Quantifying solute mixing and flow fields in low velocity, real emergent vegetation

The heterogeneous distribution and morphology of real vegetation in shear layer environments leads to significantly different flow fields and mixing properties when compared to artificial cases. Velocity profiles and tracer concentrations were recorded in emergent, artificial vegetation and winter growth 'Typha' between the free flow and the vegetation. While the velocity shear and concentration distribution skew were less apparent in the 'Typha' than the artificial vegetation, the overall mixing, in terms of increase in variance, was greater. The increased mixing and deviation from the classical shear layer flow field is attributed to the spatial heterogeneity in vegetation distribution and a less-well defined shear layer interface due to the prevalence of sparsely vegetated zones.