基于SOM和 PCA的闽江流域地表水水质综合评价

根据2014年1月至2015年11月闽江流域19个断面的水质月均值监测数据,采用自组织特征映射网络(SOM)和主成分分析(PCA)法研究了闽江流域水质时空变化特征,并用水质指数对闽江水质进行了综合评价。SOM分析将水质样本分为3个空间群组,其中水质变化周期分2个阶段:4—11月、12月至次年3月。PCA法分析表明,春冬季沙溪和富屯溪支流以及闽江下游福州城区河段营养盐水平偏高,在春夏季上游部分河段和下游闽江口有机污染水平偏高。水质指数评价结果显示,闽江流域整体水质较好,其中三大子流域及闽江下游水质评价从优至劣顺序为:富屯溪流域、建溪流域、沙溪流域、闽江下游流域。

Comprehensive evaluation of surface water quality in Minjiang River Basin based on SOM and PCA

Based on the monthly average monitoring data of water quality from 19 sections in the Minjiang River Basin during the period from January 2014 to November 2015, we used the self-organizing map(SOM)and principal component analysis(PCA)to study the characteristics of temporal-spatial variations of water quality in the Minjiang River Basin, and conducted a comprehensive assessment of water quality of the Minjiang River with the water quality indices. Through the SOM analysis, we classified the water samples into three space groups, in which the water quality variation period was divided into two phases: one from April to November, and the other from December to March of the following year. The PCA analysis shows that the nutrients in the tributaries of the Shaxi and Futunxi rivers and in the urban river section in Fuzhou City downstream the Minjiang River maintained at a high level in the spring and winter. Meanwhile, the organic pollution level was high in some parts of the upper reaches and the downstream Minjiang River mouth in the spring and summer. The results of evaluation of water quality indices show that the water quality in the Minjiang River Basin is good on the whole. The three sub-basins and the lower reaches of the Minjiang River showed a descending order in water quality as follows: the Futunxi Basin, the Jianxi Basin, the Shaxi Basin, and the lower reaches of the Minjiang River Basin.