Generation and Dissipation of Infragravity Waves Over Natural and Engineered Chenier Plain During Hurricane Laura

Abstract Infragravity (IG) waves play a crucial role in nearshore hydrodynamics and sediment transport; however, their generation and dissipation mechanisms during extreme storms remain challenging to assess due to limited data availability, site‐specific characteristics of natural landscapes, and anthropogenic effects. This study investigates IG wave generation and dissipation in the Rockefeller Wildlife Refuge, part of the Chenier Plain (CP) in southwestern Louisiana, USA, during Hurricane Laura (2020). Field observations from eight pressure transducers, deployed along two cross‐shore transects, are complemented with numerical modeling to examine IG wave behavior under a major hurricane. Three distinct storm stages are identified: rising water, inundation, and receding water. Bound long waves were the primary source of IG energy when the area was fully inundated at both transects. Wave refraction and reflection related to geometry‐trapping contributed to IG wave convergence during the rising water stage at the breakwater‐protected shoreline. Wave breaking caused significant IG energy dissipation over the shore, whereas vegetation drags induced most wave attenuation in wetlands. Numerical results indicate that low‐crested breakwaters block onshore propagation of incoming waves but may also amplify IG waves at the protected shoreline. Compared to the natural shorelines, breakwaters can enhance IG wave energy, potentially prolonging flooding and sediment transport. In contrast, wetlands effectively dissipate IG waves, reducing flood impacts. These findings improve our understanding of IG wave dynamics in engineered and natural coastal systems, contributing to the enhancement of hurricane impact modeling and coastal resilience strategies.