Wind-induced mixing of buoyant plumes

In the absence of wind a buoyant plume of effluent discharged to the sea some distance from the shoreline is most frequently swept nearly parallel to the coast by the tidal currents. The main reason for a surface plume to approach the beach is if there is a wind blowing onshore. Although the wind has this adverse effect of allowing the effluent to reach the shore it tends at the same time to cause additional mixing so reducing the pollution risk. It is important in planning outfalls to know the extent of this extra mixing.