Study on the effect of mining ground fissures on soil moisture distribution in arid and semi-arid regions

Mining ground fissures are among the most significant geological hazards in coal mining subsidence areas, yet a standardized method for classifying and quantifying their spatial impacts across different soil types and fissure scales is still lacking. To address the ecological issue of intensified soil water dispersion caused by surface collapse fissures from underground coal mining in arid and semi-arid regions, this study employs a combination of field system measurements and spatial heterogeneity analysis. Using the typical coal mining area in Shenmu, northern Shaanxi, as the research subject, it systematically investigates the soil moisture distribution characteristics influenced by various factors such as fissure types, fissure scales, topography, and soil types in subsidence areas. The results show that: ①the soil moisture content in the fissured and non-fissured areas is significantly lower than that in the control area, and the fissure type is not the main factor affecting the soil moisture content. ②In the wind-blown sand area, the influence range of large, medium and small scale fissures on the surrounding soil water is within 100 cm, 80 cm and 50 cm, respectively; in the loess area, the influence range of large, medium and small scale fissures on the surrounding soil water is within 70 cm, 50 cm and 30 cm, respectively. ③The average soil moisture content is 8.70% on the relatively exposed side and 9.20% on the relatively collapsed side of step fissures, and the difference of the influence of fissures on soil moisture is small. ④Fissures change the soil moisture content at different slope positions. The average soil moisture content within 0-100 cm of the fissures on the upper, middle, and lower slopes is 18.2%, 21.1% and 23.8%, respectively, and the soil moisture content follows the order: lower slope > middle slope > upper slope. ⑤The distribution pattern of surface soil moisture in the loess area is significantly different, while the distribution of surface soil moisture in the wind-blown sand area is unbalanced. The fissure scale and topography are the principal factors affecting the distribution of soil moisture in the coal mining subsidence area. Research on the influence of mining ground fissures on soil moisture distribution in arid and semi-arid regions can provide a theoretical basis for precise ecological restoration and vegetation configuration in mining areas.