Post-mining landscapes present significant environmental and geotechnical challenges due to long-term impacts of underground exploitation, such as ground deformation, subsurface instability, and environmental degradation. Conventional monitoring methods often fall short due to a lack of surface indicators of underlying geological structures. Thus, accurately identifying subsurface discontinuities—such as faults, cavities, and weakened zones is essential for effective environmental risk assessment and sustainable land-use planning. Previously, these challenges were approached using traditional surveying methods, which often lacked precision and were time-consuming. In this study, we introduce an innovative methodology utilizing MOVE software for comprehensive 3D geological modelling and UAV multispectral surveys to acquire detailed surface data. The process is complemented by rigorous field validation, involving the integration of geological, tectonic, and mining maps with borehole logs and seismic profiles. Our results confirm the presence of persistent subsurface discontinuities in historically mined areas, often aligned with tectonic structures, subsidence lakes, and vegetation stress zones. This enhanced mapping of geological discontinuities and the comprehensive stability analysis of embankments demonstrate the methodology's potential to improve geomonitoring accuracy. Furthermore, our framework supports the development of dynamic digital twin models for predictive modelling and environmental risk management. Overall, this integrated approach offers a robust and transferable methodology for addressing subsurface challenges in post-mining and similar environments, ultimately enabling more informed decision-making and long-term planning in areas affected by legacy mining activities.