Influences of water diversion from Yangtze River to Taihu Lake on water quality of Taihu Lake between 2007 and 2008

On the basis of pilot studies on the water diversion from the Yangtze River to Taihu Lake(WDYT),the influence of WDYT both on the water supply crisis in Wuxi City in 2007 and from January to June in 2008 were analyzed systematically.During the one-week water supply crisis in Wuxi City,water quality indexes such as dissolved oxygen and ammonia in water sources of the Gonghu water supply plant improved from category V to category Ⅲ when the WDYT went into operation.According to the national water quality standard,the water quality of the Gonghu water supply plant and the Xidong water supply plant also gradually improved.WDYT was in operation in the second half of 2007 and the first half of 2008.The concentration of the permanganate index,the total phosphorous,and the total nitrogen in Gonghu decreased from 7.04 mg/L,0.106 mg/L,and 4.10 mg/L in May 2007 to 3.35 mg/L,0.087 mg/L,and 2.87 mg/L,respectively,in the same period of 2008.The concentration of ammonia nitrogen held the water in category Ⅲ.The results showed that WDYT was very important to the improvement of the water quality in part of the area and to guaranteeing water supply in Taihu Lake.Countermeasures to advancing long-term operation of WDYT were finally promoted in the paper.