Hydrogeochemical Characteristics and Water Quality Assessment of the Carboniferous Shanxi Formation Sandstone Water in the Huafeng Coal Mine Using an Integrated GTCWM-FCE-TOPSIS Framework.

Groundwater in coal mining areas is extensively extracted to prevent coal roof water inrush, generating substantial volumes of mine water that must be properly managed and treated. Accurate hydrochemical assessment is therefore crucial for developing effective strategies for water resource protection and utilization. This study proposes an integrated groundwater quality assessment framework that synergistically combines the game theory combinatorial weighting method (GTCWM) with fuzzy comprehensive evaluation (FCE) and Order Preference by Similarity to an Ideal Solution (TOPSIS). Within this framework, GTCWM reconciles subjective weights derived from the analytic hierarchy process (AHP) with objective weights from the entropy weight method (EWM) through game theory optimization, providing a balanced weighting strategy for subsequent evaluation. FCE is then applied to classify water quality into discrete categories, while TOPSIS enables refined ranking of samples within the same quality class, thereby complementing the classification with finer differentiation. The framework was applied to assess the Carboniferous Shanxi Formation sandstone aquifer in the Huafeng coal mine. Results reveal severe groundwater quality degradation, with all samples exceeding Class V standards for TDS and 77.3% exceeding Class V for total hardness (TH). Na