Analysis And Evaluation On Water Quality For Main Inflow Rivers Of Nansihu Lake

Nansihu Lake is an important water source in Shandong Province, and it is also a major regulation and storage hub of South to North Water Transfer Project. Since the 1980's, water quality of Nansihu Lake has been gradually deteriorated, which has a close relationship to the pollution of a large number inflow rivers. Therefore, understanding the pollution degree and water quality status of inflow rivers, and making a reasonable prediction of future water quality have some significance for water pollution treatment of Nansihu Lake.In this paper, according to actual situation, some of the major inflow rivers were selected to make an analysis of water quality status. Water quality and eutrophication were evaluated, and water quality of the next three years of Dongyu River were predicted. The content of this paper follows:(1) According to water quality monitoring results of inflow rivers, this paper selected comprehensive water quality identification index to make single factor evaluation and comprehensive water quality evaluation of monitoring sections, and evaluation results were analyzed. It showed that the comprehensive water quality improved year by year on the whole, pollution of Chengguo River, Laoyun River and Guangfu River was serious, and quality of Dongyu River and Si River was better.(2) According to characteristics of eutrophication, this paper evaluated eutrophication of inflow rivers. The result showed that Guangfu River, Chengguo River and Zhuzhaoxin River were in the state of eutrophication, nutritional status of Si River and Dongyu River were in the better state.(3) Combined with water quality monitoring datas, this paper selected GM (1,1) model based on grey theory and its improved model to make a reasonable prediction of monitoring indicators of Dongyu River. This prediction had a certain theoretical value.(4) Based on water quality evaluation and prediction of inflow rivers of Nansihu Lake, pollution reasons and control countermeasures for Nansihu Lake basin were presented in this paper such as governance of inflow rivers, strengthening non-point source pollution control, the full restoration of ecosystem functions and formulation of regulations.