Search

Este trabalho apresenta resultados da classificação morfodinâmica de praias de enseada do Estado de Santa Catarina (158 praias, do Cabo de Santa Marta à Ilha de São Francisco do Sul) e do Litoral Norte do Estado de São Paulo (133 praias, da Baía de Santos à Ubatuba), realizada indiretamente através de interpretação de imagens aéreas. Para isso foram construídos mosaicos georeferenciados com imagens do satélite QuickBird2 (para o Estado de Santa Catarina) e com fotografias aéreas verticais (para o Litoral Norte do Estado de São Paulo). Nas imagens foram analisadas a extensão das zonas de surfe e de espraiamento, presença de bancos, correntes de retorno e cúspides. Praias dissipativas apresentaram zonas de surfe e espraiamento extensas (> 100 m) e presença de sistemas de bancos múltiplos. Nas praias intermediárias foi observada uma extensão moderada das zonas de surfe (até 100 m) e espraiamento (até 10 m), além da presença de bancos rítmicos, correntes de retorno e cúspides. Já nas praias refletivas foi observada a ausência de zona de surfe (com a quebra de ondas ocorrendo na face da praia), zona de espraiamento estreita (< 10 m) e presença de cúspides. No Estado de Santa Catarina foi observado o domínio de praias refletivas. Essas praias dominam as regiões abrigadas, mas também ocorrem em locais expostos e com sedimento grosso. Seu domínio ocorre associado às baías Norte e Sul de Florianópolis, além da região da Costa Brava (da praia de Mata Camboriú à de Taquaras/Taquarinhas), que é exposta a ondas de maior energia. Praias intermediárias e dissipativas ocorrem predominantemente em regiões expostas. No Litoral Norte do Estado de São Paulo houve um equilíbrio entre praias refletivas e dissipativas. As praias refletivas tendem a dominar as regiões abrigadas (e.g. Canal de São Sebastião), mas o tamanho do sedimento disponível parece ser mais importante na determinação do estado morfodinâmico das praias protegidas, uma vez que também ocorrem praias dissipativas nesses locais. As praias intermediárias apresentam-se sempre em locais expostos. Observou-se a coincidência de mais de 70% da interpretação das imagens das praias do Estado de Santa Catarina e do Litoral Norte do Estado de São Paulo com dados de campo disponíveis na literatura. Conclui-se assim que a interpretação de imagens aéreas é um excelente método para determinar indiretamente o estado morfodinâmico de praias de enseada, desde que se tenha boas imagens e um interprete treinado e com experiência.

The main objective of this work was to describe the morphologic variation at Itapocoroi Bay – SC, and to identify the development of an erosional hot spot, through the comparison of beach profile data taken before and after the beach nourishment project done by the year of 1999, with the monthly topographic survey obtained at 2008. The results show that the beaches have distinct morphologic behavior due to the increase in the wave energy exposition of the shore. The south portion of the bay is more sheltered, and has flat beach profile slopes (between 2o and 3o) while the northern part, more exposed, shows steeper slopes (5o to 7o) and scarped profiles. Nine years after the nourishment project completed at Picarras beach, approximately 50% of the sediment volume was lost, especially at the south end next to the river, where there is a well developed hot spot, which shows rates of volume loss of about 95%. The survey also shown that there is no significant alongshore sediment transport to the north, what reinforces the idea that the cross-shore transport has importance at the erosional process.

This work has applied an integrated method for defining set-back lines associated with coastal hazards on sandy shores for a 50-year period of interest. This method is based on the shoreline evolutionary trend being the basis for the first set-back line determination. Afterwards the set-back line were adjusted by incorporating changes associated with the acceleration of sea-level rise and the evaluation of the consequences (instantaneous shoreline retreat and potential flood zone) of an extreme storm. The study area was Itapocoroi Bay, in northern coast of Santa Catarina State, southern Brazil. The determined set-back lines were plotted over rectified aerial photographs, allowing for a straight-forward interpretation of results. The segments northward of Picarras river mouth and right before the Itajuba headland were the most susceptible zones due coastal hazard mentioned. The integrated method showed to be an important tool for coastal management since it adopts a worst-case scenario approach.

For the last ten years new offshore oil fields were brought into production in the Santos Basin. This has led to an increase in the processing and transportation of crude oil and its derived products, hence posing new threats to the integrity of coastal environments and human resources. The Brazilian Ministry of Environment responded by coordinating an initiative aimed at mapping the sensitivity to oil spill of the Brazilian coastline. The results for the Santos Basin are presented here, for which the appropriate technologies had to be integrated in order to cover over 1300 km of the coastal environment. A partnership between public and private sectors was established in order to achieve high-quality mapping standards by sharing data and expertise. A total of ten ETM+ Landsat images have been mosaicked and processed using spectral image techniques such as restoration and band fusion. Remote sensing and field data have been organized into a digital database following an object-oriented model devised to allow the retrieval and upgrading of spatial and tabular data. These procedures are now standard practices for mapping the sensitivity to oil spill of other marine basins in Brazil. A total of 44 maps have been produced in three different geographic scales for specific contingency planning and spill scenarios. Parana state has 82% of its coastline occupied by mangrove vegetation, the most sensitive ecosystem. In contrast, 52% of the Rio de Janeiro coastline are composed of different types of rocky shores, from vertical impermeable substrates to thalus deposits. Rio de Janeiro also has the largest proportion of sandy substrates, with 41% of its coastline. Many other diagnostic information and quantitative analyses can be carried out by querying the available geographic database, which are necessary for any contingency planning and emergency response actions.

The Littoral Sensitivity Index (LSI) is based on geomorphologic characteristics as the exhibition degree to the energy of the waves and tides, the steepness of the coast and the substratum type, fundamental for the determination of the impact degree and permanence of the spilled oil. Each LSI represents the sensibility of a space of the coast, and it varies of the least sensitive (1) to the most sensitive (10). The sensibility maps consist of contingency plans in case of oil spill, and could impede or reduce the caused impacts to the coastal zone. The present work had for general objective to determine the LSI to the spill of oil for southeast and south area of the State of Santa Catarina in order to integrate the project SAO Letters. For obtaining the necessary characteristics, data originated from the project SAO Letters and “field survey” was used. Later they were organized in GIS, to be classified in agreement with the proposed methodology. The computational tool used was the software ArcMap version 8.3. The resulting LSI maps are articulated in 15 Operational Maps at 1:50.000 scales. In the study area 87 segments were identified, totalizing 819,82 Km of extension. The applied methodology showed to be efficient for visualization and determination of the characteristics that distinguish different LSI.