Impacts of vegetation and pavement runoff concentration on rural roadside slope erosions in Three Gorge Reservoir area

The development of road networks is beneficial to promoting mountainous region’s economy; however, it can cause a series of environmental issues, such as the serious soil erosion on roadside slopes. This study aims to evaluate the effectiveness of four vegetation restoration schemes in controlling the roadside slope erosion under simulated rainfall events. The schemes are natural restoration (NR), grass (GR), grass and shrub (GS) and sodded strip (SS). At the same time, rainfall simulation and scour test are conducted to quantify the contribution of pavement flow to fill slope runoff along roads and sediment production. Results show that the GS scheme has a higher capability to reducing rainfall runoff and sediment trapping compared to other three means. On the fill slope, both GS and GR schemes significantly outperform other twos in reducing rainfall erosion and pavement flow scouring. The pavement flow concentration has a remarkable effect on the acceleration of fill slope erosion, just as accelerated the runoff generation, the corresponding rainfall runoff and sediment yield are increased. For a best management of mountainous road erosions, apart from choosing a suitable preventive measure, more efforts should be focused on the road rational planning and design to better control runoff generation and concentration.