Spatial-Temporal Distribution and Factors Influencing the Soil Vadose Zone Water Content in Mining-Area Grasslands

High-intensity mining of coal can seriously influence groundwater resources and the ecological environment of grasslands near the mines and in the mining areas. A soil water flow model was established using field measurements and numerical simulation based on soil water in the Baorixile open-pit mine area to elucidate the distribution characteristics and influencing factors of soil water content in grassland vadose zones in arid and semi-arid climate regions. Soil water content in the grassland area and the waste dump area of the mine were compared under different conditions by changing the soil structure and humus thickness. The soil water content in the study area was higher from April to September, but lower from October to March. After soil reconstruction, the soil water content of the waste dump area of the mine was improved at a burial depth of 0-50 cm, which was more conducive to the growth of plants. The responsiveness of the reconstructed waste dump to atmospheric precipitation and evaporation was less than that of the original grassland due to the water-blocking effect of the clay layer, which hindered the recharge of groundwater by precipitation infiltration. Humus with a thickness of 70 cm in the grassland area had better water retention, while it was 50 cm in the waste dump. These results provide a theoretical basis and technical support for sustainable development and ecological restoration in ecologically fragile areas.