Study On Layout Planning Of LID Facilities In Sponge City Based On Urban Stormwater Simulation

At present,China’s urbanization process is accelerating,resulting in significant changes in the underlying surface conditions.The increase in the area of the impervious underwater surface has caused a significant increase in surface runoff,which has affected the water delivery capacity of the urban drainage pipe network system and caused urban flooding The odds are greatly increased.In order to better manage the urban waterlogging problem,my country has proposed the concept of sponge city construction,which is mainly achieved through the Low Impact Development(LID)approach.How to scientifically plan the layout of LID facilities is the key to the construction of sponge cities.Therefore,the thesis takes Xiushan sponge city construction area as the research object,and it is of great academic significance and application value to carry out LID facility planning research based on urban rain and flood simulation.Using the coupling of SWMM and MATLAB interface program,the automatic calibration technology of SWMM model parameters is studied.Based on the comparative analysis of urban rain and flood reduction effects,a single LID facility is analyzed.Finally,through the construction and solution of a multi-objective optimization model,the LID facility planning of the research area is proposed.Layout plan.The main research conclusions are as follows:(1)Through the secondary development and research of the SWMM model,the interface program between SWMM and MATLAB is established,the SWMM calculation engine is called on the MATLAB platform,and the automatic calibration process of the model parameters is realized using the BP neural network method.The NS value is as high as 0.856.The error between the simulated results of the SWMM model and the measured data after automatic calibration is controlled within 5%.(2)Summarize the structure,scope of application,advantages,disadvantages and construction costs of common LID facilities such as green roofs,rainwater gardens,biological retention zones,grass planting ditches,permeable pavements,submerged green spaces,and constructed wetlands.A comparative analysis of LID facilities is made in terms of control objectives,economy and landscape effects.(3)The simulation results of the rain and flood control effects of the individual LID facilities show that under different rainfall recurrence periods(P = 1a,2a,10 a,and 50a),the effect of the same scale LID facilities on the total runoff control: rain garden>Permeable pavement> green roof> grass ditch;on the effect of peak runoff control:rainwater garden> permeable pavement> green roof> grass ditch;on peak current time control: rainwater garden> grass ditch> green roof,permeable pavement.(4)A multi-objective optimization model for LID facility planning and layout of Xiushan sponge city based on SWMM simulation was established,and the model was solved using NSGA-Ⅱ algorithm combined with SWMM,and a solution set of LID facility layout optimization scheme was proposed.The AHP was used to evaluate the five groups of plans,and the LID optimal layout plan was obtained.The proportions of each LID were green roof,rain garden,permeable pavement and grass ditch layout proportions of 0%,8.85%,26.34% and 0.44%,the total runoff control rate is77.3%,the peak runoff reduction rate is 64.2%,and the peak delay time is 14 min.