Estuarine Beach Morphology in Microtidal Middle Harbour, Sydney



Microtidal Middle Harbour, Sydney, contains a range of estuarine beach morphologies from steep reflective beachfaces to wide low-tide terraces. The most exposed beaches are morphologically similar to lowest-energy open-ocean beaches; however, the remainder of the profiles cannot be adequately explained by established beach morphodynamic models. Estuarine beach morphology in Middle Harbour appears to be primarily influenced by storm events. Deep-water ocean waves rework profiles in the lower part of estuary. For beaches protected from these waves, tidal fluctuations are the main determinant of beach profile. Locally-generated wind waves are only a significant energy contributor where the fetch is large enough; however, this only occurs on two beaches where low-tide terraces are formed.