Research On Non-point Source Pollution Reduction Measures Of City River In Suzhou

With the increase of urban development and population,irrational human activities have exacerbated the non-point source pollution of water bodies, the NPS pollution is a assignable cause of the river in Suzhou. The dynamic factor of the NPS pollution is precipitation process, the carrier of pollutant is rainfall runoff, so, Urban rainwater runoff pollution is the main component of the NPS pollution. By taking some effective stormwater runoff control measures, we want to seek some feasible countermeasures to reduce NPS pollution, then,the measures can improve the river quality conditions in the study area.Firstly, we do the rainfall runoff pollution research of the Guandu river area of Suzhou, according to the terrain, the route of rainwater drainage district and other characteristics of the study area, the generalization on the catchment area, water wells and pipelines have been completed, secondly the SWMM model of study area has been done, at last, the reasonable runoff model, the surface pollutant accumulation and erosion model and the street sweeping modelshas been established.Depending on the type of land use we set up four kinds of LID control measures,through stormwater runoff simulations for different return periods of rainfall and different combinations of LID control measures, we get various rainwater outlet water quality data and analyze the water quality changes of different combinations of Lid control measures. It showed that the greater the measure covers, the more obvious the regulation effect in surface runoff control, pollution peak and total pollution control.Through in-depth study of the Delft3D model, the river in Guandu area issimulated.According to river's hydrological characteristics, topography, river boundaries,the initial conditions and boundary conditionsmodeled experimentally, we improved the model of study river. At the beginning,the river hydrodynamic simulations performed to obtain the hydraulic fluid state.We import the data of water quantity and quality by simulation of SWMM model through the pollution port of Delft3D model, then the change of water quality for the study area stormwater outlet into the river has been simulated. We analyzed the condition of water quality changes in study area through inputting the bestcombined control measures data in 3 different rainfall return period.By linking SWMM model and Delft3D model,we finished a complete and effective simulation of the entire rainfall effect to the water quality of study river. By adopting the best LID control measures for the rain water quality control, it improve the effect ofrainfall to receive river water quality, we achieve the assessment to river water quality through the analyze to water quality data, it has certain theoretical and use value to practical engineering.