Simulation Research On The Effectiveness Of Urban Rainfall Runoff Pollution Control

With the gradual deepening of point source control in China,the impact of rainfall runoff pollution on the quality of natural water bodies has become more prominent.How to effectively control rainfall runoff pollution has become one of the main research directions of sponge city construction.The thesis mainly studies the differences in the collection types and construction processes of the elements of the non-point source pollution load model under the conditions of different scales of the study area,and cooperates with the rainfall monitoring data to analyze the cumulative erosion law of typical underlying runoff pollutants in large-scale watersheds.Secondly,it also explored the help of the small-scale water quality and water quantity model in analyzing the expected effects of sponge construction in industrial factories and improvement measures,and explored the mechanism of sponge city combination measures on peak shaving and pollutant reduction.Based on the experience of Shenzhen sponge city construction,the paper analyzes the generation and erosion of typical underlying surface runoff pollution in large-scale watersheds,the cumulative change law of runoff pollution,and the change process of pollutant erosion concentration with urban rainfall and runoff pollution as the core.A non-point source pollution load model for the watershed.Taking the construction of a sponge city in an industrial plant in Shenzhen as an example,through the application of the non-point source pollution load model at a small scale,the actual application effect of the sponge construction in the industrial plant,the annual total runoff control rate and the pollutants under the combined measures of the sponge city were simulated and evaluated Reduce efficiency,reduce peak and stagnate effects,and make rational suggestions for the effectiveness of combined measures and pollutant control methods.The main conclusions of the study are as follows:(1)By analyzing the cumulative relationship between total runoff and pollutant load,when rainfall is around 10 mm,the erosion load of surface runoff pollutants on a typical underlying surface increases approximately linearly with the accumulation of runoff;it increases with rainfall intensity The greater the initial erosion of pollutant load in surface runoff,the more significant is SS> TP> COD> ammonia nitrogen.(2)Under the design rainfall conditions with different rainfall intensities in typical zonings,with the increase of rainfall intensity,the maximum concentration of pollutants in the runoff of rainwater continues to increase.As the rainfall intensity increases,the initial scouring effect also increases,and the peak concentration is advanced,but the decline occurs faster after reaching the maximum concentration.(3)Study the long-term simulation by constructing the source pollution load model at a small scale and using 10-year continuous rainfall data from 2008 to 2017,comparing the effectiveness of the traditional development model and sponge city combination measures.The simulation results show that the 10-year continuous rainfall model The annual average runoff control rate of the combined sponge city measures is64.7%,which basically meets the target of 65% annual total runoff control rate,and the peak reduction efficiency of the combined facilities of the sponge city will gradually decrease as rainfall increases;and runoff The corresponding reduction rate of runoff pollutants is about 50%,which is basically the same as the results of other sponge city pilot city industrial parks,meets the control goals,and at the same time proposes suggestions for the improvement of the pollution control capacity in the later plant.(4)Observing the peak flow change curve,it can be found that the effect of peak stagnation under small rainfall in the combined sponge mode is more obvious.Comparing the sponge combined mode with the pure gray mode,it can be found that the peak shaving effect in the sponge combined mode has basically met the pressure reduction goal of the pipe network,and the stagnation and stagnation effect of the simple gray facility can be achieved under fewer rainwater collection ponds.In addition,it can be found that with the increase of design rainfall from 69 mm to 94 mm,the peak shaving lag in the sponge combination mode is not as stable as the gray facility,but it is more stable,and it has achieved its desired effect;the peak shaving lag in the simple gray mode The change of flow rate before and after the peak is too obvious,which is not conducive to the stable management of the plant network and the efficient use of pipes and channels.