Water Quality Trend Analysis And Water Quality Evaluation In Dongjianghu Lake Basin

Dongjianghu Lake basin is located in the southeast corner of Chenzhou, Hunan province, which is an important source of drinking water for Hunan province, and is the ecological water inlet area for Xiangjiang River, also is the important strategic resource of Hunan province "Two Type of Society". The water quality of Dongjianghu Lake basin is related to tens of thousands of people’s drinking water safety. In this paper, based on the water quality sections data of the Dongjianghu Lake Basin of each quarter from the third quarter of 2011 to the second quarter of 2014,selected 8 kinds of water quality index:Dissolved oxygen (DO), biochemical oxygen demand (BODs) 5, potassium permanganate index (CODMn), chemical oxygen demand (COD), ammonia (NH3-N), total phosphorus (TP), lead (Pb), arsenic (As),analyzed the water quality change trends and spatial distribution features of concentration of water quality indicators in the basin, systematically summarized and compared 4 kinds of representative water quality evaluation methods, and analyzed the evaluation result difference and the cause,in order to provide scientific reference for regional water environmental pollution control and comprehensive management.Through analyzed the spatial distribution features of concentration of water quality indicators in the Dongjianghu Lake Basin, obtained that:the water quality of Zhe River and ChangCe River are poorer than other rivers, the water quality of Dongjianghu Lake and Ou river are better. And Zhe River and ChangCe River which belong to the exogenous type, the water pollution of Ou River comes from internal,Which belongs to the endogenous pollution.Through analyzed the water quality trend in the Dongjianghu Lake Basin,in addition to dissolved oxygen (DO)and total phosphorus(TP), the concentration of the other 6 water quality indicators showed a downward trend;dissolved oxygen concentration change trend is not obvious, the total phosphorus are slowly rising.the water quality each section presents improving trend. While Yanzipai section and Power Station of Shibi Mountain section exist Non-point source pollution.This study adopts the single factor index method、Nemero index method、 The fuzzy comprehensive evaluation method and Comprehensive water quality identification method these 4 methods to evaluate water quality of each monitoring section of the second quarter of 2014 in DongjianghuLake Basin, obtained that: comprehensive water quality identification method is much coincided with the mean value of those 4 methods.Using comprehensive water quality identification method to evaluate water quality of each monitoring section of each quarter from the third quarter of 2011 to the second quarter of 2014, From the different sections, obtained that:the comprehensive water quality identification index of Toushan section、Bailang section and XiaoDongjianghusection are lower than others,Sigong bridge section、 Laowu village andYanzipai section are higher,but reached its functional area water quality class Ⅲ water quality standards. From the quarterly change trends, obtained that:the comprehensive water quality identification index of Songshan village section and Power Station of Shibi Mountain section present moderate upward trend, other sections are moderate downward trend.