Using simulated emergent vegetation to alter stream flow direction within a straight experimental channel

River restoration programs often use vegetation to enhance the biological functionality, recreational opportunities. and aesthetic beauty of degraded stream corridors. Yet, none has used vegetation for the purpose of inducing a straight channel to meander. A flume-based study was designed to alter the flow pattern within a straight, degraded stream corridor by using simulated emergent vegetation of varying density placed at key locations within the channel. Placement of vegetation zones was determined using an empirical relation for equilibrium meander wavelength based on the imposed flow rate. Surface flow velocities were quantified using particle image velocimetry. The study showed that (i) flow velocity can be markedly reduced within and near the vegetation zones, (ii) flow can be diverted toward the opposite bank, and (iii) vegetation density controlled the magnitude of these effects. (C) 2002 Elsevier Science B.V. All rights reserved.