| The concept of sponge city construction has been rapidly promoted and developed in our country since 2013.China carried out the first national pilot for the construction of sponge city in 2015,Yuelai New City in Chongqing was approved as one of those cities.The stormwater runoff pollution control is one of the important goals of sponge city construction.In order to cooperate with the pilot work of sponge city construction,and provide technical support for the design and maintenance of sponge city technical measures,the monitoring and characteristics analysis of stormwater runoff in Yuelai New City need to be carried out urgently.In this study,the stormwater runoff of regional stormwater inspection well,road intersection,lawn,roof,low-density residential area and high-density residential area was selected as the research object.The temporal variation of pollutants,the correlation between pollutants,the first flush effect,the event mean concentration(EMC),pollution loads and influencing factors of pollutants were analyzed and studied.The main conclusions of the study are shown as follows:(1)The concentration of pollutants follow rainfall time lesser,and the declining trend is steep before and gentle later.The pollutants concentration decay occurs mainly 10-20 min after the runoff generated.pH is relatively stable,which fluctuates within a certain range.The initial runoff pollutions are serious,but the degree of pollutions are different for six types of underlying surface.The main pollutants are SS,COD,TN and Fe,and TP pollution is relatively light.At the end of rainfall,the stormwater runoff tends to be stable,and the COD and TP pollution are lighter,but SS,TN and Fe pollution are still serious.It is found that the pollutants in rainwater runoff are related to SS.And the correlation between COD and SS was generally good,but the correlation between SS and TN,TP,Fe was poor.(2)The event mean concentration(EMC)of SS in the stormwater runoff from CQEXPO is higher than that from Yuanyang.In the stormwater runoff,the COD of high-density residential areas,the TN of roof and the TP of lawn are higher than those in other underlying surfaces.The event mean concentrations(EMC)of Fe of all underlying surfaces runoff are high except roof.The total pollution load of SS and TP in regional stormwater runoff is highest,which are 90.378t/km2 and 0.019t/km2.The high-density residential area contributes most to urban runoff COD pollution,whose total pollution load of COD is 9.943t/km2.The total pollution load of TN in stormwater runoff from roof is higher than other underlying surfaces,its value is 0.577t/km2.(3)The first flush effects of six types of underlying surface is obvious except lawn.The first flush effect is related to the rainfall intensity and rain pattern,and the overall performance is heavy rain> moderate rain> light rain.If the rainfall intensity is greater,the rainfall is more concentrated at the beginning of raining,the first flush effect is more obvious.After the analysis,it is suggested that 40% of the initial stormwater runoff should be taken as control(2.92mm).The main influencing factors of stormwater runoff pollution are rainfall,underlying surface type and seasonal variation.(4)The main pollutions that need to be controlled of stormwater runoff should be SS,COD,TN and Fe,and the control measures of runoff pollutions should be arranged for the underlying surface type.The recommended values of the initial retention time for the regional stormwater,road,lawn,roof,low-density residential areas and high-density residential areas are 15-25 min,10-25 min,10-15 min,15-25 min,15-20 min,10-20 min. |
PDF Full Text Request