Evaluation Method of Water Quality Based on Set Pair Analysis with Varying Coefficient of Discrepancy Degree

In order to manage water quality effectively, it is necessary to develop a comprehensive evaluation of water quality. Set pair analysis (SPA) is a new theory of quantitative analysis for certain and uncertain questions, and discrepancy degree coefficient “i” in connection degree formula is uncertain. For water quality evaluation, the value of discrepancy coefficient i plays an important role in set pair analysis. In this paper, a new effective method to the determination of discrepancy degree coefficient i is suggested. This result is coherent to the real condition and in conformity with that of the grey correlation method. It validates that the new model is feasible in synthetic evaluation of the water quality.