Hydrodynamic modelling as a basis for explaining estuarine environmental dynamics: some computational and methodological issues

Abstract

This paper outlines some computational and methodological issues arising from the application of a two-dimensional hydrodynamic model to the Blyth Estuary, Suffolk. The Blyth serves as a case study for a programme of research into the environmental dynamics of anthropogenically modified estuaries in south-east England. Central to this work is the implementation of hydrodynamic and sediment transport models to characterize the present process regime; support further studies of intertidal processes; and, ultimately, provide a basis for the investigation of joint management and environmental change scenarios. Two aspects of the hydrodynamic modelling are considered. First, the practicalities of modelling are explored, in terms of our ability to represent flow within a morphologically complex environment. Crucial issues include the quantity and quality of terrain data; the availability of software tools to permit their manipulation and interpolation on to computational meshes; and the ability of the model geometry to represent real world complexity. A feature of this study is the inclusion of a ‘pre-modelling’ simulation intended to approximate the behaviour and properties of the intertidal parts of the computational mesh. MeshTool, a MATLAB-based Graphical User Interface (GUI) tool, has been developed to provide visualization and simulation facilities that greatly reduce the need for debugging of the mesh via repeated execution of the fully hydrodynamic code. Second, the role of numerical modelling as a basis for geomorphological explanation is briefly explored. Physically based, high space–time resolution, models are of particular value where they facilitate a shift from ‘extensive’ to ‘intensive’ modes of research. Such a transition affords an increase in explanatory power: the emergent properties of physically based numerical simulations provide a more secure foundation for generalization, and the models themselves, through the ‘production of data’, provide a framework for informing further research designs. As this study demonstrates, however, higher resolution terrain data and improved model representation of important processes operating at a subelement scale are required before this potential can be fully realized. Copyright © 2000 John Wiley & Sons, Ltd.