Study On Storm Flood Regulated Mechanism Of Urban Surface Drainage System

In recent years,due to the influence of extreme climate changes and urbanization process,the frequent rainstorm flood/waterlogging disasters in China have become a prominent issue that affects the normal development of society.However,the existing urban drainage engineering construction is still relatively lagging,it cannot effectively respond to rainfall events within the prevention and control standards,and it cannot ensure the safe operation of important urban infrastructure under excessive rainstorm.In order to improve the resilience of urban drainage system for extreme rainstorm and provide suggestions and references for flood/waterlogging disasters prevention,this paper analyzed the advantages of surface drainage design using urban storm flood simulation technology,and focused on the stormwater drainage and regulation rules of road drainage system and surface drainage system by using GAST,SWMM and coupling model.The main contents and conclusions are as follows:(1)This paper has established the road drainage system model of traditional fast drainage mode and sponge storage and drainage combined mode,and quantitatively analyzed the drainage and regulation effect under different small recurrence interval rainfall conditions.Research has shown that with the increase of recurrence interval and longitudinal slope,the proportion of pavement drainage increases;with the increase of cross slope,the proportion of pavement drainage decreases.Compared with the cross slope,changes in the longitudinal slope have a greater impact on stormwater discharge and regulation.Compared with traditional drainage model,concave green spaces have a significant retention effect in small recurrence interval and small longitudinal slope scenarios,which can effectively reduce the peak discharge of pipeline drainage and delay the peak time.However,the total runoff and peak of pavement drainage under the sponge storage and drainage combination mode are higher.In the planning and design of road drainage system,it is necessary to increase the length and number of curb openings to further control pavement runoff.(2)This paper has established an ideal urban drainage model,simulated the drainage process of surface road and underground pipeline,quantitatively analyzed the drainage effect of each part,and clarified respective functional position.Research has found that with the increase of rainfall recurrence interval,the proportion of pavement drainage increases,and the proportion of pipeline drainage decreases.The pipe drainage system plays a large role in all recurrence intervals,and the effect is more significant in small recurrence intervals;the pavement drainage system mainly discharges excessive runoff before and after stormwater peak in large recurrence interval to alleviate the urban waterlogging problem.The smooth pavement and pipeline drainage system cooperate each other,improving the comprehensive drainage capacity and urban resilience.(3)This paper has established a surface drainage model for the Unit A of Silk Road Technology Venture Park Area of Fengxi New City,analyzed the stormwater and flood control effects of each component in this system.Overall,the drainage system of Unit A mainly is relied on drainage and supplemented by storage.The superelevation of the canals has improved the drainage effect by about 20%.The online green space is relatively small,only controlled 2.366%of the runoff at most,indicating that the storage effect is limited.Due to the high efficiency of the surface drainage system,only about 10%of the pipes and canals are filled and overflow during the 100a recurrence interval,resulting in relatively low drainage risks.For the pipes and canals with insufficient drainage capacity,the cross-sections have been optimized to achieve the purpose of safely discharging runoff under the designed standard rainfall,which can provide suggestions for the drainage system of Unit A.At the same time,this paper analyzed the stormwater runoff status of the whole area under the excessive rainstorm,and determined the main drainage pathway,which can provide reference for the preparation of emergency plans;the assessment found that the risk level of waterlogging and drainage under the excessive rainstorm is low,the highest risk is only medium,indicating that there was basically no serious flood disaster.The overall drainage design of Unit A is advanced,the vertical planning is reasonable,and the drainage system is complete,so it can effectively deal with conventional or excessive rainstorm.The formed surface drainage mode can provide reference for other cities stormwater management and promote the development of urban drainage system.