Analysis of the Hydrodynamics and Morphological Changes of the Gold Coast Seaway Ebb-Tidal Delta

Abstract

The Gold Coast Seaway (GCS), known as the Nerang River Entrance (NRE) prior to stabilisation, is located at one of Australia’s premier tourist centres, and consequently, the provision of a safe navigation channel is significantly important for recreational boating and commercial craft activities between the ocean and the estuary. The tidal regime in the area is semi-diurnal with neap and spring tidal ranges of 0.3m to 2m respectively, and the entrance has a minor ebb dominant current regime. The dominant offshore wave climate is south to south east, and the beaches have a wave dominated, double bar morphology. The entrance location had undergone drastic changes due to natural processes prior to its stabilisation in 1986. These changes were significantly influenced by the dominant northward wave condition which, in combination with the resultant longshore sediment transport (LST), resulted in the entrance’s net northward migration prior to the stabilisation. The entrance has experienced an alteration in the inlet tidal prism since stabilisation and the implementation of the artificial bypassing system. As a result, the extent of the ebb-tidal delta offshore and its equilibrium volume have changed.