Simulation Study On Stormwater Control Of Different Lid Models In Park Green Space Of Qingbaijiang District Based On Swmm Model

This study is aimed at the problem of rainfall runoff reduction in urban parks under the traditional design and development.Based on the “Yihu Park Sponge City Demonstration Project” in Qingbaijiang District of Chengdu,the rainfall runoff model of the research area in the northwest of Yihu Park was constructed by the Urban Stormwater Management Model(SWMM)software,combined with the research area runoff coefficient and the research area.The actual situation of the mat surface is laid out in the low impact development(LID)mode.The regression analysis method and the marginal utility diminishing law are used to study the change trend of the rainfall runoff reduction rate of the single model LID under different areas,and select the reasonable marginal utility interval.The LID mode combination provides a reference when selecting the layout area to avoid blind design combinations.On this basis,the design of different LID combination modes and the optimization of corresponding schemes are carried out.Research and analysis under the goal of meeting the requirements of park greenbelt runoff coefficient,explore the optimization of different LID combination modes,which help to maintain and improve the park’s service function,and provide some reference for engineering practice.The results show that different LID play an important role in the stormwater control in parks.Through the combination of three LID modes: permeable pavement,sunken green land and green roof,the runoff coefficient will be less than 0.2 from the traditional development under the different rainstorm return period,which is in line with the design requirements of the park greenbelt runoff coefficient.Through the regression analysis of runoff reduction rate under different LID layout areas,combined with the marginal utility diminishing law,the percentage of reasonable layout area of three LID measures in obtaining optimal stormwater control effect is obtained: green roof 50%~70%,lower The sinking green space is 70%~90% and the permeable paving is 66%~95%.Selecting the corresponding LID layout area percentage in a reasonable value range for LID combination can achieve better stormwater control effect and achieve ideal economic benefits.At the same time,through a comparative analysis of different LID combination schemes,a set of economic optimization combination schemes is obtained: 74% permeable pavement + 90% sinking green space + 50% green roof;At the same time,get a set of optimized area combination plan: 95% permeable pavement + 70% sinking green + 50% green roof,in order to provide a certain reference for engineering practice.