Morphology and Harbour Siltation at Cape Ferguson.

The Australian Institute of Marine Science (AIMS) facility at Cape Ferguson, in tropical North Queensland, carries out vital research into Australia's tropical Marine Estate. The facility is serviced by a harbour constructed forty years ago. Historically the harbour operated without major issues, however, in the last ten years, the harbour started to silt up, experiencing catastrophic rapid siltation since 2019 that closed the harbour. This paper examines the coastal processes of the region and quantifies sand transport at the site, ultimately using this to develop a permanent solution that works with the natural systems to preserve the coastal processes. The regional morphology is dominated by the Burdekin Delta and the sustained south-easterly winds and waves that drive the sediments north. With generally mild waves, in the lee of the barrier reef, and a large tidal range the coast consists of sand beach backed by cyclone-influenced dune lines above wide tidal flats that extend to below the tidal range before dropping away into deeper water. Cape Ferguson anchors the coast in this area with the coastline south of the cape accreting over thousands of years. Major weather events can drive rapid changes in coastal systems. Cyclone Yasi in 2011 resulted in the redirection of the ebb tide channel towards the harbour. Major floods in 2019 resulted in a further movement that drove rapid siltation in the lee of the harbour breakwater. A detailed understanding of the morphological processes was required to develop workable solutions. Utilising data captured by AIMS and numerical modelling tools the complex processes were defined and quantified. The following broad sand transport regimes were assessed: • On the beach to the North • Across the tidal flats to the West • In the ebb tide channels to the East • Around Cape Ferguson to the Northeast. [ABSTRACT FROM AUTHOR]