Influência de estruturas artificiais na dinâmica costeira em praias de João Pessoa/PB

Abstract

This study analyzes the coastal shoreline dynamics and the processes of erosion, stability, and sedimentation, establishing a connection between natural and artihropogenic aspects along Seixas and Cabo Branco beaches, in Paraiba State (Brazil). The research hypothesis assumes that the beach morphology and sedimem budget of these areas are influenced by rigid artificial structures built along the shoreline. Thus, the aim of this stady was to analyze the influences of rigid trtificial structures on the local hydrodynamic and morphosedimentary processes of Seixas and Cabo Branco beaches in João Pesson-PB. To achieve these goals, the following methodological procedures were adopted: (1) monitoring four transversal topographic profiles (P1 to P4) along the shadied beaches over a 13-month period to observe beach morphology dynamics; (2) quantifying sediment balance during the study period across the four transversal profiles, (3) estimating shoreline changes through a multitemporal analysis (2016-2024) using the CASSIE platform, and (4) Atalyzing marine hydrodynamics using the SMC-Brasil model for the period from 1948 to 2008. The results showed that profile P1 (near Cabo Branco viewpoint) presented slight accretion (3.38 m³/m), probably due to wave reflection generated by the nearby structure: profile P2 (near the Cabo Beatco cliff), a sector with riprap, also showed mild accretion (2.06 m³/m), profile P3 (located on the sandy point of Seixas bench) recorded higher accretion (8.60 m²/m), whereas profile P4 (the southernmost profile) exhibited accelerated erosion (-9.04 m/m). Regarding shoreline changes, the northern portion of Cabo Branco beach (transects 9 to 50) was characterized by stability or accretion, while transects 51 to 105 (southern portion) showed a predominant erosive trend. Transects 115 to 117 (the sandy point at the northern part of Seixas bench) displayed a tendency toward accretion. In contrast, iransects 106 to 114 and 118 to 147 (central and southem portions of Seixas beach) were predominantly stable to accretion. As for marine hydrodynamics, the results indicate that during periods of higher meteorological energy, such as winter and spring, currems, winds, and waves become more effective, producing higher sediment transport rates. However, the mean transport/flow outputs geherited by the SMC model revealed predominantly negative sediment transport values across four of the five transversal profiles, except for profile 4, which remained positive throughout all analyzed periods. In summary, the findings highlight the complexity of this coastal environment, which is constantly changing depending on natural energy variations, as well as athropogenic interferences that restrict natural sediment mobility, thereby generating or intensifying several envirımmental problems in the area.