Developing macroscale indicators for estuarine morphology: The case of the Scheldt estuary

A set of quantitative parameters is derived for the morphological characterization of estuaries. This is the first part of a long-term project aiming at the ecological characterization of tidal environments, which should provide practical tools for the management of such systems. The parameters apply to the macroscale, that is, the scale of the estuarine cross-section, including channels and adjacent intertidal areas. They are derived from recent theoretical models for estuarine morphology, as well as data from the tide-dominated Scheldt estuary. The set of parameters is believed to be universally representative, although this needs to be supported by further research, including data from other estuaries. The analysis suggests that morphodynamic equilibria do not form a continuum but manifest themselves as discrete steps. For each step, there is a straightforward relation between the extension of the intertidal areas and the other parameters. For the Scheldt estuary, large width-to-depth changes are necessary to jump from one equilibrium state to the other.