Navegando por Assunto "Coastal erosion"

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Acesso aberto (Open Access)
Os efeitos dos manguezais e das intervenções humanas na dinâmica sedimentar das praias de SalinópoliS, PA
(Universidade Federal do Pará, 2025-03-07) PÉREZ MARTINEZ, Julián David; COHEN, Marcelo Cancela Lisboa; http://lattes.cnpq.br/8809787145146228
Salinópolis, on the coast of Pará, has become an important tourist hub, expanding its infrastructure along the coastal zone. This area is considered sensitive to sea-level rise. Therefore, identifying the area most vulnerable to coastal erosion is extremely important, especially due to the growth of coastal urban areas, which can interfere with sediment balance, intensifying erosion processes. This master's thesis aims to identify the effects of mangroves and coastal urban expansion on sediment balance along the beaches of Salinópolis. This study was carried out through a spatio-temporal analysis based on satellite (2003 – 2023) and drone data (2019-2024). The data revealed that the urban area expanded (627 ha), while the mangrove area fluctuated, increasing from 3630 ha to 3889 ha between 2003 and 2023. Erosion was identified along the beaches, particularly at Praia do Farol Velho (erosion = 432,625 m³, sedimentation = 217,259 m³). Praia do Atalaia (erosion = 115,415 m³, sedimentation = 462,630 m³) and the Maçarico/Corvina beaches (erosion = 640,389 m³, sedimentation = 801,670 m³) showed a trend of sediment accumulation. Erosion has predominantly occurred in the lower intertidal zone, while sedimentation has occurred in the supratidal zone and the upper intertidal zone. Residences, particularly in Farol Velho, may accentuate this process and Praia do Atalaia, which are currently located in the intertidal and supratidal zones in front of the mangroves. The walls built to protect these residences from waves and current action have also functioned as a barrier to retain sediments at the upper intertidal/supratidal transition. In much of Praia do Farol Velho, without these walls, there has been erosion in the intertidal zone, with a retreat of the coastline by about 100 meters between 2009 and 2023. However, the Maçarico/Corvina beaches have mangroves in front of the urban infrastructure, with sediment accumulation predominantly in the supratidal zone and the upper part of the intertidal zone. Human interventions on these beaches have not impacted the sedimentary dynamics until 2023. This beach provides a good example of how coastal infrastructure projects should be planned, using mangroves as protection against the action of waves and currents. However, the construction of beach access walkways in 2024 altered the hydrodynamic flow of a tidal channel, trapping tidal waters and creating muddy intertidal zones with porewater salinities close to 70 ‰. This process has already killed approximately 7 ha of mangrove. These data provide valuable insights to guide more efficient public and private investments, avoiding construction in high-risk areas or those that harm the mangroves, offering crucial information about coastal erosion and its impacts on urban infrastructure in the beaches of Salinópolis, especially in the face of sea-level rise.
Acesso aberto (Open Access)
Mudanças morfológicas em praias da costa Leste da ilha do Marajó e os níveis de vulnerabilidade à erosão
(Universidade Federal do Pará, 2021-06-29) SOUSA, Maria Bárbara Pereira de; RANIERI, Leilanhe Almeida; http://lattes.cnpq.br/3129401501809850; https://orcid.org/0000-0002-9870-4879
The coastal zone is a transition area between the sea and the continent, being one of the most vulnerable geographic spaces on the planet. In view of this, the assessment of morphological changes and coastal vulnerability to erosion is essential, as it contributes to the planning of protective and mitigating actions against impacts that occur on the environment, whether natural or anthropic. Thus, the work aims to verify the morphological changes in beaches on the east coast of Ilha de Marajó/PA and their levels of vulnerability to erosion at different time scales. For this purpose, two field campaigns (dry and rainy seasons) were carried out at Barra Velha beach (municipality of Soure) and Praia Grande (municipality of Salvaterra). The methodology consisted of a semi-quantitative analysis, determined by parameters of human and natural occupation evaluated on the beaches. Remote sensing techniques (medium period data) and in situ data collection (short period data) were used. According to the results obtained, Barra Velha beach was classified as dissipative in the two periods studied and most profiles topographic showed an erosive trend from the dry to the rainy period. Praia Grande showed behavior of intermediate to reflective beaches in both the dry and rainy seasons. The sedimentary accretion phase of this beach occurred during the rainy season, reflecting an atypical pattern for beach morphodynamics. Barra Velha beach exhibited moderate erosion vulnerability in the northwest sector and high vulnerability in the southeast sector, mainly due to the high erosion rate over the 16 years studied. Praia Grande, on the other hand, presented a moderate degree of vulnerability to erosion, being considered a more stable beach, combined with coastal protection works. On both beaches, the coastal risk was low due to the low level of occupation close to the coastline. It is believed that the results of this research can contribute to future studies on the theme of vulnerability to erosion in areas that are little or very anthropized and, for possible actions of coastal management in the Amazon region, considering their environmental particularities.