Flow and Transport in Regions with Aquatic Vegetation

TLDR

Aquatic vegetation canopies shape turbulence by stem diameter and spacing, with mean flow governed by canopy frontal area; dense canopies create shear layers and canopy‑scale vortices that mediate mass and momentum exchange, while sparse canopies increase bed roughness yet preserve a logarithmic velocity profile. This review aims to describe mean and turbulent flow and mass transport in the presence of aquatic vegetation. The authors examine how mean and turbulent flow and mass transport are affected by aquatic vegetation.

Abstract

This review describes mean and turbulent flow and mass transport in the presence of aquatic vegetation. Within emergent canopies, the turbulent length scales are set by the stem diameter and spacing, and the mean flow is determined by the distribution of the canopy frontal area. Near sparse submerged canopies, the bed roughness and near-bed turbulence are enhanced, but the velocity profile remains logarithmic. For dense submerged canopies, the drag discontinuity at the top of the canopy generates a shear layer, which contains canopy-scale vortices that control the exchange of mass and momentum between the canopy and the overflow. The canopy-scale vortices penetrate a finite distance into the canopy, δ e , set by the canopy drag. This length scale segregates the canopy into two regions: The upper canopy experiences energetic turbulent transport, controlled by canopy-scale vortices, whereas the lower canopy experiences diminished transport, associated with the smaller stem-scale turbulence. The canopy-scale vortices induce a waving motion in flexible blades, called a monami.