Effects of soil and water conservation and water purification by vegetative filter strips

Vegetative filter strip (VFS) is one of the commonly used practices for soil and water conservation and non-point source pollution control. In August 2016, a simulated scouring experiment on soil boxes was conducted in Beijing to quantitatively evaluate the interception and removing effects of VFS (all planted with Festuca arundinacea) on runoff, total suspended solid (TSS), and pollutants (TN, TP, K). The differences between volumes of runoff and concentrations of TSS, TN, TP and K of the inflow and outflow of VFSs with different width, slope and inflow rate were examined to analyze the influence of width, slope and inflow rate on soil and water conservation and water purification effects of VFS. The results showed that the runoff reduction rate was greatly influenced by the width of VFS. The VFSs with 1, 3, and 5 m width could reduce runoff by 25.9%, 79.6% and 79.7%, respectively; the reduction rate of pollutants(TN, TP, K) increased with the increasing width, which were 51.7%-92.9%, 44.4%-98.8%, and 31.7%-97.9% correspondingly; and the reduction rate of TSS was 97.6%, 99.4% and 77.4%, respectively. Besides, the reduction rates of runoff and TSS decreased with increasing slope of VFS (3°, 7°, 10°). For the same VFS, decreasing inflow rate corresponded to increasing reduction rate of runoff and TSS, while the removal efficiencies of TN, TP and K were decreasing. The results indicate that VFS is an effective practice for reducing runoff, removing TSS and pollutants.