Study On The Effect Of Rainwater Runoff Control On Low Impact Development Urban Roads In Qingshan,Wuhan Based On SWMM

With the further advancement of the urbanization process and the increasing area of the underwater surface,many problems are accompanied,such as the frequent floods,water pollution,and the intensification of the supply and demand of water resources.As an important part of the urban water permeable area,the road has large runoff,and the surface easily accumulates pollutants.It poses a great threat to the urban water environment.Therefore,the change of the traditional Road tube and canal fast scheduling model,and the rational design and layout of the road LID facilities,is conducive to the realization of total annual runoff control and pollution load reduction and urban water environment improvement.Based on the guidance of low impact development concept,this paper selects the Industrial Road(between Friendship Avenue and Peace Avenue),which is a well-established and functional LID demonstration road in Qingshan District of Wuhan as the research object.the Main research contents of this article are as follows.Firstly we review the research process of storm flood models,and compare the functions,modules,operational mechanisms and application scopes of different rainwater management models.The results show that the SWMM model has the advantages of less parameter requirements,simple operation,practical and easy to handle,and its low impact development module can simulate the hydrological effect of the LID facilities of the rainfall and continuous rainfall,and evaluate the effect of the LID facilities on the control and utilization of rainwater runoff.According to the basic data requirement of SWMM model modeling and relevant literature at home and abroad,there are many factors affecting the effect of low impact development of urban road runoff and flood control,such as road area,average slope,water surface area ratio,LID facilities size and layout and proportion,soil type,underlying surface nature,groundwater level,surrounding land type,rainfall rain Strong and plant variety selection,etc.These provide the goal and direction for the later research work.Secondly,Wuhan Qingshan demonstration area is selected as the research scope.From the above aspects,the 30 roads in the research area are investigated and investigated in the field,and the typical 9 road survey results are charted and summarized.The LIDfacilities in Qingshan demonstration area mainly include grass planting ditch,rain garden,sunken green space,ecological tree pond,permeable pavement,permeable asphalt and so on.The average gradient of road surface is 0.05%-0.23%,and the proportion of impervious surface area is 10%-75%.The main underlying surface types are green space and pavement.The main plants are camphor tree,Ginkgo biloba,camphor,osmanthus,Bauhinia,red leaf Shi Nan,Ligustrum lucidum,French holly,Pyracantha,oleander,red flower wood,tooth Ye Dongqing,Lilia,Ophiopogon.and so on.Finally,Takeing the Industrial Road(between Friendship Avenue and Peace Avenue)as an example to carry out the empirical study.By building the SWMM model of traditional development model and low impact development model under different rediscovery periods,the runoff reduction effects of Bio-retention cell,Vagetable swale,Permeable brick and three combination models on urban roads was simulated.The results show that the rain and flood regulation of LID facilities is significant,which can effectively reduce the total runoff,decrease the peak flow rate and delay the peak time.The road with LID combination mode will reduce the total runoff volume by 44.2% to34.8%,the reduction rate to the peak flow rate is 83.6% to 66%,and the peak time is about 15 min.Through the study of the flood control effect of single LID measures,in the aspect of the reduction in surface runoff.we know Permeable brick and Bio-retention cell make more contribution.the runoff cut contribution rate of Permeable brick is from34.9% to 30.5%,and Bio-retention cell is from 10.8% to 3.6%.In terms of reducing the peak flow rate,the most significant contribution was made by Permeable brick,which contributed from 76.5 % to 60 %.In per unit area,the total runoff reduction efficiency of each LID facility was ordered as follows: Bio-retention cell > Permeable brick >three combination models>Vagetable swale,and the peak runoff reduction efficiency of each LID facility was ordered as follows: Bio-retention cell > Permeable brick > three combination models > Vagetable swale.The runoff reduction and peak reduction of various measures increased with the raise of rainfall intensity,but the reduction rate showed a general decline trend.The control effect of LID installation on light rain(once in2 years and below)is more obvious and better under combination mode.The purpose of this study is to quantitatively evaluate the contral effects of low impact development facilities on Rainwater runoff from Urban Roads,and to compareand analyze the contribution and reduction efficiency of individual LID facility,in order to provide some reference value for other similar urban road construction under Low impact development concepts.