Evaluation on spatiaotemporal variations of mine water quality and water source identification based on key dominant factors in loess hilly and gully region

It is difficult to accurately identify the sources of water inrush between sandstone-mudstone interbedded overburden in loess hilly and gully region, and these proportions of different water sources cannot be quantified. For this reason. Based on the systematic collection of surface water and groundwater samples from Zhujiamao Coal Mine in northern Shaanxi. This study revealed the hydrochemical evolution laws of water quality and the recharge relationship of various aquifer systems by mathematical statistics, Piper (trilinear) diagram, Gibbs diagram and the conventional hydrochemical characteristic method. Meanwhile, this study analyzed the evolution characteristics of stable isotopic composition in water, clarified the spatial and temporal variations of water quality from various sources under different environmental background. On this basis, this study constructed a calculation model for the mixing ratio of water inrush sources based on the T-spherical fuzzy power aggregation operators coupling with TOPSIS method, rough set theory, D-S evidence theory (DSET) and single-index unascertained measurement functions by using conventional and isotopic characteristic ratios as the indexes. In this study area result shows that,both of surface and groundwater are of the main hydrochemical type of Na-SO₄·Cl, but their controlled factors vary greatly. Specifically, the hydrochemical compositions of surface water are jointly controlled by the weathering of silicate rock and evaporative crystallization, while the hydrochemical compositions of groundwater are mainly controlled by evaporative crystallization. In addition, the surface water subjected to strong evaporation recharges the groundwater to some extent. The T-TOPSIS-RST-DSET-SIUMF discrimination model for the mixing ratio of water inrush sources shows that over 50% of water inrush in Zhujiamao Coal Mine in northern Shaanxi comes from the roof sandstone water and the surface Shakonggou water, which accuracy is verified by three dimensional high-density resistivity method.