Coastal Storm Events and Associated Impacts on Oceanic Beaches Between Ilha Grande and Cabo Frio (RJ, Brazil)

Understanding the impacts of storms on coastal environments, particularly on sandy beaches, is highly relevant due to their vulnerability to erosion during such events. This research compared two distinct parameters, Storm Power Index (SPI) and Wave Energy Flux (WEF), to identify, quantify, and classify coastal storm events based on the behavior of gravity waves. The investigated region comprises all oceanic beaches between Ilha Grande and Cabo Frio, in the state of Rio de Janeiro, SE Brazil, spanning over 200 km of coastline. During the investigated period (1986–2018), over 400 storm events were identified, presenting a clear interannual variability, mostly marked by energetic events in La Niña years. The four most energetic episodes were studied in detail in terms of wave setup, near-bottom orbital velocity, and net shoreline movement. It was found that these episodes induced sediment remobilization between the coastline and the 30 m isobath, leading to retreat in more than 80% of the study area’s coastline. Finally, the WEF parameter was found to be more consistent than the SPI for this kind of study as it physically represents the amount of energy transferred from the ocean waves to the coast.