Mapping the Spatiotemporal Patterns of Surface Mining in Resource-Based Cities and Assessing Their Impact on Land Surface Temperature Across the Urban–Rural Gradient

Intensive mining activities in resource-based cities can significantly alter the local thermal environment. However, due to the dynamic characteristics and heterogeneous backgrounds of mining areas, it remains challenging to delineate their spatiotemporal extent and assess their impacts. To address this issue, this study integrated multi-source remote sensing data with NDVI and land surface temperature (LST) retrieval methods to map the dynamics of different types of surface mines from 1990 to 2020 in the Hohhot–Baotou–Ordos–Yulin (HBOY) urban agglomeration and to systematically assess their impacts on LST along the urban–rural gradient. A zonal threshold segmentation approach was developed to delineate mining areas under complex backgrounds, while a hierarchical overlay analysis framework within an urban–interface–rural structure was proposed to systematically evaluate the thermal impacts of these different mining types. The results show that surface mining in HBOY expanded exponentially over the past three decades, with surface coal mines mainly distributed in Ordos (72%) and Yulin (16.87%), whereas 96% of non-coal surface mines were concentrated in Baotou. Between 1990 and 2020, surface mining cumulatively disturbed 1,175.1 km² of land, of which 66.43% was grassland and 25.14% was barren land. Mining activities induced distinct thermal responses along the urban–rural gradient. Surface coal mines primarily occupying grassland tended to cause warming, while non-coal surface mines primarily occupying barren land tended to reduce LST. These findings reveal the thermal propagation patterns of mining activities along the urban–rural gradient and offer important insights for balancing resource development and environmental protection in resource-based cities.