Abstract: Accurate evaluation of the quality of water environment is an important prerequisite for the utilization and protection of water resources. A hybrid model of water quality evaluation is proposed based on entropy weight method and partial order set evaluation to divide evaluation levels and determine evaluation indices according to classification criteria. According to the Hasse diagram obtained from Hasse matrix, the ratings of water quality is acquired by analyzing the hierarchical information presented by the Hasse diagram. The model is used to evaluate the water quality of nine monitoring points in the mainstream of the Yangtze River and Jialing River. Results demonstrate the accuracy of the present model. It is applicable to water quality evaluation as it overcomes the dependence on sample scale in entropy weight method and meanwhile solves the dispute over subjective weighting in conventional evaluation methods.

Key words: water quality assessment, partial order set, entropy weight method, empowerment dispute, Hasse diagram