Influence of inflow rate of runoff on purification effectiveness of vegetative filter strip

Many factors affect the effectiveness of vegetative filter strip (VFS), and the purification efficiency of VFS also varies from time to time in a rainfall runoff process. Thus, the effects of inflow rate during storm-runoff on pollutants trapping by vegetative filter strips were analyzed based on the measured data from field plot experiments in this paper. Results showed that the purification effectiveness of VFS on suspended solids, total nitrogen, total phosphorus, particulate nitrogen and particulate phosphorus concentration changed greatly with different inflow rates. Furthermore, the effectiveness of VFS was more obvious along with smaller inflow rate, and grass strip had the best purification effect compared with other strips. Comparing grain diameter distribution at import and export section of each VFS, it showed more efficiency on coarse particles trapping by VFS. Therefore, the deposition of coarse particles was one of main mechanisms of pollutants removal as vegetation reduces flow velocity. The results of this study could provide a scientific support for the application of integrated constructed vegetative filter strips in northwest China.