Experimental Study On Attenuation Law Of Pollutants And Its Application In Song Yuan River

The pollution of water quality in the Song Yuan river basin is serious,and COD and ammonia nitrogen are over standard.In this paper,the attenuation law of pollutants is studied by simulating flume of water ecological environment.The influence of inflow flow intensity on the attenuation law of pollutants is analyzed,and the attenuation coefficient of pollutants is calculated.Because the water environment of Songyuan River Basin is complex,this paper sets up a variety of scenarios to calculate the water environment capacity of Songyuan River Basin,in order to provide reference for policy makers to take targeted measures.Firstly,the attenuation law of pollutants was tested in a simulated flume of water ecological environment,and the influence of inflow flow intensity on the attenuation law of pollutants was analyzed,and the attenuation coefficient of pollutants was calculated.The experimental results show that the intensity of inflow has a significant impact on COD and ammonia nitrogen attenuation.The greater the intensity of inflow,the greater the degradation rate of pollutants and the greater the attenuation coefficient.Secondly,the allowable inflow and reduction of COD and ammonia nitrogen in Songyuan River basin under the most unfavorable scenario were calculated by using the flume experiment results.The results show that the reduction rate of COD and ammonia nitrogen is higher in Jiaoling County,but lower in other schemes.The reduction rate of COD and ammonia nitrogen is higher in Meixian County.Then,considering the influence of small hydropower,the permissible inflow and reduction of pollutants in Songyuan River basin are calculated under the condition of annual average discharge and 90% guaranteed discharge.The calculation results show that the permissible inflow of COD and ammonia nitrogen is much lower than that of non-hydropower stations under the condition of multi-year average flow and 90% guaranteed flow.Finally,under the condition of the lowest monthly hydrological discharge and the average annual discharge,the influence of different water quality of Songyuan River on the water quality of Penglai section is analyzed.The results show that the water quality of Penglai section is more affected by the discharge in dry season than by the average discharge in many years.