Modeling of Water Inflow Zones in a Swedish Open-Pit Mine with ModelMuse and MODFLOW

The Aitik mine is Sweden’s largest open-pit sulfide mine and Europe’s most important producer of gold, silver, and copper. However, the mine faces problems related to water inflow, particularly in the northern zone and western hanging wall sections of the pit, resulting from various mining activities, including blasting, loading, and hauling. The presence of fracture zones within the pit further exacerbates the issue, as continuous mining operations have aggravated the thickness of these fractures, potentially increasing the volume of water inflow. Consequently, this could lead to various geotechnical issues such as slope collapse, and increase the possibility of acid mine drainage formation. This research develops a numerical model using ModelMuse as the graphical user interface and MODFLOW to simulate groundwater flow in the mining pit under different scenarios, by considering the absence, presence, and varying thickness of fracture zones to address the issue. By analyzing these scenarios, the model estimates the volume of water inflow into the pit under steady-state conditions. The results indicate that the presence of a fracture zone plays a crucial role in controlling water inflows by significantly influencing the inflow budget—by 90% for the north shear inflow (NSI) and by 20% for the western hanging wall inflow (WHWI) at deeper depths of the pit. Variations in the fracture zone thickness result in a 15% increase in water inflow at deeper depths of the pit. These findings provide valuable insights for improving mine water management strategies and informing sustainable mine closure planning to mitigate long-term environmental risks.