Environmental assessments in dense mining areas using remote sensing information over Qian'an and Qianxi regions China

•Developed Iron Mine Remote Sensing-based Ecological Index (IM-RSEI) based on Landsat satellite data.•The characteristics of mining areas and human factors were added.•The environmental impact of dense mining areas on the surrounding area was noticeable.•IM-RSEI can evaluate the ecological status of iron-mine dense areas. Dense mining areas are regions with relatively concentrated mining enterprises or occupied land, which are also regions with intense economic and resource development conflicts and environmental protection. However, ecological assessments by remotely sensed technology do not consider the characteristics of mining areas. To fill the knowledge gap, we employed seven indexes, i.e., fractional vegetation cover, greenness above bare soil, wetness, black particulates, land surface temperature, iron oxides, and the landscape fragmentation index, to construct the iron mine remote sensing-based ecological index (IM-RSEI) by Landsat data. We chose Qian’an City and Qianxi County in Tangshan City, China, as the study area where iron ore-related industries are concentrated. The results showed that the ecological environment generally deteriorated first and then improved that the IM-RSEI values for 1992, 2000, 2009, and 2018 were 0.5102, 0.4776, 0.4882, and 0.5001, respectively. The mean IM-RSEI values for the dense mining area and surrounding multi-gradient buffer zones, from near to far, were 0.5412, 0.5146, 0.5076, 0.4756, and 0.4563, implying that mining activities endangered the surrounding ecological quality. This study assessed the ecological environment in dense mining areas from multiple perspectives by remote sensing technology. The research conclusions can provide a reference for pollution control during mining development in Qian’an, Qianxi, and similar mining areas.