干旱区水环境质量评价的模糊数学法——以石羊河流域武威市为例

本文简要概述了进行水环境质量综合评价的必要性及评价原则 ,在分析总结目前常用的几种评价方法的基础上 ,提出模糊数学法的科学合理性。模糊数学法采用隶属函数来描述水质的分界 ,实行隶属度择近原则 ,体现了实际界限的模糊性 ,使评价结果更接近客观实际 ;权重的大小是根据实测值确定的 ,超标越多 ,权重越大 ;模型考虑了各项参数在总体污染中的作用差异 ,最终结果不仅能够反映出此水体的水质级别 ,还能反映出该水体对应于各级水质的隶属情况。因此 ,用模糊数学法来评价水质更能反映水体实际情况 ,是一种较好的水质评价方法。经用此方法对石羊河流域武威市水环境质量进行综合评价 ,结果得出石羊河干流校东桥、扎子沟及红崖山水库水中COD、BOD、NH3-N及粪大肠菌群等指标严重超标 ,都属于Ⅴ类水 ;上游黄羊水库、南营水库及西营水库水质整体较好 ,都属于Ⅰ类水 ,但BOD含量较高。

Fuzzy Mathematics Method for Water Environmental Quality Assessment in Arid Area —Taking the Wuwei City as an Example in Shiyang River

This paper summed up the necessity of carrying on comprehensive assessment to water environmental quality and the principle of assessment briefly. On the basis of analysing several methods of assessment at present, put forward the rationality of fuzzy mathematics method. It adopted function of subjection to describe the boundary of water quality, was under the jurisdiction of subjection degree selecting nearly principles, reflect the mistiness, make the result closer the objective reality; The weight was definedingaccord to the survey value, the more exceed standard, the greater the weight was; Model considered every parameter's difference in overall to pollute, final result could reflect not only the rank of water quality, but also the subjection situation of every rank. So, the fuzzy mathematics method could reflect the actual conditions of water body, it was a kind of better method for water quality assessment. Took this model for comprehensive assessment in Wuwei city, Shiyang river valley,and got the results the mainstream of Shiyang river water quality were the worst, belong to gradeⅤ, many indexs exceed standard seriously, such as COD, BOD, NH 3-N and the dung intestine fungus group, etc. However, the Huangyang reservoir, Nanying reservoir and Xiying reservoir water quality were better, belong to gradeⅠ, but BOD content was relatively high.