Impacts of Underground Reservoir Site Selection and Water Storage on the Groundwater Flow System in a Mining Area—A Case Study of Daliuta Mine

The natural ecological conditions in the Shendong mining area in China are very fragile, and water resources are seriously lacking. As the production scale of the Shendong mine continues to expand, the demand for water for production and living is also increasing; however, the available surface and underground water is decreasing, and the water scarcity in the Shendong mine is becoming increasingly apparent. Obtaining water resources is a major technological challenge for green mining. The underground reservoir is a new type of underground water conservancy project, and the water shortage in China’s coal mine pits is resolved by underground reservoirs, which also makes a substantial contribution to the effective utilization of water resources. How the construction of underground reservoirs affects the groundwater system in a mining area has become one of the most important factors to consider when finding sites for underground reservoirs. In this study, we took the Daliuta Coal Mine as an example. A numerical model based on the hydrogeological conditions in the mining area was developed to determine the effects on groundwater using FEFLOW software via the finite element method. The model was used to analyze the impacts of coal seam mining thickness, overlying lithology, water-storage range and the water level of the underground reservoir on the groundwater flow system in the mining area. The results indicate that the thickness of the coal seam mining and the lithology of the overlying reservoir both had a significant effect on the upper aquifer system. The water-storage range and water level of the underground reservoirs were the main influences on the lower aquifer system. The results prove that underground reservoir storage had a good effect on water retention in the groundwater system in the mining area, and was able to achieve the desired result of storing groundwater and reducing water loss. It also had a positive feedback effect on the mining area’s environment.