Proceedings of the 6 th International Conference on the Application of Physical Modelling in Coastal and Port Engineering and Science (Coastlab16)

During the design process for a seawall, preliminary structural geometry is rapidly estimated using a range of empirical techniques. These accepted techniques are generally intended to be conservative, resulting in an initially over-designed structure. This geometry is subsequently refined using physical modelling to ensure hydraulic stability (without over conservatism) and reduce the risk of the design criteria being exceeded during its working life. This paper presents the designs developed both empirically and through physical modelling for a seawall located at the back of a sandy beach on the Australian East Coast. The authors collectively acted as both designer and physical modeller for the client, providing the unique opportunity to review the assumptions inherent in their own preliminary empirical design following the conclusion of a physical modelling program. While the use of physical modelling for coastal engineering projects is almost always recommended, commentary is provided as to which processes were reasonably well described empirically for this case study and which processes introduced over-conservatism throughout the ensuing preliminary design. Given the same offshore wave and still water level boundary conditions as the physical model, inaccuracies in the preliminary design water depth at the structure were found to have significant impacts on subsequent design parameters