Extreme storm events drive beach connectivity through headland bypassing

Area of Science:

• Coastal geomorphology
• Oceanography
• Meteorology

Background:

• Headland bypassing is a key wave-driven process connecting coastal sediment compartments.
• Wave dynamics are influenced by atmospheric patterns and climate drivers.
• Understanding these drivers is crucial for coastal management.

Purpose of the Study:

• Identify atmospheric systems and hydrodynamic conditions triggering headland bypassing at Fingal Head, NSW, Australia over 33 years.
• Analyze weather types and storm event characteristics influencing sand pulse development and bypassing mechanisms.

Main Methods:

• Applied clustering techniques to classify 225 weather types from Coral-Tasman Sea data.
• Modeled four major storm events, simulating nearshore waves, currents, sediment transport, and morphological changes.
• Linked specific weather types to bypassing events and analyzed sea state variations.

Main Results:

• Strong low-pressure systems (Tropical Cyclones, East Coast Lows) off eastern Australia are dominant triggers.
• Bypassing mechanisms varied (sandbar system vs. sediment leaking) based on storm tracks and sea states.
• Atmospheric patterns dictate the timing and nature of bypassing pulses.

Conclusions:

• Atmospheric patterns control short-term bypassing events, while sediment availability drives long-term cycles.
• Coastal interconnectivity and management planning require understanding the interplay of atmospheric drivers and sediment dynamics.
• This study highlights the complex factors governing headland bypassing.