Sea Level Rise, BMT WBM Model Shoreline Recession
Shoreline Recession Modelling of the Coffs Coastline
Projected sea level rise will increase the risk from shoreline recession to coastal communities into the future. To assist Coffs Harbour City Council in minimising exposure to coastal risks for existing and future development, BMT WBM prepared a Coastal Hazards Definition Study, outlining the likely extent of coastal hazards at present, 2050 and 2100.
The world’s best practice Shoreline Evolution Model (SEM) developed by BMT WBM’s Dean Patterson was used to assess shoreline recession due to sea level rise along the 80 km Coffs coastline. The SEM is a considerable advance on the nearly 50 year old Bruun Rule (1962), the former standard for estimating recession due to sea level rise.
The SEM accounts for both cross-shore and longshore sediment transport, and can model headlands, reefs, harbour breakwaters and other coastline features, in estimating the shoreline response to sea level rise. In the Coffs Harbour LGA, the SEM predicted enhanced recession at the southern ends of beaches due to northerly longshore sediment transport, as well as in the lee of nearshore reefs. The model also showed that impacts of the construction of the harbour breakwaters, some 100 years ago, were still being felt on some northern beaches.
The SEM can be applied to any open coast shoreline in the world that has natural or man-made structural features and wave-driven transport to predict shoreline recession due to sea level rise. The SEM can also be used to predict the impact of structures such as groynes and breakwaters on open coast shorelines.
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