A theoretical framework for the description of estuaries

A theoretical framework for the description of an estuarine system is outlined, with particular reference to the Baltic. This description, in terms of continuous functions of salinity and time, may be considered as an improvement of existing “box models” which are inherently incapable of making efficient use of hydrographic data. Relations between deep water supply and internal mixing properties, as well as the equations controlling diffusion of substances in general, are derived and their applicability discussed.