改进的模糊层次分析法在南苕溪临安段水质评价中的应用

Application of an improved fuzzy analytic hierarchy process in water quality evaluation of the South Tiaoxi River,Lin'an Section

南苕溪是太湖的源头水系,其水质状况对杭嘉湖平原居民饮用水安全和太湖流域的污染治理有重要意义.为了了解南苕溪的水质状况,在临安段开展了2年的水质监测,分别在2009年7月、10月和2010年1月、4月采集了水样并进行水质评价.同时,为了克服以往模糊层次分析法存在的低估污染的严重性及不能评价劣Ⅴ类水质的缺点,建立了一个改进的模糊层次分析法来评价南苕溪临安段的水质,改进的模糊层次分析法以各级水质标准上、下限的中间值为限值,来计算隶属度.最后,本研究选取TN、TP、NH4+-N、CODCr和DO为评价指标,用改进的模糊层次分析法,研究了南苕溪临安段水质时空变化规律.结果表明,TN是主要的污染物,它的权重达到0.487;改进的模糊层次分析法可以得到6个隶属函数,更符合实际问题的要求.

The south Tiaoxi river is the headwater of Tai Lake.The watershed of the Tiaoxi river covers the Taihu Lake region including the Hang-Jia-Hu plain,therefore the water quality condition of this river basin has a direct effect on the health of residents in this region,and water pollution control of the headwater is of great importance in preventing Tai Lake from contamination.A two-year water monitoring project was carried out in the Lin＇an section of the South Tiaoxi river to evaluate the water quality.Water samples were collected in July 2009,October 2009,January 2010 and April 2010.In the present study,an improved fuzzy analytic hierarchy process（FAHP） was established to meet the practical water quality sitiuation and the severity of pollution up to the inferior Ⅴ water quality was successfully estimated.The improved FAHP used the intermediate value of the upper and lower limits of water quality standards as a limited value to compute the degree of membership and six membership functions were obtained.In this study,TN,TP,NH＋4-N,CODCr and DO were selected as the main contamination factors.The evaluation results showed that the major pollutant was nitrogen,with a weighted coefficient of 0.487.