Intense coastal sedimentation and erosion in the Cananéia outlet, Southern State of São Paulo, Brazil

• Published in: Boletim do Instituto Oceanográfico 1983, Vol.32 (1), p.71-75
• Main Authors: SUGUIO, K, TESSLER, M. G
• Format: Article
• Language: eng ; por
• Subjects: Earth sciences; Earth, ocean, space; Exact sciences and technology; Marine; Marine and continental quaternary; OCEANOGRAPHY; Surficial geology
• ISSN: 0373-5524; 0373-5524
• DOI: 10.1590/S0373-55241983000100007

The extreme mobility of submerged sand bars at the mouth of the Cananéia outlet has made safe access difficult to the lagoonal region of Cananeia, on the southern coast of the State of São Paulo. This problem is serious enough to have been treated by various authors over the past thirty years. Erosional and depositional processes in the area are the result of the combined very often conflicting action of tidal currents, waves, and longshore currents that are active in the dispersal of the sand sediments. Thus, at the time that processes of accelerated sedimentation occur at the mouth of the outlet intensive erosional phenomena act upon neighboring salient features of the coastline, such as Ponta do Perigo on Ilha do Cardoso and Ponta da Trincheira on Ilha Comprida. Comparative analysis of aerial photographs taken in 1962 and 1973 and of some bathymetric profiles allowed us to evaluate the evolution of the erosional process on the eastern side of Ilha do Cardoso during this period interval and to determine the growth tendency of the sand bars in the Cananéia outlet. A Barra de acesso a região lagunar de Cananéia-Iguape, na sua porção mais ao sul (Barra de Cananéia), possui bancos arenosos submersos, que através dos tempos tem apresentado extrema mobilidade, dificultando, assim, o acesso de embar cações a essa região. Processos erosivos e deposicionais atuantes nas regiões vizinhas a Barra, conjugadas as ações conflitantes das correntes de mares, ondas e correntes de deriva litorâneas, ocasionam a ativa dispersão dos sedimentos arenosos. A analise comparativa de fotografias aéreas obtidas em 1962 e 1973 permitiu avaliar as tendências erosivas e deposicionais das margens da Barra de Cananéia, bem como a tendência de crescimento dos bancos arenosos submersos.