Effects of groundwater level changes on soil characteristics and vegetation response in arid and semiarid coal mining areas

Coal mining in arid and semiarid regions often leads to numerous ecological and environmental problems, such as aquifer depletion, lake shrinkage, vegetation degradation, and surface desertification. The drainage from coal mining activities is a major driving force in the evolution of the groundwater-soil-vegetation system. In this study, based on hydrogeological and ecological vegetation investigations in the Bojianghaizi watershed, used mathematical statistics, linear regression, and correlation analyses to elucidate the impact of groundwater level fluctuations on soil characteristics and the response mechanism of surface vegetation in coal mining areas. The results show that there is a significant negative correlation between groundwater table (GWT) and soil water content (SWC), soil conductivity, soil organic matter (SOM), soil available nitrogen (SAN), and soil available potassium (SAK). Mining activities lead to the destruction of soil structure, which greatly weakened its ability to retain water and nutrients. The contents of SWC, SOM, and SAN in the mining area are significantly reduced, which are at least 49.73 %, 47.56 % and 59.90 % lower than those around the mining area. As the GWT increases from less than 0.5 m to 0.5-7 m, and then to more than 7 m, the vegetation type in the study area transitions from hydrophilic and halophytic species to semi-dependent groundwater species, and finally to xerophilous species. This study not only provides a scientific basis for the sustainable development and environmental protection of similar mines in the world, but also has important significance in guiding the ecological management and rational utilization of water resources in coal mine areas.