Evaluation of runup characteristics on the NSW coast

Abstract

Communities and infrastructure along the coast of New South Wales, Australia, are vulnerable to coastal inundation from the combined impacts of ocean tides, storm surge, wave setup, wave run-up and wave overtopping. The focus of the current work is to examine the potential for coastal inundation on beaches and dunes on the open coast of NSW through the evaluation of wave run-up. To achieve this we combine information on tides, surge and wave runup to examine dune overtopping potential. The study utilises data from the NSW wave and ocean tide gauge network and an extensive set of beach profile and grainsize data covering over 200 beaches as well as available photogrammetry and LiDAR data. Ocean still water level and design nearshore wave conditions are used together with beach slope data to calculate wave run-up height. Choice of appropriate wave run-up formulation is evaluated through the use of available long term datasets from Narrabeen and Moruya. Geographical variability in relevant beach/dune characteristics including beach slope and dune height are examined using survey (RTK-GPS), photogrammetry and LiDAR data. Overtopping potential for various design events (e.g. 5y, 20y, 100y storms) is examined through the overlay of predicted run-up heights on high resolution digital elevation models at each pilot study site.