Retention time and dispersion associated with submerged aquatic canopies Nepf, Heidi M. Ghisalberti, Marco White, Brian L. Murphy, E. 2010-05-18T18:50:23Z 2010-05-18T18:50:23Z 2007-04-18
dc.description Author Posting. © American Geophysical Union, 2007. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Water Resources Research 43 (2007): W04422, doi:10.1029/2006WR005362. en_US
dc.description.abstract The shear layer at the top of a submerged canopy generates coherent vortices that control exchange between the canopy and the overflowing water. Unlike free shear layers, the vortices in a canopy shear layer do not grow continuously downstream but reach and maintain a finite scale determined by a balance between shear production and canopy dissipation. This balance defines the length scale of vortex penetration into the canopy, δ e , and the region of rapid exchange between the canopy and overflow. Deeper within the canopy, transport is constrained by smaller turbulence scales. A two-box canopy model is proposed on the basis of the length scale δ e . Using diffusivity and exchange rates defined in previous studies, the model predicts the timescale required to flush the canopy through vertical exchange over a range of canopy density and height. The predicted canopy retention times, which range from minutes to an hour, are consistent with canopy retention inferred from tracer observations in the field and comparable to retention times for some hyporheic regions. The timescale for vertical exchange, along with the in-canopy velocity, determines the minimum canopy length for which vertical exchange dominates water renewal. Shorter canopies renew interior water through longitudinal advection. Finally, canopy water retention influences longitudinal dispersion through a transient storage process. When vertical exchange controls canopy retention, the transient storage dispersion increases with canopy height. When longitudinal advection controls water renewal, dispersion increases with canopy patch length. en_US
dc.description.sponsorship This material is based upon work supported by the National Science Foundation under grant EAR0309188. en_US
dc.format.mimetype application/pdf
dc.identifier.citation Water Resources Research 43 (2007): W04422 en_US
dc.identifier.doi 10.1029/2006WR005362
dc.language.iso en_US en_US
dc.publisher American Geophysical Union en_US
dc.subject Macrophytes en_US
dc.subject Retention en_US
dc.subject Longitudinal dispersion en_US
dc.title Retention time and dispersion associated with submerged aquatic canopies en_US
dc.type Article en_US
dspace.entity.type Publication
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