Modelling sediment trapping in vegetative filter strips on steep slopes

• Published in: Hydrological processes 2023-01, Vol.37 (1), p.n/a
• Main Authors: Wu, Songbai, Chui, Ting Fong May, Chen, Li, Chow, Chun Hon Christopher
• Format: Article
• Language: English
• Subjects: Agreements; Bed load; erosion; grass buffer strips; Inflow; Laboratory experimentation; Laboratory experiments; Modelling; Outflow; Performance evaluation; Runoff; Sediment; Sediment load; sediment reduction; Sediment transport; Slope; slope effect; Slopes; Soil properties; Transport equations; Transport processes; Trapping
• ISSN: 0885-6087; 1099-1085
• DOI: 10.1002/hyp.14793

The slope effects on sediment trapping process in vegetative filter strips (VFS) are usually neglected in current modelling practices for VFS operation, which hamper the VFS design and performance evaluation, especially on steep slopes. To fill the knowledge gap, 12 laboratory experiments of sediment trapping in VFS were conducted with three different inflow discharge (80, 100, and 120 ml s−1) and four slope angles (5,10, 15, and 20°). The experimental results show that, on steep slopes (10, 15, and 20°), a part of trapped sediment particles in VFS can be eroded again and then dragged to the downstream as bed load, whilst they do not move on gentle slope (5°). To describe the complex processes, a simple and effective modelling framework was developed for sloped VFS by coupling the slope infiltration, runoff, and modified sediment transport model. The model was tested against the experimental results and good agreements between the modelled and observed results were found in both runoff and sediment transport processes for all cases. On steep slopes, the sediment trapping performance of VFS decreases significantly because the erosion of deposited sediment particles can account for more than 60% of the sediment load in the outflow. The slope effect on sediment trapping efficiency of VFS varies greatly with soil, VFS, and slope properties. The model was compared with previous sediment transport equation and found that both methods can satisfactorily predict the sediment trapping of VFS on gentle slopes, but previous sediment transport equation is likely to overestimate the sediment trapping efficiency in VFS on steep slopes. This model is expected to provide a more realistic and accurate method for predicting runoff and sediment reduction in VFS on sloping surfaces. Erosion of deposited particles as bed load substantially decrease the sediment trapping efficiency of vegetative filter strips (VFS) on steep slopes An efficient framework is presented to simulate sediment trapping in VFS on steep slopes Slope effect on sediment trapping performance of VFS varies greatly with inflow, soil, or VFS properties