Published online by Cambridge University Press: 26 April 2006
The different rise or sinking velocity for different sizes or types of particles gives different vertical sampling of a wind-affected shallow-water flow. This paper derives a mathematical model for the consequent horizontal fractionation of a dilute suspension of particles when the flow is a wind-influenced perturbation from the classical logarithmic open-channel flow. Simple approximations are given for the effective horizontal velocity and for the shear dispersion tensor which preserve the perfect duality between the sensitivity of sinking particles to bed stress and the sensitivity of rising particles to surface stress.