Research On Water Quality Analysis And Evaluation And The Countermeasures Of Dongchang Lake

Water pollution has been one of the important factors to shortage of water resources. Water eutrophication is the general phenomenon of water pollution. It is also a difficult problem for water environmental pollution government at home and abroad. Urban lake eutrophication has great influence on its aquatic functions. Research of eutrophication evaluation and the countermeasures for urban lakes can provide scientific foundations for water environment protection and improvement. Research results can guide people to develop and use water resources of urban lakes effectively and reasonably, keep ecological balance, and promote the sustainable development for urban lakes. Dongchang Lake in the southwest of Liaocheng City, Shandong Province, with a total area of 4.2km~2, is the biggest urban man-made lake north of Yangtze River and the core of water system of water city in northern China. Its water eutrophication is serious because of water pollution around it.In this paper, on the basis of statistical analysis to hydrobiological monitoring data, eutrophication condition or pollution level is evaluated from three angles. The evaluation result based on the quantity of phytoplankton and biomass is that nutrient state of every lake district is eutrophication. The evaluation result based on dominant species is that nutrient state of the whole lake is eutrophication. The evaluation result based on diversity index is that pollution level of the whole lake belongs to moderate or slight pollution. Spatio-temporal analysis is carried out for water quality monitoring data. Evaluation is gained according to the criterion of general landscape water substance and the criterion of upper water environment quality. Water eutrophication conditions of three ditricts of Dongchang Lake are evaluated with fuzzy mode recognition theory and grey clustering method. The evaluation results of two methods are compared. The conclusion is that the two results are mainly identical. The causes of eutrophication of Dongchang Lake are analyzed and countermeasures are proposed. Its eco-environmental quality will be improved by means of the combination of management and control.