Research On The Design Of Low Impact Development Facilities In Urban Park Based On SWMM Simulation

In recent years,the process of urbanization in China has been accelerating.The frequent occurrence of urban rainstorm,the pollution of water environment and the massive loss of rainwater resources have become the key problems restricting the sustainable development of cities.Based on this,the Chinese government proposes a comprehensive water governance model of "sponge city",in which the construction of "low impact development(LID)rainwater system" is the focus of sponge city construction,which can not only effectively alleviate the urban rain and flood disasters caused by urbanization,but also make full use of rainwater resources to control urban non-point source pollution.In the current situation of urban construction land shortage,the value of green space of urban park has been highlighted and become an important carrier of low impact development and construction.This paper reviews the domestic and foreign low impact development theory and related research literature,expounds the formation and control process of rainwater runoff in urban parks,and takes Qianhai Stone Park in Shenzhen as a case study to study the design and Simulation of low impact development facilities in urban parks.The specific results of this study are as follows:Firstly,the runoff formation process in urban parks is divided into three stages: surface runoff generation,surface confluence and pipe network confluence.According to the spatial relationship of runoff formation,the runoff control stage is divided into three stages,i.e.source,middle and end.Based on this,eight kinds of lid facilities and corresponding applicable conditions are proposed.Secondly,based on the principle of "representativeness,high quality and stability",Qianhai Stone Park in Shenzhen is chosen as the research site.Based on the investigation and research of current situation,this paper expounds the hydrological analysis method and corresponding principle of Arc GIS.The digital elevation model of Qianhai Stone Park is the data source,and analyzes the specific characteristics of Qianhai Stone Park in four aspects of runoff direction,source area,midway area and end area,which provides corresponding suggestions for understanding the runoff formation process and the subsequent scenario design of lid facilities.Thirdly,the SWMM conceptual model of Qianhai Stone Park is studied and constructed,and four lid facilities combination scenarios are designed,including pre development mode,traditional development mode,source control mode,source control + end regulation and storage mode.Through the SWMM simulation calculation method,the regulation effect of each scenario in water quantity and water quality is analyzed.On the whole,the source control + end regulation and storage mode can be regarded as the optimal design scheme.When combined with biological detention facilities and dry pond two kinds of lid facilities,the control effect of runoff peak value and pollutant load is improved,and higher than any single type of facilities.Through the above research results,this paper hopes to provide theoretical support for the application of lid in urban park design.On the basis of satisfying the main functions of recreation and beautification of environment,the urban park takes on important ecological functions.