Experimental Study On Control Effect Of Volume And Peak Flow About Runoff In Road On-site Infiltration And Retention Measures

The acceleration of the urbanization has transformed the original natural landform into impervious surfaces.Then,surface runoff increases rapidly,the infiltration and evaporation of stormwater decreases significantly,and the original hydrological cycle of the city has changed.Traditionally,the runoff is discharged into the municipal wastewater treatment plant or receiving water through the combined system and separate system,which causes CSO,the pollution of initial stormwater and increases the pressure of sewer due to the raise in the volume and peak flow of the runoff.At present,urban stromwater management advocates the control of stromwater from the source to reduce the risk of ponding.Pervious asphalt pavement and bioretention facility are typical road on-site infiltration and retention measures,which are widely used in the construction of sponge city.They have good control effects on the peak flow of runoff,the total amount of stormwater discharged and time of peak flow delayed.Currently,the research on hydrology and water quality control effect of single facility has been carried out at home and abroad.The research on hydrological control effect of road on-site infiltration and retention measures is less,and there is much less research on the process of the runoff yield and confluence and the control effect of runoff in road on-site infiltration and retention measures.In this paper,the road on-site infiltration and retention measures is taken as the research object.The effect of road on-site infiltration and retention measures on the control of runoff is analyzed under different recurrence intervals,rainfall profiles,duration of rainfall and the depth of water ponding area of bioretention facility.The main research contents and conclusions of this paper are as follows:(1)The process of infiltration and the runoff yield and confluence of road on-site infiltration and retention measures were analyzed.According to the principle of hydrology,the thickness of water film in pervious asphalt pavement was also studied and analyzed.(2)The effect of pervious asphalt pavement and road on-site infiltration and retention measures on the control of runoff volume was studied.The results show that the control effect of runoff volume in pervious asphalt pavement is 10.09%~32.26% under different rainfall scenarios,and the control effect has no obvious relationship with rainfall profiles.The control effect of runoff volume in road on-site infiltration and retention measures is 62.46%~96.74% under different rainfall scenarios,which indicates that the control effect is improved after the increase of bioretention facility.As the recurrence interval,duration of rainfall and rainfall profiles increase,the control effect of runoff volume in road on-site infiltration and retention measures has reduced.As the depth of water ponding area of bioretention facility increases,the control effect gradually increases.(3)The contribution of the pervious asphalt pavement and bioretention facility to the effect of the runoff volume in road on-site infiltration and retention measures is analyzed.It is found that the bioretention facility is the main control facility,and the contribution ratio is more than 65%.The SPSS software was used to analyze the correlation between the percent of stormwater undischarged of road on-site infiltration and retention measures and factors,and the result is: the depth of water ponding area of bioretention facility.> the quantity of rainfall > duration of rainfall > peak rainfall intensity > rainfall profile.(4)The control effect of peak flow and time of peak flow occurred in pervious asphalt pavement and road on-site infiltration and retention measures discharged was analyzed.The results show that the control effect of peak flow and time of peak flow occurred of road on-site infiltration and retention measures discharged was improved after the bioretention facility is combined with pervious asphalt pavement.The reduction rate of stormwater peak flow discharged in road on-site infiltration and retention measures is 29.18%~90.25%,and time of peak flow delayed is 65s~287s.Compared with pervious asphalt pavement,the reduction rate of stormwater peak flow discharged in road on-site infiltration and retention measures increased by 14.83%~40.86%,and time of peak flow delayed increased by 28s~131s.As the recurrence interval increases,the contribution of the reduction rate of stormwater peak flow discharged about pervious asphalt pavement decreases,and the contribution about the bioretention facility increases.Under different rainfall scenarios,the pervious asphalt pavement plays a major role in the time of peak flow delayed in road on-site infiltration and retention measures discharged,with a contribution of more than 56%.(5)The SPSS software was used to analyze the correlation between reduction rate of stormwater discharged peak flow of road on-site infiltration and retention measures and factors The result as follows: the quantity of rainfall > the depth of water ponding area of bioretention facility > peak rain intensity> rainfall profile> duration of rainfall.It is concluded that the correlation between time of peak flow delayed of road on-site infiltration and retention measures discharged and factors is the quantity of rainfall> peak rain intensity > duration of rainfall > the depth of water ponding area of bioretention facility > rainfall profile.(6)The experimental results show that variable runoff coefficient method-isochrone method is more suitable for the runoff yield and confluence of the pervious asphalt pavement under the experimental.A correction method of the rational formula method based on pervious asphalt pavement is proposed.Combined with the experimental datas,the correction parameters of the rational formula method under the experimental conditions are given to provide reference for engineering design calculation.