Coastal Erosion at Pau Amarelo Beach, Northeast of Brazil

Abstract

This article concerns the erosion at Pau Amarelo Beach in Pernambuco, Brazil. The maintenance of this beach is important for tourists and the community and is significant for the local economy. Pau Amarelo is a highly urbanized area with poor coastal plain. The coast is characterized by the presence of lined reefs running along the shore. In order to understand the causes of the erosion at this site, coastline variation, the displacement of urban areas and wave characteristics were analyzed. It is believed that both the human incursions on the backshore and the intensification of longshore currents in some parts of the coast, caused by wave diffraction at the reefs, contribute to the beach erosion. The breakwaters built south of Pau Amarelo are also believed to decrease sediment transport by blocking the drift current. Beach nourishment is suggested as the most suitable solution to the erosion at Pau Amarelo. ADDITIONAL INDEX WORDS:Beach erosion, anthropic effects, numerical wave modeling, coastal hydrodynamic, longshore currents.

Understanding the impact of hydrodynamics on coastal erosion in Latin America: a systematic review

“…In the South American region, numerous studies have identified wave action as the main cause of coastal erosion. High-energy waves, the angle of incidence on the coast, and transformations caused by natural obstacles (such as islands and coral reefs), as well as artificial obstacles (such as breakwaters or seawalls) and bathymetry, have a severe and short-term impact on sandy beaches (Gomes and Da Frontiers in Environmental Science frontiersin.org Martins and Pereira, 2014;Fernandino et al, 2018). Variability in wave direction and intensity due to seasonal climate changes can amplify erosion and accretion processes in the area, especially during extreme events like storms or hurricanes.…”

“…These areas where small-scale changes in bathymetry occur are known as "bathymetric lenses," a concept proposed by (Speranski and Calliari, 2001), referring to areas on the seafloor with convex characteristics that act as lenses. Additionally, the presence of artificial reefs can also alter wave direction and increase energy in specific coastal areas (Gomes and Da Silva, 2014;Martins and Pereira, 2014;Fernandino et al, 2018). These areas where wave energy is concentrated on the coast are called "focuses of surf" a concept proposed by Glushkov in 1935 and often associated with erosive phenomena or changes in coastal morphology (Speranski and Calliari, 2001).…”

“…Coral reefs can increase wave energy and coastal currents, even when they are not directly in front of the beach, as in the case of Garapuá and Moreré (Elliff et al, 2019). In the state of Bahia, areas of erosion have been identified due to the presence of coral reefs, such as Pau Amarelo Beach and Porto Seguro (Martins and Pereira, 2014;Fernandino et al, 2018). A notable case is Candeias Beach, where the formation of reefs off the coast created an opening known as "Abreus Bar," which generated a deepwater channel and exposed the beach to high sediment transport.…”

“…WAPO, COCO and MATO models are also used to analyze the transformation of waves during their propagation. The WAPO model calculates the linear propagation of waves, and consequently the output of this model is used as input in the COCO or MATO model that solves the nonlinear equations in shallow waters (Silva-Casarin et al, 2012;Mallmann and Pereira, 2014;Martins and Pereira, 2014;Escudero-Castillo et al, 2018). For the calculation of coastal currents and sediment transport, the LITDRIFT model from MIKE Zero Software is used.…”