Research on the influence of diversion flow ratio on the water environment in Nanjing

In this paper, we take the Qinhuai River Basin in Nanjing as an example to study the influence of diversion flow ratio on the water environment. The daily precipitation of 20 rainfall stations in the basin was collected from 1962 to 2006, and the rainfall under different assurance rates was calculated by P-III frequency curve to calculate the surface runoff in different typical years. In the meantime, according to the downstream furcated estuary water level in different typical years, the diversion flow ratio under different frequencies was calculated by using a mathematical model of the water environment. The results show that the diversion flow ratio of a branch channel increases with the increase of water level difference, and the growth rate decreases gradually. The other branch channel diversion flow ratio decreases with the increase of water level difference, and the decreasing rate decreases gradually. The pollutant concentrations in the bifurcated rivers are equal, but the concentration decreases exponentially with the increase of the upstream flow. Under different rainfall frequencies, the diversion pollutant ratio and diversion flow ratio are equal in different months of different years. doi: 10.2166/ws.2019.120 s://iwaponline.com/ws/article-pdf/doi/10.2166/ws.2019.120/604767/ws2019120.pdf Weiwei Song Yong Pang (corresponding author) Key Laboratory of Integrated Regulation and Resource Development on Shallow Lakes, Ministry of Education, College of Environment, Hohai University, Nanjing 210098, China E-mail: ypang@hhu.edu.cn Weiwei Song College of Hydrology and Water Resources, Hohai University, Nanjing 210098, China and College of Engineering, University of Miami, Coral Gables, Florida 33146, USA