灰色聚类法综合评价滴水湖水系环境质量

Synthetical evaluation of water quality of Dishui Lake water system by gray clustering method

将滴水湖水系看作一个灰色系统进行研究,利用灰色聚类理论,以地表水环境标准和富营养化分级标准为基础建立灰类评价体系,确定聚类指标的隶属度和标准灰类的权重,得到各聚类指标对标准灰类的聚类系数,最大聚类系数关联的等级即水体质量等级。2010年,每2周1次对滴水湖水系11个监测点的溶解氧(DO)、化学需氧量(CODMn)、五日生化需氧量(BOD5)、总磷(TP)、总氮(TN)、氨氮(NH3-N)、透明度(SD)及叶绿素a(Chl.a)进行监测,取各指标的年均值,建立灰类评价系统。结果表明:滴水湖水源大治河及引水干道随塘河处水质属于Ⅳ类～Ⅴ类,呈富营养化和极度富营养化状态;闸外引水河芦潮引河段水质类型为Ⅲ类,为富营养化水平;闸内引水河道水质总体呈现富营养化状态,水质类型为Ⅲ类;滴水湖湖区水体质量良好,水质类型为Ⅲ类,呈中营养水平。

Dishui Lake water system was considered to be a gray system in this paper and the gray clustering theory was adopted to evaluate its water quality by building an evaluation system with reference to the given evaluation standards,the environmental quality standards for surface water and the classification standard for eutrophication level.The clustering coefficients were obtained after calculating the values of grade of clustering indices and weights of gray standards.Water quality grade was determined according to the maximum clustering coefficient.Water samples were collected from 11 monitoring stations in Dishui Lake in 2010 and water quality parameters were measured including DO,CODMn,BOD5,TP,TN,NH3-N,SD and Chl.a.The average values were used in evaluating the water quality.The results indicated that water qualities of Dazhihe river,which was the source of Dishui Lake,and Suitanghe river near the source belonged to grade Ⅳ toⅤ and reached eutrophic and extremely eutrophic levels,respectively.Water quality in rivers before and after the sluice belonged to grade Ⅲ and reached the eutrophic level while water quality in the lake was in grade Ⅲand at the mesotrophic level.