Research On SWMM Data Modeling Based On Fine Division Method Of Subcatchment And Pipeline Network Optimization And Transformation Scheme

With the rapid development of economic construction and urbanization construction,high-intensity rainstorms have gradually increased,the proportion of urban imperviousness has increased,and the design standards of drainage systems in some areas of the city are low or aging.In many cities at home and abroad,waterlogging disasters occur frequently,which seriously affects the urban residents’life production and industrial and agricultural production.Therefore,it is of great research significance to study the regional rainfall and runoff laws and the drainage capacity of the pipe network.Using computer technology to establish an accurate urban storm water model can simulate the rainfall and runoff process and the confluence process in the urban research area and help to evaluate the city’s flood control capabilities and improve the city’s stormwater management mechanism.Suqian is a well-known"flood corridor"in China.In recent years,it has suffered many major waterlogging disasters.The government of Suqian attaches great importance to the prevention and treatment of urban waterlogging disasters.In this paper,22km~2 in Sucheng District of Suqian is taken as a research area,and a data modeling method that comprehensively considers factors such as land use and underground pipe network layout is proposed.Then the fine division method of subcatchment is explored to achieve the construction of high-precision SWMM,and SWMM are used to conduct research on simulation and empirical research,and determination of pipeline network system transformation plans.The research results are as follows:(1)In view of the problem of waterlogging disasters in Sucheng district,this paper explores the problems of determining the number of the starting and ending node of the pipe section in the modeling of the drainage system and the flow direction of the single pipe section according to the flow direction of the pipe section group based on the DOM,DEM and data of pipe network system in study area and then completes the pre-processing work of the pipeline network modeling data by independently writing code to change the data table and determine the pipeline network generalization plan;using the Tissen polygon method to complete the subcatchment division and introduces the significance of the parameters of the nodes,pipelines and the subcatchments in the SWMM modeling process and the tools and calculation methods used for parameter calculation;completing the SWMM data modeling based on Arc GIS after parameter calibration.(2)According to the existing problems of the established swmm,based on the commonly used division methods of subcatchment at home and abroad,subcatchment division influencing factors,and graph theory knowledge,a fine division method of subcatchment is proposed;using the simulated results of measured rainfall data to compare the accuracy of the two sets of SWMMs constructed by the fine division method of subcatchment and the Tissen multi-deformation methodusing and then analyze the sensitivity of each hydrologic and hydrodynamic parameters under different rainfall conditions and different underlying surface conditions and perform a sensitivity analysis on the swmm of the selected area and the parameter calibration.The research results show that the fine division method of subcatchment has a higher accuracy of swmm;under different rainfall conditions and different underlying surface conditions,the runoff coefficient and runoff peak are highly sensitive to the roughness coefficient of the impervious area and the water storage parameters of the depressions and these two parameters should be adjusted first during the calibration process.(3)Based on the established swmm,the Chicago rain pattern method is used to design four rainfalls with a recurrence period of 1 year,5 years,10 years,and 20 years,respectively simulating the proportion and number of pipe fullness and node overflow in the pipe network system.Then the reasons for the lack of drainage capacity are analyzed.The results of the study indicate that the drainage capacity of the pipeline is severely restricted under a 10-year period and and greater intensity of rainfall.The analysis results are consistent with the design standards of the pipe network;the reasons of insufficient drainage capacity in research area include greater rainfall intensity and frequency,and unreasonable pipe network laying,etc.,and some pipe network systems need to be modified to reduce submergence losses.(4)This paper analyzes the characteristics of the problem pipe section identify the bottleneck pipe section based on the simulation results of the swmm under the rain conditions of 1 year,5 years,10 years,and 20 years,then proposes a modification plan and analyzes the properties of the rainwater well and pipe section.The results show that:expanding the diameter of the pipe section is more effective than changing the slope of the pipe section and increasing the depth of the pipe to improve the drainage capacity of the pipe network.It is proposed that the optimal design of the rainwater storage tank in the pipe network,and combined with the DE algorithm,complete the optimal position and the parameters of the rainwater storage tank.The research results of setting a single rainwater storage tank show that:setting the downstream of the node with the most serious overflow has the best effect.After adding appropriate rainwater storage tanks,the reduction of the overload time of each pipe section compared to the original simulated overload time is better than the effect of increasing the pipe diameter by 60%.