Study of Impact of Urban Nonpoint Source Pollution on River Water Quality Based on Integrated Simulation and Discussion on Corresponding Prevention Measures

Not only is the Dian Lake a water source for the people of Kunming, but also it receives the point and nonpoint source pollution load in its basin. With the control over point source pollution and the development of urbanization in recent years, nonpoint sources have become important pollution sources in the Dian Lake Basin. Therefore, this study used the InfoWorks Integrated Catchment Modeling (ICM) model to obtain the basic urban information and the parameters of urban nonpoint source pollution discharge to calculate urban nonpoint source pollution load in Kunming. The study found that the nonpoint source pollution load is linearly correlated with precipitation, and the pollution load of chemical oxygen demand (COD) is the most serious while that of total phosphorus (TP) is the lightest in Kunming. In addition, this study used a QUAL2K one-dimensional water quality model to simulate the change of pollutant concentration in the river before and after precipitation, and it was found that the pollutant concentration in the water increased by up to 8.1 times after precipitation. Based on the calculation result and the urban nonpoint pollution characteristics of Kunming, four measures were proposed to reduce urban nonpoint source pollution load, including adopting green roofs and adding drainage outlet treatment device.