite imagery. Slope stability modelling (HYRCAN) under transient pore pressure from rainfall infiltration showed a decline in the Factor of Safety (FoS) during peak saturation. Saturation-driven reduction in root cohesion (10.4 to 5.3 kPa) and internal friction (29° to 10°) significantly affected slope strength. Long-term forest degradation and rapid urbanization (Buildup increased from 7% to 16%, Trees declined from 82% to 69% over the period 2017-2024) significantly reduced mechanical root reinforcement, acting as a key destabilizing factor. The integrated approach reveals that the 2024 Wayanad landslide was a compound failure involving both deep-seated translational sliding and channelized debris movement. The combined D-InSAR, RAMMS, and slope stability modelling framework offers valuable insights for early warning and risk management in landslide-prone mountainous terrains like the Western Ghats. Poster presented at: AGU Meeting 2025; Dec 17, 2025; New Orleans, LA. Session NH33G: Landslide Life Cycle: From Hazard Analysis to Risk Assessment VI. Final Poster No. NH33G-VR8791.