Study On The Simulation Research Of Water Quality Influence Base On Discharge Mode Of Water Sediment Two-phase Model

Origin of life is water,which is basis of human’s survival and development.With the improvement of people’s living production level and the process of urbanization continues to accelerate of late years,pollution of water resources is becoming more and more serious,a series of water quality issues are also increasingly become the focus of discussion and research. This paper based on water sediment two-phase model,through the study of the water quality under different discharge modes in water area of the Yangtze River,to reveal the pollutant migration and diffusion rule in different discharge modes of the water area of the Yangtze River.This paper base on Delft3 D software,establish hydrodynamic model,and coupling with water sediment two-phase water quality model,in order to get the suitable hydrodynamic—water sediment two-phase water quality couping model for this paper,and then simulate the main water quality parameters variety in different discharge mode of Yangtze River waters. This paper focuses on the migration and diffusion rule of COD,total nitrogen and ammonia nitrogen,the research conclusions are as follows:Within the scope of the entire simulation of the flow field,whether it is single point source discharge mode,or two point source discharge mode,in the simulation of the flow field in the area of the river,the diffusion and migration of pollutants concentration decreased gradually along the flow direction,width direction along the river pollution in the vicinity of the center point of diffusion is also getting lower and lower,meanwhile the concentration of dissolved oxygen in water gradually increased with the decrease of the concentration of pollutants. Owing to fluid as the carrier of pollutants migrate along the flow direction gradually from upstream flow field to downstream flow field,so upstream part pollutants(COD、total nitrogen and ammonia nitrogen)diffusion distribution tends to be stable in 30 minutes,downstream part tends to be fully stable after 60 minutes.In order to optimize discharge mode,this paper selected six monitoring points throughout the grid coordinate system to monitor the changes of water quality,from the monitoring results found,whether COD concentration,total nitrogen concentration or ammonia nitrogen concentration,only a monitoring point in upstream part and a monitoring point in downstream part appeared in the case of part-time two point source pollutant concentration higher than single point source pollutant concentration. Overall,single point source discharge mode impacts on water quality is still greater than two point source discharge mode. Thus indicating that compare with two point source discharge mode and single point source discharge mode,two point source discharge mode is able to reduce the concentration of pollutants in most flow field regions,lead to concentration of pollutants is not too concentrated,in order to avoid the high concentration pollutants in large regions,meanwhile also reduce the low dissolved oxygen region in the river,comparing with two point source discharge mode and single point source discharge mode,the former effect on water quality has a significant advantage than the later,the degree of impact on the environment is relatively small,so the two point source discharge mode is better than single point source discharge mode.The research content of this paper is to support the development of Yangtze River water environment,research has very important practical significance and use value.