Parameter Analysis And Optimization Research Of Typical LID Facilities

With the deepening of the urbanization process in my country,the natural surface with high water permeability and low runoff coefficient has been transformed into construction land with low water permeability and high runoff coefficient,causing damage to the hydrological environment in urban areas and causing a series of natural disasters.In order to solve this problem,my country proposes to use low impact development(LID)technology to build a sponge city,absorb and utilize most of the rainfall on the spot,and solve the problem from the source.By investigating the research status at home and abroad,it is found that some scholars have studied the parameters of LID facilities,but there are few studies on the parameters of LID facilities under different rain patterns and rain intensities.As the main source of urban runoff,rainfall is also a hydrological The most important input parameters in the hydrodynamic model simulation,play an important role in the simulation study.Combined with different types of rainfall data,the sensitivity analysis of LID facility parameters can effectively identify various performance parameters in the early stage of sponge city construction,provide a reference for the optimization and adjustment of LID facility parameters,and predict and evaluate the performance of construction results..This paper takes the waterlogging-prone area in a campus in Hunan Province as the research object,and uses the SWMM(Storm Water Management Model)software to establish the underlying surface and pipe network system model.Combined with 7kinds of typical natural rainfall data during the local flood season and the simulated rainfall data of Chicago rain pattern under 4 kinds of return periods,through the modified Morris screening method,the total outflow,peak flow,total runoff,and peak runoff are used as the targets for green roof,permeable Parameter sensitivity analysis was carried out for three typical LID facilities such as pavement and rain garden.The optimal performance parameters and optimal design methods of LID facilities are presented.The sensitive parameters in the green roof are soil porosity and soil hydraulic conductivity;the sensitive parameters in the permeable pavement parameters are the porosity of the pavement layer,the water seepage rate of the pavement layer,the porosity of the aquifer,and the water seepage rate of the aquifer;rainwater Sensitivity parameters in the garden are soil porosity,soil hydraulic conductivity.Under the same rainfall conditions,the LID facility parameter sensitivity was negatively correlated with the rainfall return period,and the rain peak coefficient was positively correlated with the parameter sensitivity under the condition of similar total rainfall.The optimization suggestions for LID facilities are as follows: green roofs should use high porosity and high water permeability materials as their matrix layers when the roof load meets the design conditions,which can effectively control rainwater runoff;permeable pavement should ensure its structural strength.High water permeability and high porosity materials are used as pavement layers,and the aquifer materials should use materials with strong water storage performance and moderate water permeability,which can effectively control surface runoff and slow down the arrival time of flood peaks;rain gardens should focus on increasing soil permeability.and soil porosity to ensure its water storage capacity.