Comprehensive ecological risk assessment of coal resource development in shallow groundwater areas: a case study of a coal mine in the Huang-Huai-Hai Plain

Ecological risk assessment in mining areas is of great significance for environmental protection, ecological management, and sustainable resource development. Currently, most of the studies have focused on static assessments of heavy metal contamination, whereas ecological risks in coal mining areas arise from multiple interacting sources and involve complex ecological processes. This issue is particularly pronounced in coal mines located in shallow groundwater regions, where mining activities can trigger a wide range of ecological risks. Therefore, there is an urgent need to develop dynamic and integrated approaches for ecological risk assessment in such mining environments. Taking a coal mine in the Huang-Huai-Hai Plain as a case study, this study developed a dynamic ecological risk assessment framework by comprehensively considering both risk-source hazard and ecosystem vulnerability. An indicator system for ecological risk assessment in shallow groundwater coal mining areas was developed using the Analytic Hierarchy Process （AHP）, and a dynamic evaluation was conducted. The results indicate that the secondary effects of risk sources, such as increased subsidence depth and extent, as well as pollutant dispersion, have led to a sharp increase in the hazard level of ecological risk sources associated with coal mining. Compared to 2015, the area of low-hazard regions decreased by 35.90% in 2018, while the areas of moderate and high hazard zones expanded approximately 14-fold and 43-fold, respectively. Ecological vulnerability initially increased and then decreased. The increased subsidence and variations in water depth resulted in high ecological vulnerability in unstable slope ecosystems, whereas in stable waterlogged regions, ecological vulnerability decreased. From 2015 to 2017, comprehensive ecological risk exhibited an increasing trend, with a turning point in 2018. The area of low ecological risk regions began to expand, while high ecological risk regions continued to increase, indicating a polarization trend. Based on these findings, ecological management measures applicable to coal resource development in shallow groundwater areas were proposed. This evaluation system and its corresponding management measures can provide a scientific basis for the rational development, ecological risk prediction, and ecological restoration planning of coal resources in shallow groundwater areas.