Using a three-dimensional finite volume code with standard k-epsilon turbulence model the hydraulic resistance of willows (Salix Alba and Salix Fragilis) are modelled. The drag force approach was used by incorporating an additional term into the Navier-Stokes equations. This method is applied to model a flood event on the Wienfluss test reach in Vienna. The test reach comprised an asymmetric compound channel with vegetated floodplain of 114 metre length. The willow development has been monitored annually and this information was used in order to define the density of the willow canopy. Two vegetation geometry models are tested, a uniform density model where the density is constant with plant height and a non-uniform model where density is a function of height. The prediction in cross-sectional distribution of longitudinal velocities shows reasonable agreement for both models.
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