Nearshore Wave Power Increase on Reef‐Shaped Coasts Due to Sea‐Level Rise

Abstract

AbstractLarge parts of tropical coastlines are influenced by the presence of reefs that shape its coastline. Wave attenuation crossing reefs as they approach the coast results in accretionary coastal features developed in its shadow zones. With the aim of assessing the level of wave exposure of the coastline under different sea‐level rise scenarios, numerical modeling experiments have been designed considering a coastline segment of approximately 450 km in northeast Brazil. Results show the distribution of wave power along the area of interest, with higher values being found in areas without reefs. However, when considering sea‐level rise scenarios, it is behind the reefs where the maximum differences in wave power are observed. The increase in the free surface over the reef structures as a result of rising sea level reduces the wave attenuation effects caused by these structures. Thus, the waves hit the shore with greater force in the shadow zone protected by the reef. Here, we demonstrate that regions within the reef shadow zones are most strongly affected by sea‐level rise with up to a 90% increase in the wave power, which will lead to increase in sediment transport and erosion processes. Such processes indicate a trend toward coastline flattening and alignment in response to less effective shadow zones.