The estimation of estuary dimensions using a simplified form model and the exogenous controls

The most common definition of an equilibrium condition for estuaries and inlets makes use of the well documented relationship between tidal prism and the cross-sectional area of the channel. However, the tidal prism is itself a function of the morphology of the tidal basin. It would therefore be useful to be able to define the key dimensions of estuaries and inlets based on properties that are external to the estuary itself. This would then provide a more rigorous basis for understanding how systems are being perturbed by developments, or other influences such as climate change. An idealized representation of the threedimensional (3D) form of an estuary has been proposed and is here applied to a wide range of UK estuaries to explore its ability to predict the gross properties of a range of different estuary types. When considering just tidal flow, the model was found to provide an adequate representation, however, the inclusion of wave action was found to significantly improve the predictive power of the model. The exogenous parameters therefore provide a basis for determining the estuary dimensions and how they are likely to change over time. This in turn provokes a broader definition of an estuary than those commonly cited. Copyright (C) 2012 John Wiley & Sons, Ltd.