Acid mine drainage control in mining areas: identification of groundwater recharge pathways and source reduction strategies

This study aims to address the critical challenge of the formation of acid mine drainage (AMD) in coal mining areas by systematically investigating groundwater recharge pathways and developing targeted source reduction strategies. A range of methods were employed, including field investigations, surveying and mapping, in situ measurements of hydraulically conductive fracture zones (HCFZs), spatial and hydrological analyses, yielding multi-source data. Based on the comprehensive dataset obtained, a novel methodology was developed to identify surface water infiltration pathways. Downhole video monitoring results indicate that the advancements in coal mining technology have gradually increased the heights of HCFZs. Furthermore, mining-induced fissures in hard rock layers were found to extend further vertically and form dense, interconnected networks, leading to higher permeability coefficients compared to those in weak rock layers. Surface water preferentially infiltrates at intersections of HCFZs, coal seams, and topographic features. Notably, groundwater recharge in the goaves of the No. 10 coal seam primarily occurs along the paleo-valley system where natural drainage aligns with mining-induced fissures. This study provides an example of source reduction treatment for AMD in mining areas.