The impact of coal mining subsidence on surface ecology involves the influence of several ecological elements such as water, soil, and vegetation, which is systematic and complex. Given the unclear understanding of the synergistic change patterns of the water–soil–vegetation ecological elements in the influence of coal mining in the west, this paper investigates the impact of coal mining on the surface ecology, especially the distribution of soil water content (SWC). In 2020, this study collected 3000 soil samples from 60 sampling points (at depth of 0–10 m) and tested the SWC. All samples come from three different temporal and spatial areas of coal mining subsidence in the desert mining area of Northwest China where soil types are mainly aridisols. At the same time, the interactions among deep SWC and surface soil physical and chemical properties, surface SWC and soil fertility, and pH were analyzed. The spatial variability of soil moisture is reflected by kriging interpolation, and SWC values at different depths are predicted as a basis for monitoring the environmental impact of different coal mining subsidence years. The research has shown that the ground subsidence leads to a decrease in SWC value and changes in surface soil pH, physical and chemical properties, and covering vegetation, which have occurred from the beginning of coal mining. The impact of coal mining on the SWC of the unsaturated zone is mainly at the depth of 0–6 m, where SWC is not directly related to the nutrient content of the surface soil. The overall settlement of the ground will stir up simultaneous decline in the quality of deep SWC and topsoil. The findings of this investigation suggest that changes in the soil structure caused by coal mining subsidence are the key factor in SWC loss. Timely monitoring and repairing 0–6 m ground fissures, as well as selecting shrubs on the surface is the best choice for the restoration of the ecological environment and prevention of soil erosion in this area.

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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.

The current research only investigates the impact of coal mining on deep soil moisture from the perspective of the absolute value of soil moisture. This study applied the combined method of classical statistics and multi-dimensional geo-statistics to analyze the temporal and spatial changes of soil moisture from 0-10m in the mining face of Nalin River No.2 Mine in Northwest China from the perspective of spatial variability. The results of the study showed that in time distribution, on the whole, the soil moisture in the partial areas of the 1-year and the 2-year subsidence area was lower than that in the control area, and the variability increased, but as the subsidence entered a stable period, the degree of variability decreased; vertically observed, in space distribution, the 0-10m soil moisture in the control area had obvious distribution rules with low spatial variability. However, the spatial variability of soil moisture in the 1-year subsidence area and the 2-year subsidence area increased, and the variability showed a trend of increasing continuously with the increase of depth. During the principal component analysis, it was found that the change of soil texture caused by coal mining subsidence, the change of soil pores microstructure caused by geotechnical deformation, as well as the preferential flow caused by changes in groundwater level were the main reasons for the increasing spatial variability of soil moisture. This study revealed the principles of spatial variability of soil moisture in coal mining subsidence areas in Northwest China, which can provide a scientific basis for the restoration of mining areas.