综合指数法和模糊综合法在地下水质量评价中的对比--以遵义市为例

Comparison of comprehensive index method and fuzzy comprehensive method in the evaluation of groundwater quality:A case study in Zunyi City

综合指数法和模糊综合评价法在地下水质量评价中被广泛应用。岩溶地区地下水环境脆弱,潜在污染来源复杂。为了更好地了解综合指数法和模糊综合法在岩溶地下水评价中的应用效果,本文以贵州省遵义市为例,利用这两种方法分别对该市具有代表性的9个地下水点水质进行评价和对比分析。结果显示:遵义市浅层地下水水质总体较好,Ⅲ类及Ⅲ类以上水占33%,但个别区域地下水水质很差,主要为NO-2、NH+4、Mn、Na+、Cl-、SO2-4、溶解性总固体、总硬度(CaCO3)和Se等超标;两种方法评价结果一致的共有6个水点,均属Ⅱ类水质,结果不一致的3个水点,在综合指数法中全为Ⅳ类水,而在模糊综合评价中则是Ⅲ类水1个,Ⅴ类水两个。出现差异的主要原因是综合指数法在综合分值计算中过于强调单项指标最大值的作用和未考虑参评指标的权重,而模糊综合法则很好地克服了这些不足,精细地刻画出指标值对水质分级界限的接近程度并量化了所有指标对地下水水质的影响权重。可见,地下水水质评价中,模糊综合法要明显优于综合指数法。

The comprehensive index method and the fuzzy comprehensive method are widely used in groundw-ater quality evaluation.The groundwater environment in karst area is vulnerable and the potential pollution sources are complex.In order to better understand the effect of comprehensive index method and fuzzy com-prehensive method in assessment of karst groundwater in Zunyi City,Guizhou Province,a typical karst area was selected for study.Applying comprehensive index method and fuzzy comprehensive method to evaluate and contrast analysis groundwater quality of nine representative water points in Zunyi,the results showed：The shallow groundwater quality in Zunyi is generally good,33 % of the water was grade III or higher;but the individual regional groundwater quality is poor,mainly the NO-2 ,NH＋4 ,Mn,Na＋,Cl-,SO2-4 ,total dissolved solids,total hardness （CaCO3 ）and Se exceeded the standard.There were six water points whose evaluation results were the same and all were grade II.The remaining three water points were different;in the comprehensive index method all were grade IV,while in the fuzzy comprehensive 2 water points were grade V and one water point was grade III.The main reasons for these differences are the maximum value of the single index are emphasized when calculate the comprehensive value F and the weight of evaluation inde-xes are not taken into account in the comprehensive index method;however,these disadvantages of the com-prehensive index method are resolved in the fuzzy comprehensive method,the proximity of indexes to water quality classification limitation is carefully depicted,and the impact weight of all indexes to groundwater quality are quantified visible,so in the groundwater quality evaluation,the fuzzy comprehensive method is superior to the comprehensive index method.