Executive Summary
This study investigates infragravity (IG) waves on a steep-sloping, rough rocky seabed off China Rock, CA, comparing their dynamics to those on sandy shores and coral reefs. It finds that IG waves are predominantly free waves, with bound-wave contributions increasing significantly during storm events. The rocky shore environment leads to lower relative IG-to-sea-swell energy and minimal reflection, suggesting local generation and dissipation.
Why It Matters
Understanding wave dynamics in complex coastal environments, particularly rocky shores, is crucial for naval operations, coastal defense infrastructure planning, and predicting littoral zone changes that can impact amphibious landings or maritime security.
Key Takeaways
- Infragravity (IG) waves on rocky shores are primarily free waves, with bound-wave energy constituting less than 10% during low-energy conditions.
Source evidence · PDF page 18
During low‐energy wave conditions, r2 is typically less than the temporal and spatial mean of 0.1, indicating that less than 10% of the observed IG energy is phase‐locked to the SS wave groups and that the IG field is overwhelmingly composed of free waves.
- During storm events, IG waves exhibit increased bound-wave characteristics and propagate shoreward, following linear dispersion.
Source evidence · PDF page 16
In summary, phase‐difference spectra indicate that IG waves are predominantly shoreward‐propagating and progressive, following linear dispersion under non‐storm conditions and exhibiting increased bound‐wave relationships under storm conditions (e.g., Bertin et al., 2020).
- Rocky shores, unlike sandy beaches, show minimal IG wave reflection, indicating that IG waves are predominantly locally generated and dissipate without significant trapped wave contributions.
Source evidence · PDF page 24
The results suggest that IG waves in this environment are locally generated and either propagate freely and progressively or, during storms, prop
Strategic Relevance
This research provides fundamental insights into oceanographic processes in complex coastal environments, which is vital for naval planning, coastal engineering, and understanding the impact of wave energy on littoral zones relevant to defense operations and infrastructure.