Study On Ground Runoff Reduction And Pollutant Reduction In Urban Typical Pervious Pavement

The rapid development of urbanization has led to a rapid increase in urban impermeable area. Under the same rainfall conditions, the amount of rainwater infiltration decreases and the runoff coefficient increases. On the one hand, it wastes valuable rainwater resources and, on the other hand, Prone to urban waterlogging, threatening the people's lives and property. At the same time, human activities have exacerbated the deterioration of urban water environment,rainfall and runoff more and more pollutants, resulting in deterioration of groundwater quality,river water black phenomenon is serious. As a kind of low-impact development facility which can effectively reduce runoff and purify water quality, it is more and more attention and application.Based on the combination of field experiment and model simulation, a SWMM model suitable for simulating runoff process and pollution load is established. The effects of runoff reduction and pollutant reduction under different rainfall characteristic parameters are studied.Preliminary stucdy on the law of runoff reduction and pollutant reduction. The main contents of the thesis are as follows:(1) The pavement infiltration rate and rainfall intensity. Three kinds of pavement in accordance with the law, divided into three stages: the infiltration stage, the decline stage, the basal infiltration stage, infiltration capacity: grass brick pavement> in situ water permeable concrete pavement> permeable brick pavement. The runoff coefficient of the three kinds of pavement pavement increases with the increase of rainfall intensity, and the runoff coefficient is positively correlated with the rainfall intensity. When the rain intensity is small, three kinds of pavement are filled with runoff. When the rainfall intensity is the same, water-permeable pavement performance capacity control runoff Save porous pavement <cast porous concrete paving <grass brick pavement.(2) The removal rate of SS was similar to that of water permeable brick, permeable brick shop, grass brick and grass brick under different rain intensity. The removal rate of characteristic pollutants increases with the increase of rainfall, and the removal rate increases with the rainfall to a certain extent, and the removal effect of the permeated brick pavement is better than that of the permeable brick. The removal efficiency of COD, BOD5, TN and TP was decreased with the increase of rainfall, and the removal effect of grass brick pavement was better than that of grass. The effect of load reduction on SS, TP, BOD5, COD and TN was better for the paving and paving, and the effect of NH3'-N was the worst.(3) With the increase of the year of use, the infiltration capacity of permeated brick pavement and grass brick pavement showed a significant decrease. With the increase of the year of use, the permeability of the permeable brick pavement decreased exponentially, and the rainfall reduction capacity was weakened and the runoff was increased. The removal rate of SS was decreased and the removal rate of TP was relatively stable, and the attenuation law of SS was similar to that of infiltration and attenuation, which was exponentially decayed. For many years the use of permeable brick pavement on the COD, TN removal effect enhancement, are exponentially enhanced, after years of use can not be stable to remove NH3-N.(4) The SWMM model of pervious pavement suitable for simulated runoff process and pollution load reduction is constructed. The simulation results show that the reduction rate of the flooding pavement decreases with the increase of the rainfall recurrence period, and the runoff coefficient increases with the increase of the rainfall recurrence period. The pollutant load removal rate increases with the rainfall weight The current increase in the decline. The flooding pavement has a more significant effect on the rainfall runoff process with larger rainfall and less rainfall intensity (less reproducible). The effect of flooding pavement on the discharge of different pollutants is better than that of the pollutant under the period of 20a, and the removal effect of pollutant load is obvious when the rainfall intensity is small.