Assessment of water inrush risk based on the groundwater modeling system—a case study in the Jiaojia Gold Mine Area, China

The Jiaojia Gold Mine area is located in the northeast of Shandong Province, Eastern China, and its hydrogeological and structural geological conditions are complex; consequently, the mining conditions are complicated. Based on the hydrogeological measured data of the Jiaojia Gold Mine area, we first analyzed its main aquifers, that is, the Quaternary pore aquifer and bedrock fracture aquifer, and the hydrogeological boundaries of the simulated area were defined. Then, after defining the boundary conditions, and generalizing the vertical structure of the aquifer, hydraulic properties of the fault zones and groundwater flow system, a conceptual numerical simulation model of the area was established using the groundwater modeling system (GMS). Finally, after space division, time discretization, setting of the initial values, partition of the hydrogeological parameters, disposal of the sources and sinks, we continuously adjusted the hydrogeological parameters to ensure that the fitting error of the long-time observation well was within the confidence interval. With these values, we used this model to study the groundwater flow field and predict the mine water inflow. Numerical simulation showed that the general direction of groundwater flow in the study area was from southeast to northwest towards the sea, and faults acted as barriers to groundwater runoff. The mine water inflow increased with increasing mining level, while the water inflow at similar mining levels tended to remain steady with increasing mining period; the seasonal variation in the water inflow was clear. A groundwater funnel was formed in the main gold mine area, in which the groundwater level would decline by 10–77 m; the funnel had a range of approximately 609–3255 m2. This model can determine the dynamic response mechanism of groundwater to multimine interferences in dewatering and drainage, which provides a foundation for mine water control and water resource evaluation.