Effects of Added Vegetation on Sand Bar Stability and Stream Hydrodynamics

Vegetation was added to a fully developed sandy point bar in the meander of a constructed stream. Significant changes in the flow structure and bed topography were observed. As expected, the addition of vegetative resistance decreased the depth-averaged streamwise velocity over the bar and increased it in the open region. In addition, the secondary circulation increased in strength but became confined to the deepest section of the channel. Over the point bar, the secondary flow was entirely outward, i.e., toward the outer bank. The changes in flow led to changes in bar shape. Although the region of the bar closest to the inner bank accumulated sediment, erosion of the bar and the removal of plants by scouring were observed at the interface between the planted bar and the open channel. DOI: 10.1061/ ASCE HY.1943-7900.0000215 CE Database subject headings: Meandering streams; Secondary flow; Rivers and streams; Restoration; Vegetation; River bank erosion; Sediment transport; Hydrodynamics. Author keywords: Meandering streams; Secondary flow; Stream restoration; Riverine bars; Riparian vegetation; Riverbank erosion; Sediment transport.