Spatial heterogeneity of soil moisture content and its influencing factors in the center of coal mining subsidence area

Taking typical coal mining area in China as an example, the paper analyzes the changing rule of surface soil moisture content and its leading factor in the central location of coal mining area before and after mining. The research results show that the spatial distribution of surface soil moisture content before mining is mainly controlled by the change of elevation. After mining, the surface soil moisture content in the coal mining subsidence area presents the characteristics of "low on both sides and high in the middle". The coal seam mining destroys the spatial distribution characteristics of surface soil moisture. In a larger rang (900 m), compared with before mining, the surface soil moisture content, total porosity and clay mass fraction in the center of coal mining subsidence area increased by 0.034 cm³/cm³, 7.5% and 0.14%, respectively, while the mass fraction of soil organic matter, soil bulk weight and soil density decreased by 0.05%, 0.08 g/cm³ and 0.24 g/cm³ respectively. The correlation coefficient between soil moisture content and total porosity was the highest at 0.751 (P < 0.01), which was significantly higher than that before mining. In a small rang (50 m×50 m), the surface soil moisture content and total porosity increased by 0.014 cm³/cm³ and 2.9% respectively, while the mass fraction of soil organic matter, clay mass fraction, soil unit weight and soil density decreased by 0.42%, 0.18%, 0.23 g/cm³ and 0.21 g/cm³ respectively, the correlation coefficient between vegetation coverage and soil moisture content was the largest, which was 0.70 (P < 0.01). The analysis results indicate that the main controlling factors of soil moisture change in different areas of the coal mining subsidence area are different, and the results can provide a scientific basis for the reclamation of the coal mining subsidence area.