Analysis and Evaluation of Water Quality Improvement of the Main Pollution Rivers of the Nansi Lake Basin

The water quality of the Nansi Lake basin has gained particular attention on account of the construction of the East Route in the South-to-North Water Transfer Project.This article makes a comparative analysis of the effect of the five years' water quality improvement of the main polluted rivers in the Nansi Lake basin,according to the water quality monitoring data of the main polluted rivers in Nansi Lake basin in 2005 and 2010.The result shows that,compared with 2005,the decline rate of the average concentration of CODCr,NH3-N,TP,TN is in order 54.9%,85.1%,46.3%,45.7% in 2010,the decline rate of total average concentration is 58.0% and the total average value of the average composite pollution index declines from 11.4 to 4.0.As a result,the water quality of the main polluted rivers in Nansi Lake basin has got significant improvement.The single pollution average share rate of CODCr,NH3-N,TP,TN is in turn 12.1%,11.0%,11.9%,65.0% and TN is the primary pollutant in the basin.CODCr and NH3-N are close to Class Ⅴ water quality of GB 3838—2002 overall and the overall mean value of DO reaches 12.48 mg/L,realizing the goal of Rivers have water,and water has fish initially.It is advisable to further strengthen the control of the pollution source,pay attention to the control and management of the non-point pollution sources and comprehensively tackle the main polluted rivers and the main pollutants pertinently.