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Developing a Visualisation System for Simulating the Growth of Coastal Spits
LIVINGSTONE, David (firstname.lastname@example.org), Portsmouth University, Department of Geography, Buckingham House, Lion Terrace, Portsmouth, PO1 3HF, U.K.; RAPER, Jonathan, City University, Department of Information Science, School of Informatics, Northampton Square, London EC1V 0HB, U.K.
Key Words: coastal simulation, process modelling, visualisation, GIS
The paper describes the development of a system to enable a coastal simulation model to be optimised for investigating the growth of structures with a morphometry similar to that of coastal spits. The system has evolved from initial investigations using Sedsim/Wave and Visual Sedsim (Martinez and Harbaugh,1993, Pflug, Klein, Ramshorn et al., 1992) and was originally employed for simulating the growth of deltas in order to investigate the formation of geological structures (Komar and Inman, 1970). The core modelling procedures have a long history and have been developed and modified in FORTRAN during the past 25 years. The visualisation procedures developed for Sedsim3.03 were written specifically for a previous generation of Silicon Graphics so, in the new system, IDL is used for this task. This approach has a number of benefits. IDL is a multiplatform system that also can be used for more detailed exploratory data analysis, is widely used for a range of scientific applications, and has a flourishing community of developers. The main drawback is that a runtime version of IDL is required in order for the developed procedures to be usable.
Martinez developed and validated the principles behind the Sedsim/Wave models, in part, by experiments using topographies based upon contemporary situations (Martinez and Harbaugh, 1993) using data collected for Silver Strand and El Moreno beaches (Komar and Inman, 1970). The system described here is required to combine envionmental models, and digital elevation data measured for a spit on the North Norfolk coast of U.K., in order to investigate the processes that control spit development. The major issues that the system addresses are:
* Managing and analysing model variables such as wave angles, topography, and time steps
* Visualising and measuring model-generated processes such as transport rates and deposition
* Combining and comparing model results with measured field data
* Defining, tracking and comparing sub-features in both the simulated and measured data
The system has four major components:
* The process simulation models: SEDSIM/WAVE
* A model management database: SEDLINKS
* A geographical information system to create model landform situations: ARCVIEW
* A data visualisation and analysis system: IDL
A major consideration was to produce a system that was flexible enough to expand beyond its initial requirements for a generic range of applications. While the components of the system need to work together specifically to perform the task, independently they need to be able to perform functions with potential for a wider range of modelling scenarios. This objective is much more easily stated than achieved and compromises have had to be adopted for pragmatic considerations; however, the philosophy behind this approach is important, as it tries to address some of the issues that have restricted the widespread use of GIS with respect to particular kinds of statistical and mathematical environmental modelling techniques.
Martinez, P.A. and J.W. Harbaugh (1993), Simulating Nearshore Environments, In: Computer Methods in the Geosciences, vol.12, pp. 265, Pergamon Press, 1993.
Pflug, R., H. Klein, C.H. Ramshorn, M. Genter, and A. Stark (1992), 3-D Visualisation of Geologic Structures, In: Computer Graphics in Geology, Eds: R. Pflug and J.W. Harbaugh, Lecture Notes in Earth Sciences 41, p. 29-39, Springer Verlag 1992.
Komar, P.D. and D.L. Inman (1970), Longshore Sediment Transport on Beaches, Journal of Geophysical Research, 75, p. 5914-5927.