Transverse mixing in sinuous natural open channel flows

Accurate modelling of transport and mixing of solutes within natural watercourses is vital for environmental management. A lack of understanding of the dominant processes, particularly quantification of transverse mixing processes in natural channels, severely limits the accuracy and usefulness of such modelling. This paper presents results from tracer and hydrodynamic studies conducted on a 'natural' channel form under laboratory conditions. The measurements are analysed using the standard method of moments and the variation of the resulting mixing coefficients examined with respect to the variations in the natural channel geometry and hydrodynamic measurements. Normalisation of the resulting transverse mixing coefficients is investigated. The work conclusively shows that the transverse mixing coefficient varies in direct relation to channel curvature, the variation is cyclic with meander geometry.