河流水质评价中模糊数学评价法的应用与比较

选择2005年6个典型日（1月12日、3月10目、5月10日、7月13日、9月8日和11月10日）的水质，运用两种模糊数学评价法对浙江西苕溪流域港口断面的水质进行评价并作比较。第一种数学评价法采用较为简单的单因素模糊综合评价法，另一种采用多级模糊数学评价法。评价结果表明，1月12日、3月10日和11月10日的水质达到国家Ⅰ类水质标准；而5月10目的水质相对最差。比较两种评价方法，单因素模糊综合评价法对单个因素的影响敏感，特别是超标值对最后的相对隶属度贡献大；而多级模糊评价法综合各个因素来评价现状水质，因而反映出水质的综合情况。结合港口断面的特点分析水质变差的原因，结论是：流域农业劳作带来的面源污染物质进入港口断面使得该断面在农作高峰期水质较差；同时，断面的水资源短缺问题较为严重，导致水环境容量较小，污染物较难稀释扩散。

Application and Comparison of Fuzzy Mathematical Methods in the Assessment of River Water Quality

In this paper, the water qualities at the section of harbors in Xitiaoxi River of Zhejiang province were assessed and compared with two fuzzy mathematic methods. The sampling dates were selected on 6 representative days in 2005, i. e. , January 12, March 10, May 10, July 13, September 8 and November 10. The first method was single factor fuzzy synthesis assessment method and the second one was multilevel fuzzy assessment method. The results showed that the quality of water sampled on Januaryl2, March 10 and November 10 reached the grade I of water standard, while that on May 10 was the worst relatively. By comparison of the results obtained by the two methods, the single factor fuzzy assessment method was more sensitive to single factor, especially the factors exceeding the water standard greatly contributed to the final relative degree of membership. Contrastively the second method integrated all factors to assess the water quality to reflect the overall water conditions. Considering the characteristics of the section of harbors, it was concluded that the worsening the water quality sourced from agricultural non-point pollution. On the other hand, the shortage of water resources resulted in small water capacity, sequentially the difficulties of dilution and diffusion of the pollutants.