The Evaluation And Comparison Of The Space Distribution Water Quality And Comparative Analysis Of Water Environmental Features In Nansi Lake

The East-Route of the South-to-North Water Diversion Project is a large-scaleinfrastructure project that will solve the problem of a serious shortage of water in thenorth of China. Nansi Lake is an important water transfer channel of the East-Rout ofthe South-to-North Water Diversion Project that is the largest lake in the northern partof China. The first-stage project of the Eastern Route of South-to-North WaterTransfer launched in due form in the year of2013. The water quality of Nansi Lakemust reache Ⅲ class of the “Surface Water Quality Standard”(GB3838-2002) in theend of2012, and the water quality improvement of Nansi Lake is a concern. Since2000, Shandong Province carried out a serious pollution control measures such assmall watershed comprehensive pollution control strategy of the “govern, use,protect”, the water quality of Nansi Lake has been greatly improved. The situation ofNansi Lake water quality improvement can be fully understood by the scientificevaluation of water quality and eutrophication status and water environmental featuresanalysis in Nansi Lake.In this paper, comprehensive water quality identification index was determinedby using many menthods for water quality and eutrophication status to be analyzed.The paper used the space distribution water quality monitoring data to evaluate thewater quality and eutrophication status in Nansi Lake. The water environmentalquality features of the Nansi Lake Basin were analyzed at temporal and spatial scaleand by selecting heavy polluted rivers. Through a series of resrarch and analysis, thefollowing conclusions can be drawn.(1) Comprehensive water quality identifation index is suitable for evaluating thewater quality and eutrophication status in Nansi Lake Basin because of its simplecalculation, intuitive results and reasonable evalution.(2) The overall water quality improved by one to two grades as the water qualityidentification index of water quality indicators in the inflow rivers of Nansi Lake wasdecreased during the period from2010to2011, compared with the values during the period from2006to2007.(3) Compared with water quality during the period from2006to2007, the waterquality of Nansi Lake was improved, and the proportion of comprehensive waterquality reached the requirement of water environment functional zone was increased25.6%during the period2010to2010. There was no water quality inferior to class Ⅴduring the period2010to2011. The water quality of the upper lake was better thanthat of the lower lake and the water quality of Xiaobei Lake and Nanyang Lake waspoor.(4) According to the eutrophication evaluation results of Nansi Lake bycomprehensive water quality identification index, the level of eutrophication of NansiLake water ensemble average was light in the four years of monitoring.(5) In Nansi Lake Basin the reduction ratio of CODCrand NH3-N were74.4%and93.1%in2010compared with that in2000at the monitoring sections. Five-yearaverage showed downward trend. The water quality of the rivers had been greatlyimproved, but average CODCrwas not reached the water quality Ⅲ standards. Thewater quality of the monitoring sections showed a certain intra-annual variationbecause of the effects of the hydrology, non-point source pollution and point sourcepollution.(6) The distribution of water pollution in Nansi Lake Basin had obvious features.The water quality of control units in the west of Nansi Lake basin was better thanthose in the east of Nansi Lake basin. The control units of Guangfu River and LaoyunRiver in Jining were the most seriously polluted areas.(7) Accoring to the monitoring data of Nansi Lake Basin in the year of2000and2010, the rivers of worse water quality and the rivers of better water quality wereselected by the CODCrand NH3-N. The rivers of worse water quality of CODCrweremainly distributed in the east of the lake.The evaluation of water quality and eutrophication status based oncomprehensive water quality identification index method and analysis of waterenvironmental quality festures in Nansi Lake Basin provided a greatly scientificdecision for Nansi Lake in the East-Route of the South-to-North Water Diversion Project and management of water quality environment in Nansi Lake Basin, and havegreatly theoretical and practical significance.