Simulation And Optimization Of Rain And Flood In Northern Cities Based On SWMM Model

Since the 21st century,the speed of urbanization in China has accelerated significantly.From a macro perspective,with the advancement of urbanization,the total urban area is continuously expanding,and the urban impervious area is also gradually climbing.Most cities will appear when they encounter heavy rain.Waterlogging problem,therefore,solving the problem of urban waterlogging has become an important task of urban development.Therefore,the concept of "sponge city" was formally put forward in my country in 2012.Its purpose is to effectively store water,avoid waterlogging,transform rainwater from dangerous sources into resources,and effectively improve the urban ecological environment.Sponge city design The rain conditions(rainfall frequency and rainfall)in the southern area are significantly different from those in the northern area;the ratio of various low-impact development measures is based on the excellent cases in the "Sponge City Construction Technology Guide" as a reference,based on the southern Mostly,it is not suitable for the design of sponge cities in the north.This paper takes Baisha Island Financial Ecological Town in Shenfu New District of Liaoning as the research object,and completes the Baisha Island Financial Ecological Town through the study of its site conditions,rain conditions,and the area to which it belongs.combined with the relevant guidelines of the "Sponge City Construction Technology Guide"The land use type is divided,and from the dimensions of runoff control,technology type,layout method,economic benefit,landscape effect,etc.,five applicable LID measures are screened,and the proportion of LID measures for each type of land use in Baisha Island Financial Ecological Town is proposed.In order to guide the later rain and flood simulation.According to the factors such as the architectural distribution,topographical conditions,surface runoff flow direction of Baisha Island Financial Ecological Town,five types of node designs combined by different LID measures were completed,which provided specific images for the design scheme.The SWMM model is a dynamic rainfall-runoff simulation model that is used to simulate a single rainfall time or long-term water quantity and quality simulation in a city.In this paper,the SWMM model is used to establish the rainfall-runoff model of Baisha Island Financial Ecological Town.By simulating the overall performance of the system under different recurrence periods,the LID requirements of Baisha Island Financial Ecological Town are clarified,combined with the Baisha Island Financial Ecological Township proposed in this paper.The proportion of LID measures in the town and the principle of optimal layout are used for LID design,and the change value of runoff coefficient affected by LID is obtained.By comparing with the category Ⅱ regional indicators in the "Sponge City Construction Technical Guide",the target runoff coefficient is obtained,and the LID measure adjustment coefficient is obtained,and the final optimization is carried out on this basis.From the simulation results,it can be seen that this scheme effectively reduces the overall runoff coefficient of the system,meets the requirements of the "Sponge City Construction Technical Guide",and conforms to the climate characteristics of the northern region;optimizes the system’s water accumulation situation,so that it can achieve no torrential rain in 5 years.Water accumulation;greatly reduce the overall pollutant content of the system,effectively achieve energy saving and emission reduction.Finally,the method is summarized to form a SWMM simulation optimization method suitable for each land type,which can effectively guide the design work of the sponge city landscape.