The Impact Study On Urban Storm Non-point Source Pollution

The study on the generation and the transportation of the rainfall runoff and the pollution of the runoff is of importance to prevention and cure the urban flooding and control the water pollution in urban areas. Based on urban storm runoff mathematical model, the impact of different rainfall and landuse on nonpoint source pollution load is discussed.Firstly, based on reference review, the advance in the study of the urban surface runoff pollution is described in chapter one, including the characteristic, type, and source of the urban storm runoff pollution . And then the control strategy of urban storm runoff is discussed. Finally, the study on urban storm water modeling is described.Secondly, the mathematical modeling of the urban storm runoff pollution is discussed, including the urban surface runoff model and the the urban drainage system model. The model give a detail description of the generation and transportation of urban surface runoff, the build-up and wash-off of the pollutant in urban surface, and the transferring of the flow and the pollutant.Thirdly, the non-steady flow hydraulics model is applied to simulate the process of the rainfall and the runoff in Taihuadao, Hanyang, Wuhan City. The modeling give a reasonable explanation to the generation of the runoff and the pollution in urban area, with the most error is no more than 20%.Based on the model the urban surface runoff pollution model, with different storm, the urban surface runoff pollution load is computerd, including SS, TP, TN and COD. And then the impact of rainfal on the urban surface runoff pollution load is analised. And the result is that, the urban nonpoint source pollution load has no significant difference when the total precipitation is equal. With the increase of the precipitation, the nonpoint source pollution load increases at some extent. At the same precipitation, the first flush peak concentration increase with the increse the rainfall intensity.Based on the urban surface runoff pollution model, with different landuse, the urban surface runoff pollution load is analysed, including SS, TP, TN and COD. And then the impact of landuse on the urban surface runoff pollution load is analised. Andthe result is that the urban nonpoint source pollution load has significant difference when different landuse is concerned. When the grassland area and undeveloped area increase 13%, 28%, and the industrial area decreases 30%, the pollution load of SS, TP, TN and COD decrease 21.6%, 23.2%, 23.1%, 22.3 %. And when the grassland area decreases 12%, the industrial area and the residential area increase 8%, 8%, the pollution loadofSS,TP,TN and COD increase 35.8%, 38.6%, 41%, 36.3%.