Ben Williams, Lex Nielsen, Will Glamore, Duncan Rayner, Francois Flocard, David Williams

This paper presents an innovative and detailed dataset of currents and sediment transport observations over a sand shoal system responsible for focusing wave energy on eroding coastline. The data are used to measure the performance of a detailed numerical sediment transport model of the sand shoal system. The predictive skill of the model is 0.96 for tidal elevations within Port Phillip Bay, 0.75 for tidal currents over the shoals, and 0.80 for bedload transport. Analysis of available bathymetric data suggests the sand shoal system exhibits large-scale mobility over unexpectedly short timescales, which must be driven by exceptionally strong tidal currents. Simulated residual bedload estimates are of the order of 5,000 m3/ m / annum over the crest of the bank and are highly ebb-dominant. The data and calibrated model system will be used as a tool to inform the efficacy of various coastal management options at Portsea.