Daniel Wishaw

and 4 more

Headland sediment transport is dynamic and complex, but understanding the transport mechanisms is necessary for effective long-term management of downdrift beach compartments. In this study, we have develop a coastal process model using TUFLOWFV, that is used to calibrate an approximation tool for headland bypassing at the study site. The approximation tool is shown to reproduce sediment transport rates at the headland apexes accurately and efficiently. We have explored the headland sediment transport mechanism, the influence of wave height and direction, and the sensitivity in regional climate conditions. Headland sediment transport is shown to occur as ‘trickle’ bypassing under modal wave conditions or ‘sand slug’ migration under storm wave conditions that travel in either a headland-attached and a cross-embayment pathway. Bypassing during storm wave conditions produces 50% to 60% of total bypassing volume, despite only accounting for 6% of the recorded days. The results indicate that headland transport is sensitive to changes in wave direction and wave height, with the existing mean wave direction balancing sediment transport on the east and north faces of the headland. Seasonality is the most significant climatic control on headland transport, while ENSO phase is only significant for the headland apexes that are exposed to south-east wave conditions. The potential for anticlockwise rotation of the wave climate in future is explored, with greater erosion of the northern beaches of the headland likely due to a reduced supply of sediment around the eastern point of the headland and greater erosive wave power on the north side.