A centennial-scale view of wave climate change impacts on shoreface and shoreline stability along drift-aligned coasts

Sea-level rise is often identified as the principal driver of shoreline recession, but on drift-aligned coasts wave climate variability can be a more important driver of shoreline stability through its control on longshore sand transport between compartments. Significant variability in the mean and storm wave climates along the south-eastern Australian coast, occurs on annual to decadal time scales. Wave climate shifts result in switching of sand transport paths on the shoreface and alongshore via headland bypassing, resulting in shoreline rotation. We use wave climate hindcasting, shoreface bathymetric change, and marine geoscience investigations to illuminate sand supply and transport processes for sections of the eastern Australian coast, over the past 120 years and 2,000 years. The centennial scale coastal evolution highlights the sensitivity of the east Australian coast to changes in wave climate and sand supply. On the medium term (to 2050 CE), wave climate variability and sand supply fluctuations, are likely to remain the primary determinants of shoreline recession, with monotonic or accelerating sea-level rise becoming an increasingly significant driver of shoreline change post 2050.