Evaluation of mine water inflow quality based on multiple methods

To reduce the negative impact of mine water gushing on the environment, it is necessary to evaluate the water quality. Taking the Pingdingshan coalfield as the research object, six components – namely, chroma, turbidity, total dissolved solids, total hardness, chloride (Cl⁻) and sulfate (SO₄ ²⁻) – were selected as index factors. The composite weight was calculated using the variable-weight theory, and the water quality of mine gushing water was evaluated using the matter-element extension model, fuzzy variable set model, Bayesian theory and Nemerow index method. The deviation of the four evaluation methods was calculated based on the specially constructed mathematical model. The research results show that the order of the deviation of the evaluation method from small to large is as follows: fuzzy variable set method (5.5) < matter-element extension method (8) < Bayesian statistical method (10) < Nemerow index method (17). The fuzzy variable set method is more suitable for Pingdingshan coalfield mine gushing water quality assessment. The authors hope that this research can provide a certain reference value for the evaluation of mine water quality in the future.