The improve SPA method research and its application in water environment assessment

The previous SPA study only focused on three ranks evaluation. This paper presents an improved SPA method utilizing original relation degree malleability of SPA, and extends it to five ranks evaluation. The improved method can depict identity, discrepancy and contrary in more detail. In addition, this study combines fuzzy comprehensive evaluation method to evaluate six main factors of surface water environment, instead of the discussion of i⁺,i^-, j⁺, j^- coefficient. It not only obtains evaluation result but also obtains probability distribution of each rank. In this paper, we apply the method to the comprehensive assessment of Tuojiang water quality and compare the results with Gray relation method, gray cluster method. We conclude that the improved SPA method can represent the true state of the object with extensive engineering application value.