Water abundance assessment model development and water hazard control strategies for karst aquifers in metal mines: A case study of the Maoping lead zinc mine in Northeast Yunnan, China

To address the limitations of relying solely on borehole-specific water inflow rates to evaluate the water abundance of karst aquifers in metal mines, this study presented a comprehensive assessment in the Maoping lead-zinc mine in northeastern Yunnan, a typical deep karst mining area, using a hierarchical evaluation model for karst aquifer water abundance. This model integrated three key dimensions: seepage field characteristics (permeability coefficient, water level drawdown, and unit water inflow), aquifer characteristics (effective thickness of aquifer and water sample mineralization), and structural development characteristics (fault density and drilling fluid loss). Subjective weights for each evaluation indicator were determined using the analytic hierarchy process (AHP). using ArcGIS platform, the study area was categorized into five distinct water-richness zones based on the water abundance index (WAI) thresholds: very low water-rich area, low water-rich area, moderate water-rich area, high water-rich area, and very high water-rich area. The evaluation results demonstrate that the karst aquifer in the western wing of the Shimenkan anticline, located at the Maoping lead zinc mine in northeastern Yunnan, exhibits high overall water abundance. The karst aquifer in the axial zone of the Shimenkan anticline exhibits significant vertical zonation in water abundance, characterized by high values in the upper strata and low values in the lower strata. The water abundance of the karst aquifer in the eastern wing of the Shimenkan anticline is generally weak, and the water abundance of the shallow karst aquifer gradually weakens towards the east. The passive governance mode of “aggregate injection→filling grouting→water source blockage” was used to address the high potential water inrush disasters induced by the exposure of local strong water-rich areas in metal mines; the active governance mode of “geophysical exploration first→drilling verification→regional advanced curtain grouting” for strong water-rich aquifers in the region. This study offers critical technical guidance for optimizing deep mine layout and developing effective drainage strategies in karst metal mining regions.