Research And Evaluation Of LID Facility Layout In Urban Reconstruction Based On SWMM Model

With the development of urbanization,the types of urban underlying surface are constantly changing,and the frequency of extreme weather is also increasing,which can easily lead to flood disaster events in cities,causing harm to human beings in society,economy etc.To prevent extreme flooding in the old residential areas,this paper took the sponge city construction as the center,the old residential areas of Huainan city as the research object,to construct of the SWMM model,by adding the LID facility,designed 11 kinds of LID facility combination schemes,and studied the water quality and quantity of different layout areas of individual LID facilities and 11 kinds of LID facility combination schemes.At the same time,in order to better compare and evaluate different schemes,the life cycle cost calculation method was introduced.The evaluation indexes of runoff,flood peak discharge the solid suspended pollutants and the life cycle cost were evaluated by subjective and objective weighting method,and multi-objective analysis of different design schemes was carried out by using Technique for Order Preference by Similarity to an Ideal Solution method(TOPSIS).The main research contents and conclusions are as follows:(1)Studing the reduction effect and regular of individual LID facilities on water quality and quantity.The proportion of green roof has a linear relationship with the reduction rate of runoff,peak discharge and Total suspended solids.The scale proportion of permeable pavement has a linear relationship with runoff reduction,pollutant reduction and runoff reduction,and has a nonlinear relationship with flood peak discharge reduction rate.The relationship between biological retention facilities and the vegetable swales and runoff reduction,flood peak discharge reduction and pollutant reduction is nonlinear.For different LID facilities,the reduction degree of runoff,flood peak discharge and the total suspended solids varies with the change of rainfall return period.(2)11 combination schemes were designed to study the reduction effects and regulars of various combination schemes on water quality and quantity.The results shows that all scenarios have a reduction effect on water quality and quantity,but with the increase of rainfall return period,the reduction effect gradually weakens.The TOPSIS was used for multi-objective analysis.For the comprehensive evaluation of the four indicators,the relative proximity of the 11 schemes is:S2>S4>S8>S10>S3>S11>S6>S5>S9>S1>S7.(3)For single LID facilities,at the same layout area,the relative proximity is expressed as: the vegetable swales > permeable pavement > green roof(The biological retention facilities allow a small layout range,so no comparison),the vegetable swales performance effect is the best.However,when the green roof is laid together with the vegetable swales or permeable pavement,the relative proximity is higher than the combination of the two LID facilities of permeable pavement and the vegetable swales.When the area of LID is 31 percent,the relative proximity degree is generally low.(4)S8 and S5 schemes,when the scale of LID facilities is different,the relative proximity of S8 is significantly higher than that of S5,indicating that at the same LID facilities,the layout area is the key factor to determine the reduction effect of water quality and quantity.Figure [42] Table [25] Reference [81]...