Stability Effects on Turbulent Mixing in Tidal Currents

Abstract

Vertical mixing in many estuaries and coastal waters depends mainly on the turbulence due to tidal currents. At the same time, the influx of relatively low salinity water gives rise to vertical gradients of density which inhibit the mixing. Values of the vertical eddy diffusivity Kz , effective over a complete tidal period, have been derived from observations in certain areas and are related to the stability conditions. The values of Kz decrease rather more rapidly with increasing Richardson number than would be expected from the results reported for analogous types of flow.