A hybrid model integrated variable fuzzy set theory and set pair analysis for water quality assessment in Huai River Basin

Water quality assessment is a multi-attribute fuzzy decision problem including steps of evaluation index selection, weight assignment and fuzzy analysis. The maximum membership degree principle used in fuzzy analysis has an obvious defect of information loss, which may lead to a deflection of result. In order to avoid this problem, the maximum connection degree principle (MCD) proposed from set pair analysis theory is first adopted to develop an improved fuzzy set model. The proposed model (VF-MCD) is applied to assess the water quality of Huai River Basin in China. Result reveals that 86% water body of Huai River Basin is clean or slightly polluted and 14% is heavily polluted. Compared with traditional methods, the proposed model in this study could identify the degree of water pollution relatively reliably and correctly.