Study of disturbed spatial and temporal evolution dynamics of open-pit mine discharge site based on SBAS-InSAR and NDVI monitoring

Time-series InSAR monitoring technology has emerged as a critical method for monitoring surface subsidence in open-pit mining areas, owing to its high spatial resolution, full-coverage monitoring capability, and non-contact data acquisition. This paper investigates a dump site in an open-pit mine affected by underground mining disturbances. Using SBAS-InSAR technology and 22 Sentinel-1A images, it characterizes the spatial distribution of surface subsidence and analyzes the impact of underground mining on dump stability. Simultaneously, Sentinel-2 data are employed to evaluate vegetation growth responses to subsurface disturbances. The results reveal that surface subsidence in coal mining areas predominantly occurred in underground disturbance zones corresponding to working faces 6108, 4104, and 4106, with maximum subsidence reaching −172 mm. The eastern section of the internal dump exhibites the most severe subsidence （−572 mm）. Four monitoring lines along the NW-SE direction demonstrates funnel-shaped subsidence patterns, with greater deformation magnitudes concentrated in the central internal dump. Time-series deformation analysis indicates progressive expansion of subsidence areas in both the internal dump and underground disturbance zones over time, correlating with evolving stress distribution characteristics. Furthermore, surface subsidence induces by external dump mining triggered groundwater decline and surface fissures, disrupting soil moisture supply and vegetation habitats. Consequently, vegetation growth is significantly impaired, as evidenced by lower NDVI values.