ABSTRACT
This chapter presents the principles of the basic transfer mechanisms active in estuaries. Estuaries have traditionally been divided into three geomorphologically different categories: the fjord type, the bar built type, and the coastal plain estuary. Precipitation and run-off from land into an estuary cause the level of the surface to rise so as to slope downward toward the sea. In most estuarine environments mixing processes also contribute to the horizontal dispersion of matter, particularly longitudinally, either by direct lateral exchange or shear effect, a combined effect of steady or oscillatory flow with vertical or transverse eddy diffusion. The salt wedge estuary has many features in common with the fjord. Both are highly stratified and the dynamics of the flow is determined by entrainment of water from the lower into the upper layer. Fjords are generally much deeper than coastal plain estuaries. This permits the existence of a relatively large body of semi-enclosed sea water below the brackish upper layer.
