Study On Runoff Control Effect Of Concave And Convex Greenbelt

Urban green space system as one of the ways to control the total amount of urban runoff,its infiltration and production flow have been influenced by The variation of surface undulation,slope gradient and soil permeability.So far,the determination of the total amount of regional runoff should be based on the surface type,soil properties,topography and other factors.This study is taking concave convex green space and building waste material as the research object,putting to use the theory of green land runoff infiltration and water balance to confirm the calculation method of runoff volume for concave and convex green space.Studying on the variation of surface runoff infiltration under the constant rainfall intensity,the effects of surface undulation and soil permeability improvement on surface runoff and infiltration process,setting up a correlation between topographic relief and total runoff and total runoff control rate,by means of artificial rainfall experiment,surface elevation measurement technology and DEM modeling method.Studying on the improvement of soil permeability and p H value of infiltration water with consolidated mortar and aerated concrete brick through the permeability column experiment.The main conclusions are as follows:1.The runoff process of flat slope surface with constant rainfall intensity contains three stages that is catchment runoff,stability and water back stage.There was a negatively power function correlation between runoff start time and rainfall intensity,a negatively quadratic function correlation with total amount of runoff.There was a significant positive correlation between stable runoff intensity and total runoff and rainfall intensity.The stable infiltration strength increases with the increase of rainfall intensity,and finally tends to be stable.2.The formula for calculating the total runoff volume of concave and convex green space is(7)(8)(7)(8)2 acosqtW?10 VSt???Ut0.9251---(28).There was no significant relationship between the runoff process and the surface uplift.There was a negative correlation with quadratic function between the total runoff and steady runoff intensity and surface depression.There is a positive correlation with quadratic function between the beginning time of runoff and surface depression.There is a positive correlation with linear functionbetween the critical rainfall intensity.There is a positive correlation with quadratic function between total runoff control rate and surface depression..The relationship between surface undulation and stable infiltration intensity is linear,under the condition of homogeneous soil and underground runoff.But the effect of the surface depression on the stability of the infiltration intensity is obvious.3.Adding 50% of consolidated mortar and aerated concrete brick,Soil permeability increased 5.7 times and 3.8 times.Consolidated mortar and aerated concrete brick can effectively improve soil permeability.The permeability of the consolidated mortar is 1.64 times higher than that of the aerated concrete brick.The influence of aerated concrete filler on the seepage water p H value is lower than that of consolidated mortar.The increase of soil permeability can obviously delay the beginning time of runoff.When green soil infiltration intensity increased from 0.70mm/min to 0.97mm/min,at least 26.06% of the runoff intensity was reduced,and the total amount of runoff was cut down by at least 26.30%,and the total control rate of runoff increased by at least 10%,Acceptable impervious area are raised by 46.47%.