Abstract:
Abstract
Methods are proposed to take account of the effect of emergent vegetation (which covers
only part of the channel bed) on conveyance and depth-averaged velocity in open
channels. For emergent vegetation strips parallel to the flow direction, discharge can be
predicted separately for each vegetated or non-vegetated zone. The equations of Kaiser
(1985) and Nuding (1991, 1994) can predict the influence of the vegetation on
conveyance within the non-vegetated zone via the composite roughness formula of
Pavlovski (1931). In order to predict the lateral distribution of depth-averaged velocity
within the non-vegetated zone, the equations of Nuding (1991, 1994) have been modified
to take account of the relation between non-vegetated zone width, apparent shear stress
on the vegetation interface and the maximum velocity which will occur. For more
complex geometries, two-dimensional numerical hydraulic models using existing
software and existing relations for the prediction of eddy viscosity are recommended.
