Impacts of vegetation on flow dynamics in a reduced scale model and implications for riparian rehabilitation

Revegetation is the preferred method for rehabilitating degraded riparian lands by government agencies, landcare groups and landowners across Australia. Increased scientific involvement is necessary because most revegetation works rely on ad-hoc recipes, while the interaction of riparian vegetation with flow and sediment in rivers is an area of growing interest in fluvial geomorphology. This paper compares bare, partial and fully vegetated streambanks in order to make recommendations for bank protection works using vegetation, as well as examining the effect of reach scale variations in vegetation coverage on flow dynamics. Experiments are conducted using a reduced scale model of a natural river undergoing vegetative rehabilitation. Our hypothesis is that partial coverage can offer a similar level of protection to a fully vegetated bank face. A comparative analysis of each experiment is presented which includes depth average velocities and bed shear stresses as indicators of erosion potential. With the current emphasis on vegetative rehabilitation techniques the experiments offer potentially useful insights into more effective planting