Author(s): Sam Gorrick; José F. Rodríguez

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Keywords: Bank vegetation; flow structure; force balance; meander bend; variable-width channel

Abstract: The typical flow dynamics of meandering streams related to curvature and associated bed topography can be altered by stream width variations and vegetation. This paper presents laboratory experiments conducted in a reduced-scale model of a low-sinuosity, variable-width bend with and without vegetation on the outer bank. Measurements of velocities and water surface elevations on a dense grid allowed, for the first time, the quantification of fluxes and forces that influence flow structure. Experiments without vegetation showed superelevation of water surface along the outer bank due to centrifugal effects, accompanied by longitudinal variations in water-surface gradients associated with width changes, as the channel was narrower near the bend inflection and wider near the apex. High outer bank velocities developed in the downstream part of the bend due to the absence of well-developed bed topography. Vegetation reduced centrifugal effects at the bend entrance but enhanced them at the bend exit, affecting flow in the downstream bend.

DOI: https://doi.org/10.1080/00221686.2014.939109

Year: 2014