Study On Vegetative Filter Strip Influencing Runoff And Sediment Yield And Nutrient Loss On Slope

Using vegetative filter strips to prevent and control soil erosion on slopes is an important branch and hot topic of erosion research.In this thesis,artificial rainfall experiment on field soil boxes was designed to study the comprehensive effects of rainfall intensity,slope gradient and vegetative strips setting mode on slope erosion control.The effects of different setting combinations of vegetative filter strips were analyzed by clustering analysis,and based on the experimental results,the soil erosion control by vegetative filter strips were simulated with the application of VFSMOD model on enlarging scales.The optimization design on the parameters of vegetative filter strips on slopes of gully erosion area was discussed.The main results of this research are as the following:(1)According to the field investigation,the artificial rainfall experiment was designed.Three factors,i.e.,rainfall intensity,slope gradient and vegetative strips setting were selected to change.The experiment was set up with different combinations of the three factors,so as to fit and target the actual situation of gully erosion area.(2)Based on the results of experiments,the effects of the combination of three factors on vegetative filter strip intercepting runoff,sediments and nutrients were quantitatively studied.It was found that the effects of different factors could be superimposed or offset,and the rain intensity and the slope gradient showed synergistic effect,while the effects of vegetation and the other two factors were opposite.In most cases,the influence of rain intensity was dominant.(3)By the dissimilarity analysis method in clustering analysis,the similarity of the effects of vegetative filter strips on preventing soil erosion under different settings and combinations was compared and analyzed.When a certain combination of settings cannot be implemented,it can be replaced by other schemes in the same group,providing diversified choices for the practical application of vegetative filter strips on eroded slopes.(4)Based on the parameters provided by the experimental results,VFSMOD model was used to study the effects of vegetative filter strip on enlarging scales of slopes.It was found that the simulation results on 20m × 5m slope and 200m × 50m slope were in good agreement with the experimental results.On this basis,how the parameter change of vegetative filter strip influences the effects of runoff and sediments reduction was explored,and an optimized scheme was provided for the design of vegetative filter strip on different types of eroded slopes.Based on the experiments and model simulations,this study quantitatively studied the effect of vegetative filter strip on preventing soil erosion on slopes under different combinations of factors,and discussed the parameter optimization design of vegetative filter strip on erosional slopes,providing theoretical reference and data support for soil and water conservation and ecological restoration on gully erosional slopes.