WIND-AUGMENTED TRANSPORT AND DILUTION IN SHALLOW-WATER FLOWS

Wind blowing across shallow water contributes to secondary flow across a vertical section. For particles which are not neutrally buoyant the vertical sampling of the secondary flow is non-uniform: buoyant material drifts with the wind and slightly dense material is carried against the wind. This paper focuses attention on the joint dependence of the horizontal dilution rates upon the strength of the wind-augmented current and upon the vertical rise (or sinking) velocity of the particles. In strong wind the greatly enhanced mixing counterbalances the onshore drift and explains why shoreline pollution is not significantly correlated to the onshore wind.