Potential hydraulic connectivity of coal mine aquifers based on statistical analysis of hydrogeochemistry

Mining activities interfere with the natural groundwater chemical environment, which may lead to hydrogeochemical changes of aquifers and mine water inrush disasters. This study analyzed the hydrochemical compositions of 80 water samples in three aquifers and developed a water source identification model to explore the control factors and potential hydraulic connection of groundwater chemistry in a coal mine. The results showed that the hydrochemical types of the three aquifers were different. The main hydrochemical compositions of the loose-layer, coal-bearing, and limestone aquifers were HCO₃·Cl–Na, SO₄·HCO₃–Na, and SO₄–Na·Ca, respectively. The correlation, Unmix, and factor analyses showed that the hydrochemical composition of groundwater was controlled by the dissolution of soluble minerals (such as calcite, dolomite, gypsum, and halite) and the weathering of silicate minerals. The factor score plot combined with Q-mode cluster analysis demonstrated no remarkable hydraulic connection among the three aquifers in the study area. The water source identification model effectively identified the source of inrush water. Moreover, the mixing ratio model rationally quantified the contributions of the three aquifers to inrush water.