Research On Water Quality Of Nansi Lake And The Inflowing Rivers

Nansi Lake is important as it is a regulating lake, convergence of the north andsouth and the online lake in the East Route of the South-to-North Water DiversionProject. However, as the lack of protection of the environment in recent years, Nansihas a series of water safety issues to become one of the important factors restrictingthe local socio-economic development, and a major obstacle to the construction of theouth-to-North Water Diversion Project, threatening the ecological environment.Therefore, understanding of the degree of contamination of the Nansi Lake and theevaluation of the Lake and the water quality of the inflow river are a certain guidingsignificance to water pollution control of Nansi Lake.Combined with the actual situation, this study selects5water quality monitoringpoints in the lake and15major inflow rivers as objects of study, and evaluates waterquality of Nansi Lake basin using Nemerow index method, fuzzy evaluation, graycorrelation evaluation method, cluster analysis, principal component analysis. Theresults of water quality evaluation of Nansi Lake basin is analysised, pollution causesand prevention measures are also investigated. The main contents are as follows:(1) The results of the5water quality monitoring points in Nansi Lake are had acomprehensive water quality evaluation. Results show that: the Nansi Lake can bedivided into two groups, the first group consists of Nanyang, Dushan, which haveserious pollution; the other group consists of Zhaoyang, Weishan, which have lessserious pollution than first group. The lake is mainly organic pollution, eutrophicationserious.(2)15major inflow rivers are selected to have a comprehensive water qualityevaluation of its pollution levels. The results show that:15rivers can be divided intothree groups, the first group consists of Guangfu, Peiyan, Laoyun, which have themost serious pollution as have high load of CODcr, CODMnand BOD5and seriousorganic pollution. The pollution level of the second group where surrounding livingand industrial area with the similar pollution factors, is weaker than the first group,have poor water quality conditions. The third group consists of Xuechengsha, Xinxue,Xuechengxiaosha, which have lighter pollution. The serious polluted rivers in group1and2, are mainly distributed around the Shangji lake.(3) The number of the rivers flowing into Nansi Lake decreases gradually fromnorth to south, and the pollution degree of the rivers also gradually decreases whilethe water quality condition gradually increases. The pollution load that was importedinto Nansi Lake was mostly concentrated in the Nanyang and Dushan Lakes. SinceNansi Lake is one of the lakes in east line of South-to-North water project, it isnecessary to control the pollution of Nansi Lake as well as perfect the collaborativescheduling management between inflowing rivers and Nansi Lake, so that the waterquality of inflowing rivers during the water diversion can be improved.