The Simulation Of Urban Road Design And Its Impact On Rainfall And Runoff Under LID

Under the dual impact of climate change and human activities,urban waterlogging is becoming more and more serious,and traditional road design needs to be modified to adapt to the changes that have occurred.On the basis of systematically sorting out the basic theories of low-impact development and rain-flood control,taking an east-west road in Xi’an as the research object,the road LID of the research area was proposed based on the typical measures of LID by analyzing the current status and reconstruction needs of the research area.Reconstruction plan,designed the road LID rainwater system in the study area;using the SWMM model,for multiple scenarios set,analyzed the precipitation runoff process before and after the urban road LID under different scenarios,compared and analyzed the effect of LID participation before and after runoff control The effect of Hongfeng’s reduction has clarified the impact of low-impact development urban roads on the rainfall-runoff process,which can provide a reference for the design of low-impact development urban roads.The main research results achieved in this paper are as follows:(1)Summarize the comprehensive basic theory of low-impact development and stormwater control.The traditional urban road construction method and rainwater system are expounded from the aspects of traditional urban road rainwater and flood control methods;based on the concept and technology of sponge city,low impact development concept and technology,and sponge city road LID requirements,the low impact development city is summarized Basic theory of road rain and flood control.From the SWMM model overview,model structure function,model calculation principle and model construction process,the application of SWMM model in low-impact development and stormwater control is outlined.(2)Designed a low impact development urban road rainwater system.By sorting out seven typical measures for low-impact development of urban roads,the rainwater system for low-impact development urban roads is designed from three aspects:design content,design path and runoff control method.According to the rainfall flow,select the appropriate rain type,combined with the site conditions,determine the type and size of rainwater infiltration drainage system,rainwater retention system and rainwater drainage system,and put forward different control methods for different rainwater runoff.Based on an example of the construction of a road in the east-west direction of Xi’an,the status quo of the road and the needs for reconstruction are analyzed,the layout of low-impact development measures is designed for it,and specific reconstruction plans are proposed for the pavement,non-motor vehicle road and green belt of the road.Pavement and non-motor vehicle road surfaces use permeable concrete pavement structure,but the composition of the pavement structure is different,and the green belt adopts sunken green belt.Based on the renovation plan,a low-impact development rainwater system for roads was constructed from the rainwater collection system,ecological treatment facilities and rainwater outlets in the overflow section.(3)Simulated the rainfall runoff process of urban road LID under multiple scenarios.A SWMM model was constructed for the study area,and 12 different scenarios were set based on the SWMM model.Under different scenarios,the runoff process of urban roads before and after LID reconstruction was simulated.From the analysis of the surface runoff process,it can be obtained that when LID is not used on urban roads,surface runoff,infiltration and surface water storage all increase with the increase of the recurrence period,and different rain types have little effect on each runoff result;for pipelines In the process of overflow,the 120-minute rainfall rainwater drainage requirements of the 3-year and 5-year recurrence periods can be met,and under the 10-year recurrence period,there are overflow conditions and pipeline overload conditions;for urban roads After the LID reconstruction,under the same recurrence period of different rain types,it has little effect on the maximum surface runoff and the maximum flow of the pipe and channel;under the different recurrence period of the same rain type,under the three-year recurrence period,it can be alleviated Surface water accumulation,but under the recurrence period of 5 years and 10 years,the sidewalks have accumulated water;under the same rain type and the same recurrence period,after adding LID measures,the road surface runoff flow is significantly reduced,and the road water accumulation is significantly relieved At the same time,the peak flow can be reduced after LID measures are installed on the road.