The Comprehensive Ecological Evaluation Research In Upper-reach Lake S Of Lake Nansi

Lake Nansi is the storage lakes of East Route of South to North Water Diversion Project, and it’s always the storage lake of drinking water, so, its water quality is directly related to the economic and social sustainable development and water ecological environment improvement in Jining, Zaozhuang and the region along East Route of South to North Water Diversion Project. Lake Nansi is long and narrow from north to south, there are many rivers into the lake, especially the upper-lakes. The living garbage that is along the urban residents is easy access to Lake Nansi, therefore, Lake Nansi is the most important point of controlling pollution. If Lake Nansi’s water ecological status changes can be understood, it has important significance for the management and sustainable developmentof Nansi Lake’s surrounding regions.The reseach contents and methods in this paper are as follows:Firstly, building the lake’s water ecological principles and methods of the evaluation system were explored, and the theoretical basis was provided for the establishment of evaluation index system of lake water ecological status. Secondly, the evaluation model of lake water ecological status was built, and according to the evaluation purpose and data, the upper-lakes of lake Nansi’s ecological status evaluation indexes were chosen; and four criteria for the ecological assessment of lake were proposed, they were water quantity, water quality, eutrophication and aquatic life; and on the basis of the improved normalization method, the comprehensive evaluation method of water ecology was established, that was, the variable weight comprehensive evaluation method of water ecology, thirdly, according to the different characteristics of water quantity, water quality, eutrophication and aquatic life, the corresponding evaluation methods were used respectively to get scores of each rule layer in order to achieve the effect of quantitative evaluation of lake water ecological situation, and among them, the comprehensive evaluation of water quality used the principal component analysis method, and the detailed causes of water pollution was analysed, in addition to the effects of river water into the lake, the water transfer of South to North Water Diversion East Route Project, and flood of the rivers into the lake can make the flow rate increase that the sediment disturbance leads to the water pollution; forthly, the analysis of hydrological time series analysis method was applied to the water quality index sequence, the water quality index’s composition of Wangmiao monitoring point and other five monitoring points of Nansi Lake were analysed detailedly, so as to make a reasonable change of water quality change trend analysis; finally, according to the evaluation results of each criterion layer, the lakes’ water ecological status was evaluated and assigned points, and this provided the technical support for the research of lake water ecological status evaluation system.In this paper, the lake water ecological status evaluation was with the evaluation of upper-lakes of lake Nansi as an example. The water ecological status change and regularity of the upper-lakes of lake Nansi in 2008-2014 were researched, and the change rule of water quality indicator sequences in each water monitoring points were studied, then it was concluded that the water ecological status of the lake nansi was good. In this paper, according to the problems that were found in the process of upper-lakes of lake Nansi’s water ecological research, the corresponding suggestions were put forward.