Stochastic Model for Embayed Beaches
Publication: Journal of Waterway, Port, Coastal, and Ocean Engineering
Volume 135, Issue 4
Abstract
Equilibrium models for beach morphology can be a useful engineering tool. In practice, conditions are rarely such that true equilibrium is reached or maintained. Nevertheless, equilibrium models have been used successfully in coastal studies, and extended in their application to describe quasi-equilibrium situations where, for example, wave conditions are relatively persistent over considerable periods of time. This paper describes a simple but efficient statistical method to estimate the mean and variance of crenuate shaped bays from the (long term or static) equilibrium according to the measured wave directions. The technique relies on the concept of ensemble averaging. The theoretical development is carried out by considering a sequence of problems of successive generality. Analytical solutions are first tested against results from a numerical Monte Carlo simulation which demonstrates the importance of the shape of the wave direction distribution in defining the variability of the beach position. The analytical solutions are then applied to the embayed beach at Christchurch Bay on the south coast of the United Kingdom. Hindcast wave conditions and a set of beach profile measurements covering a period of approximately are used. Comparisons are limited to three points along the embayment, at which there are sufficient measurements to calculate a variance. Nevertheless, extremely good agreement is found (to within ) between predicted and measured sample variances of shoreline position.
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Acknowledgments
The writers would like to thank Dr José Horrillo-Caraballo of the Coastal Engineering Research Group at the University of Plymouth for his assistance in preparing Figs. 5 and 6. The work described in this paper was supported by the European Community’s Sixth Framework Programme through the grant to the budget of the Integrated Project FLOODsite, Contract No. GOCE-CT-2004-505420; the writers also acknowledge the support from the project “A Risk-based Framework for Predicting Long-term Beach Erosion,” EPSRC Grant No EP/C005392/1.Disclaimer: The paper reflects the authors’ view and not those of the European Community. Neither the European Community nor any member of the FLOODsite Consortium is liable for any use of the information in this work.
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Information & Authors
Information
Published In
Journal of Waterway, Port, Coastal, and Ocean Engineering
Volume 135 • Issue 4 • July 2009
Pages: 144 - 153
Copyright
© 2009 ASCE.
History
Received: Jun 6, 2007
Accepted: Dec 10, 2008
Published online: Jun 15, 2009
Published in print: Jul 2009
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