The Research On The Hydrological Effect Of Stormwater Control Of Construction Project Based On The SWMM

Permeable pavement and sunken green space are typical rainwater flood utilization measures in Beijing development and construction projects.After we have obtained the data of a certain area in Haidian District,we take this area as the research object.The SWMM model is established by using CAD floor plan,Chicago rain generator and related pipe network data,under the control of different single measure and different underlying surface structure,the condition of surface rainfall,runoff and seepage,junction node hydraulic power and drain port load are studied.With a view to providing the basis and reference for the preparation of water effect report and the planning and design of rainwater utilization measures of Beijing development and construction projects and the proportion of project plot measures,the corresponding conclusions are obtained as follows:(1)Single measure scale:With the recurrence interval from 1 year to 50 year,compairing with the original development,permeable pavement and sunken green space in the aspect of the surface rainfall-runoff-infiltration:the average of the infiltration capacity increases by a large margin;the junction node waterpower:the number of overflow junction node,the total flood capacity of junction node decreases by the large margin;the load of outfall:sunken green space can’t change the discharge rate of outfall,and the permeable pavement decreases respectively 10.48%、7.54%、6.55%、4.68%、4.63%、3.70%;the average of discharge capacity,the maximum of discharge capacity,total discharge capacity decrease by a large margin.With the recurrence interval from 1 year to 50 years,when the permeable pavements is small at the recurrence interval,the hydrological effect is higher than the sunken green space;but when the permeable pavements is big at the recurrence interval,the hydrological effect of sunken green space is higher than the permeable pavements.The permeable pavements can play a role in quick leakage,regulation and storage as the engineering measures when the rainfall recurrence interval is small,but with the increase of the recurrence intervals,it is easy to have saturation and overflow because of the design limitation and the physical property of the material,and the effect of the regulation and storage of the rainfall and flood decrease gradually;however the sunken green space in the aspect of rainfall flood regulation and storage incarnate that with the increase of recurrence interval,the interception and soil infiltration of biological measures and the advantage of difficult to have saturation and product the runoff are prominent gradually,which make the advantage of rainfall flood regulation and storage of the sunken green space more obvious at the bigger recurrence interval.Therefore,the exploitation and construction project needs the combination with two measures,than it can give play to comprehensive hydrological effect better to reply the change of rainfall at the recurrence interval.(2)Different underlying surface structure scales:In the comparison among the three types of non-permeable hard lands,the land with more green area than permeable pavement(about 20%)will have better hydrological performance.Furthermore,along with the hydrological performance functions more frequently,there will be a decreasing trend present for runoff,peak volume of runoff and the increase rate of average runoff coefficient.In the scenarios of the three pavement structures:Scenario 1:the best performance is gained in the structure of 30%non-permeable hard land,45%green land and 25%pavement.Along with the green land increases from 30%to 45%,the hydrological performance gradually increases.Scenario 2:the best performance is gained in the structure of 40%non-permeable hard land,40%green land and 20%pavement.Along with the green land increases from 40%to 45%,the hydrological performance decreases.Scenario 3:the best performance is gained in the structure of 50%non-permeable hard land,30%green land and 20%pavement.Along with the green land increases from 30%to 45%,the hydrological performance gradually and slowly decreases.To conclude,with the study of the sensitivity of the critical parameters,the accuracy of this model is validated.