Study On The Influence Of Rainfall Intensity On Runoff Process Of Rainwater Garden

In the process of urban road construction,the watertight pavement replaces the original surface and changes the hydrological characteristics of the development area,resulting in shortening the time of surface runoff,increasing the runoff,decreasing the flow peak,reducing the water accumulation and decreasing the runoff infiltration process,even disappear.Easily lead to the rapid collection and spread of regional rainwater runoff on roads,and form the road water,even can cause a wide range of floods in the town when it get serious.This paper studies on the rainwater garden and seepage pavement system,and use the biological retention and permeable pavement of road on both sides,diverse?regulates and infiltrates road pavement runoff and rainwater garden under the surface of the rain,finally achieves the path of the peak flow reduction and retention of emissions and infiltration of underground runoff.In order to evaluate the operational efficiency and reliability of the system,a constant current-unsteady flow calculation model is designed for the surface and pipe network convergence characteristics of the study area.This paper analyzes the surface and pipeline runoff of the common road and the road with the rainwater garden and the seepage pavement system,and analyzes the relevant parameters,compares the variation of the runoff and outflow flow,the peak flow and the peak time,finally evaluate the effect of rainwater garden and seepage pavement system.This paper's research object is the rainwater garden and seepage pavement system of XinJin County in Chengdu,and the calculation model of surface and pipe network convergence are constructed.The following results are obtained by simulation analysis.(1)By monitoring the rainfall in the study area,the rainfall process data were collected and the rainfall characteristics of the study area during the experiment were analyzed.(2)The motion wave method is used to solve the Saint-Venant equations to calculate the unsteady flow of the pipe network,and simulate and calculate the regional rainfall runoff process.The results show that the simulation is suitable for the rainfall of more than 15mm during the design of pipe network.And the simulation results are poor with rainfall less than 15 mm,short duration of rainfall,and large reproducibility.(3)By analyzing the hydraulic parameters of the model simulation process,The model with better simulation results of rainfall,the parameter value is set in the normal experience range,the simulation results are poor with less rain,the short duration rainfall and the rainstorm,the parameter setting are very different from the experience value.(4)By analyzing the differences of rainwater trunk node peak,peak time and total runoff input during a rainfall period,gaining that build the road of a rainwater garden system can reduce the runoff peak and cut the efficiency of about 30%.And there is a better retention effect on the surface runoff,and the more obvious the effect of the downstream stay is,the overall residence time is about 30min.It can also be better to regulate the surface runoff,the storage effect of about 35%.