Abstract
Headland Bypassing is mainly a wave-driven coastal process that
interconnects sediment compartments and allows the continuity of the
longshore sediment transport. Waves, in turn, are subject to atmospheric
patterns and climate drivers. Hence, this study focuses on identifying
the atmospheric systems and associated wave conditions that have
triggered bypassing events in Fingal Head (New South Wales, Australia)
over the last 33 years. For this, clustering techniques were used to
identify 225 weather types that represent the daily atmospheric
variability over the Coral-Tasman Seas. Four recent storm events that
triggered headland bypassing were numerically simulated including waves,
currents, sediment transport, and morphological evolution in order to
identify the relevant weather types for the development of the sand
pulse. Results revealed that strong low-pressure systems (e.g., Tropical
Cyclones and East Coast Lows) occurring off the Eastern Australian coast
around 30°S are the dominant patterns triggering bypassing events in the
study area. The headland bypassing mechanism was observed to vary
between large sandbar systems and sediment leaking around the headland
according to slight changes in the sea states generated by these storm
events. Overall, atmospheric patterns showed control over when and how
the bypassing pulse occurs, whereas sediment availability is the main
factor influencing long-term cycles of bypassing that are subject to the
variability of El Niño – Southern Oscillation and Pacific Decadal
Oscillation. Altogether, this study emphasized the intricacy between the
multiple factors controlling headland bypassing events, which has direct
implications on the potential for predicting the occurrence of this
local coastal process.