Water inrush risk evaluation in a complex water-rich deposit based on AHP−TOPSIS method

To accurately assess the water inrush risk of the KOLWEZI copper−cobalt mine in the Democratic Republic of the Congo, we established a risk assessment index system based on the hydrogeological conditions of the mine. The system includes 6 quantitative indicators selected from 3 aspects: geological structure characteristics, aquifer hydrogeological characteristics, and the spatial relationship between the mining area and surface water bodies. These indicators are proportion of fault filling sandpaper, fault scale, unit water yield, permeability coefficient, horizontal distance, and vertical distance. The analytic hierarchy process（AHP） was used to determine the weights of these indicators, and the technique for order of preference by similarity to ideal solution（TOPSIS） was employed for a multi-factor comprehensive evaluation of the water inrush risk in the mining area. The results show that the water inrush risk index for the fractured zone of the F₂ fault in the western part of the open pit is 0.17（danger zone）, while the index for the F₃ fault area in the southeastern part is 0.87（relatively dangerous zone）, which aligns with the exposed hydrogeological characteristics. The study indicates that the AHP−TOPSIS model effectively integrates both subjective and objective weights, enhancing the scientific validity and reliability of the evaluation results. This provides a theoretical basis for water prevention and control efforts in similar mining operations.