Evaluation of disturbance by coal mining to groundwater and surface ecosystem

Abstract

Abstract Coal mining disturbs surface ecosystems in coal mining subsidence areas. Based on the groundwater-surface composite ecosystem analysis, we constructed an ecological disturbance evaluation index system (18 indices) in a coal mining subsidence area using the analytic hierarchy process (AHP). Taking the Nalinhe mining area in Wushen Banner, China, in 2018-2020 as an example, the ecological disturbance degree and the weight and correlation of different indicators were determined by implementing fuzzy mathematics, weighting method, and correlation analysis method. After two years of mining, ecological disturbance was the highest in the study area (Grade III) and the lowest in the non-mining area (Grade I). The ecological disturbance in the coal mining subsidence area continued increasing over two years due to coal mining. The ecological disturbance by coal mining cannot be completely mitigated by relying on the self-repair capability of the environment. Coal mining not only directly interfered with the environment, but also strengthened the connection of different ecological indicators, forming multiple ecological disturbance chains such as "coal mining–surface subsidence–soil chemical factors," "natural climate–soil physical factors–soil chemical factors," and "mining intensity–mining thickness–burial depth and mining thickness ratio”; the last disturbance chain increased the ecological disturbance caused by resource mining. The disturbance chain "coal mining–surface subsidence–soil chemical factors" plays a leading role in controlling the ecological disturbance of soil chemical factors. The disturbance chain that controls the ecological component factors in the region remains unknown; however, the analysis of the results reveals that ecological component factors is the most important factor that hinders the restoration of the ecological state in the coal mining subsidence area. This study is of great significance for ecological restoration and governance of coal mining subsidence areas.