Estuary schematisation in behaviour-oriented modelling

Abstract

ASMITA (Aggregated Scale Morphological Interaction between Tidal basin and the Adjacent coast) is a behaviour-oriented modelling approach which represents estuarine systems schematically. It was originally developed for ‘classic’ tidal inlets such as those found in the Dutch Wadden Sea and Venice lagoons, where schematisations of two or three interacting elements (e.g. flat, channel and possibly an ebb-tidal delta) are appropriate. However, estuaries show a much wider range of form and human interference than these cases. This paper presents results for two UK estuaries with differing morphologies and management histories. The Ribble Estuary and Southampton Water are poorly represented by standard two and three element schematisations, and required novel schematisations which considered the dominant processes shaping the two estuaries. The new schematisations gave model predictions that (1) are better than the baseline assumption of no change through time, (2) are better than standard schematisations and (3) are physically reasonably whilst retaining simplicity. These results demonstrate a possible generic methodology to test different schematisations using simple models to characterise estuarine morphodynamics as a preliminary stage of estuary assessment.