Simulation And Evaluation Of The Drainage Ststem In Suqian Based On SWMM

This paper aims to research drainage system of Maling River district, Suqian. SWMM is selected as the research model by summarizing domestic and international research status of drainage system. Applying the data management tool and spatial analysis tool of ArcGIS, the division of subcatchment area is researched. Based on the collection, collation and analysis of the local network information, the network is generalized. According to measured data, the parameter calibration work is completed and the drainage system model of Maling River district in Suqian is constructed. Using the constructed model, the hydraulic and water quality simulation of the local drainage system is completed. The conclusions is as follows:(1) The principle of SWMM was analyzed and researched, and the input parameters of SWMM was clarified. Combined with data management tool and spatial analysis tool of ArcGIS to obtain the required data, the workload is greatly reduced in the course of establishing the model. According to measured data, the parameter calibration work was completed. Based on rainfall designed by Chicago hydrograph model, the hydraulic and water quality simulation of the local drainage system is conducted.(2) The relationship of rainfall, infiltration and runoff in the research district under different rainfall intensity is analyzed. The runoff has a strong correlation with the rainfall intensity, the greater the rainfall intensity, runoff is higher. Under the condition of different rainfall intensity, the runoff peak flow of the system is 3.6m3/s,30.4m3/s, 71.8m3/s,112.9m3/s,169.9m3/s,213.4m3/s,257.3m3/s. The arrival time of the runoff peak flow has a 9-14min delay than the arrival time of rainfall peak flow. The ponding time and ponding depth of the network system is also analyzed.(3) The washout of the pollutant in the research district under different rainfall intensity was analyzed, total non-point pollutants increased with the increase of the rainfall intensity. The emission of pollutants reached a peak after 45-50min late than the beginning of the rainfall. The four pollutants emissioned into the river reflect obvious first flush effect.(4) Through the optimization of pipe and pipe dredging, the ponding problem of the system is solved, the improved system basically has no ponding problem under 2-year return period rainfall. This can guide the design of the drainage system. Through setting reasonable storage unit to solve non-point source pollution. Simulation results showed that storage unit can reduce more than 90% of the runoff peak flow and more than 90% of the pollution load caused by the initial runoff.