Mechanisms of Water Chemical Evolution and Multi-dimensional Assessment of Suitability for Reuse in Mine Water from Arid Regions

• Assessing the suitability of groundwater reuse in underground mines through multiple methodologies • Analysing the hydrochemical characteristics and spatiotemporal evolution of water in arid regions • Na⁺, K⁺ and Cl⁻ are the primary contributors to groundwater salinisation • Unsuitable for direct irrigation; establishing a multi-scale research framework Gaining a thorough understanding of the hydrochemical characteristics of mine water in arid regions and evaluating its potential for wastewater reuse is of great significance for protecting groundwater, increasing water supply and optimising the water supply structure. This study focuses on the groundwater reservoir cluster at the Xingmei Coal Mine in Xinjiang. Based on 44 sets of samples collected from inflow and outflow points between 2020 and 2024, a comprehensive approach combining the ion ratio method, fuzzy comprehensive evaluation and irrigation suitability assessment was employed to reveal the hydrochemical characteristics and evolutionary mechanisms of the mine water, and to evaluate its suitability for reuse. The results indicate that mine water in the study area is generally neutral to slightly alkaline, with a pH ranging from 7.22 to 8.98 and a TDS ranging from 2467.73 to 3706.56 mg/L; the mean TDS of outflow is higher than that of inflow, suggesting that the groundwater reservoirs have a limited mitigating effect on salinity. The predominant hydrochemical type is the Cl·SO₄-Na·K type. EWQI results indicate that the groundwater reservoir exerts a certain moderating effect on some parameters. The irrigation suitability assessment shows that the samples are predominantly classified as Wilcox Class V, with irrigation reuse subject to dual constraints of salinity and sodicity. Consequently, this study proposes and adopts a multi-dimensional evaluation framework, using end-point requirements as the objective function to identify key limiting factors and implement targeted management strategies.