Hydro-gravitational dominance and differential landslide deformation unveiled by SBAS-InSAR-enhanced susceptibility mapping in Wushan, Three Gorges
摘要
Conventional landslide susceptibility maps for China’s Three Gorges region primarily rely on static inventories and slope-gradient analysis, potentially overlooking other contributing factors. Using seven machine-learning models with eleven conditioning factors, we found that elevation and monsoon rainfall showed the strongest statistical association with historical landslide distribution, together accounting for approximately 90% of the aggregated feature importance, while slope gradient contributes only 11%. Five years of Sentinel-1A SBAS-InSAR data further revealed active deformation in areas not captured by the static inventory. Deformation fields reveal spatially variable subsidence patterns—river-facing toes subside at 12–40 mm yr⁻1, with subsidence rates decreasing toward the crest. Incorporating these deformation data into the best-performing CNN model resulted in susceptibility upgrades for 43% of pixels and a threefold increase in the very-high susceptibility zone, reclassifying five planned villages as very-high-hazard areas. Moreover, deformation acceleration lags extreme rainfall by three to five days, suggesting time-lagged pore-pressure buildup rather than instantaneous surface runoff response. These findings demonstrate that hydro-gravitational loading is a primary triggering mechanism in high-relief monsoon settings and provide a transferable framework for landslide-risk forecasting in rapidly urbanizing reservoir regions.