Sediment deposition within and around a finite patch of model vegetation over a range of channel velocity
The interaction between flow and vegetation creates feedbacks to deposition that vary with channel velocity. This experimental study describes how channel velocity and stem generated turbulence influence the deposition within and around an emergent patch of model vegetation, with a particular focus on deposition within the patch. The Reynolds number threshold for stem scale turbulence generation was determined using velocity spectra and flow visualization. At high channel velocity resuspension occurred in the bare regions of the channel and a nonuniform spatial distribution of net deposition was observed around and within the patch. In contrast, at low channel velocity there was no (or limited) resuspension and a uniform distribution of net deposition was observed around and within the patch. The deposition inside the patch was enhanced, relative to a bare channel control, only when the following two criteria were met: (1) the absence of stem turbulence, and (2) the presence of sediment resuspension in the bare channel. Comparison to previous lab and field studies further support these criteria.