Navegando por Autor "TEIXEIRA, Sheila Gatinho"

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Acesso aberto (Open Access)
Análise de imagens de sensores remotos orbitais para mapeamento de ambientes costeiros tropicais e de índices de sensibilidade ambiental ao derramamento de óleo no Golfão Maranhense
(Universidade Federal do Pará, 2006-04-18) TEIXEIRA, Sheila Gatinho; SOUZA FILHO, Pedro Walfir Martins e; http://lattes.cnpq.br/3282736820907252
The oil spills in Brazil are more and frequents, causing several impacts on environments and biological communities. Envronmental sensitivy index maps of oil spils are indispensbles components of contingency and emergency answer plans for this tpe of accident. These maps present a system of classification based on geomorphologic characteristics of the áreas, which are defined by the following factors: wave and tidal energy exposure relative degree, shoreline slope and substrate type, and also, the easiness to clean and remove the oil impacted áreas. In this contect, the “Golfão Maranhense” region, located on Northern “Maranhão” State, was chosen in order to map and analyze the environmental sensitivity indexes (ESis) of oil spills on coastal environments, for in this área, we find the second largest port in draught of the world, the Porto f “Itaqui”. Moreover, this region is the route of six hundred oil tankers per year, which are potential agents that cause the oil spill. The methodological approach for creating the maps of environmental sensitivity index included the integrated analysis of coastal environments based on digital image processing from remote optical sensores, in this case, Landsat-4TM, CBERG-2 CCD and SPOT-2 HRV, SAR (Synthetic Aperture Radar) images from RADARSAT-1 Wide 1, SRTM (Shuttle Radar Topography Mission) elevation data, geographic information system and Field surveys related to geomorphology, topography and sedimentology. Using the aforementioned methods, the coastal environments recognized in “Golfão Maranhense” were grouped according to their envronmental sensitivity index: 1 – Solid men-made structures (ESI 1B); 2- Cliffs (ESI 1C); 3 – Fine grained sand beaches and móbile dunes (ESI 3ª); 4- Tidal sandflats (ESI 7); 5- Mixed intertidal Banks, tidal mudflats and ebb-tidal delta (ESI 9ª); 6- Supratidal sandflat (ESI 9C); 7- Saltmarshes (ESI 10ª); 8- Fresh marhes and intermittent lakes (ESI 10B) and 9- Mangrove (ESI 10C). This approach is efficient to recognize and analyze coastal environments and, therefore, it pernitted the sensivity index attribution for the oil spill on yhese environments, in a georefenced data base, which allows making faster e more efficiently decisions in case oil spills come to happen.
Acesso aberto (Open Access)
Mapeamento de ambientes costeiros tropicais (Golfão Maranhense, Brasil) utilizando imagens de sensores remotos orbitais
(2009) TEIXEIRA, Sheila Gatinho; SOUZA FILHO, Pedro Walfir Martins e
This paper presents the results of coastal environmental mapping of Golfão Maranhense, Brazil, using a methodological approach that includes: (a) integrated analysis based on digital image processing of Landsat-4 TM, SPOT-2 HRV, RADARSAT-1 SAR (Synthetic Aperture Radar) and SRTM (Shuttle Radar Topography Mission) data; (b) geographic information system; (c) field surveys related to geomorphology, topography and sedimentology. Mapped environments were grouped into four sectors: Sector 1, with salt marsh, fresh marsh, estuarine channel and intermittent lake; Sector 2, embracing coastal plateau, fluvial floodplain, sandflats, macrotidal beach, urban areas, artificial lakes and mudflats; Sector 3, including, paleodunes covered with grass, mangroves and mixed intertidal banks; Sector 4, constituted by mobile dunes. In addition, perennial lakes, ebb-tidal deltas and supratidal sandflats were recognized. Digital image processing visual analysis of orbital remote sensing data in association with geographic information system, proved to be effective in tropical coastal mapping, allowing the generation of products with good accuracy and cartographic precision.
Desconhecido
Radar de abertura sintética aplicado ao mapeamento e reconhecimento de zonas úmidas costeiras
(Universidade Federal do Pará, 2011-12-09) TEIXEIRA, Sheila Gatinho; SOUZA FILHO, Pedro Walfir Martins e; http://lattes.cnpq.br/3282736820907252
The use of SAR imaging to identify coastal wetlands under different acquisition configurations and different environmental conditions is a research topic at the forefront of knowledge in the field of remote sensing. In order to evaluate the potential of the use of SAR images in tropical coastal environments, an Environmental Protection Area of Baixada Maranhense was chosen to be investigated, given the state of preservation of the study area, where one can observe, mainly, mangrove ecosystems, fields salt marshes and fields flooded by fresh water. RADARSAT and ALOS PALSAR images in different imaging modes were acquired under different environmental conditions. In RADARSAT-1 Wide 1 images, it was possible to separate the mangroves and floodplains, in the dry and rainy seasons, especially when the images were acquired in conditions of zero precipitation, since with humidity in the system, the separation between these environments tends to decrease by the increase in backscattering. The influence of the high tide condition on the backscatter values of the RADARSAT-1 images was not verified. Contextual automatic classification based on frequency was able to separate mangroves from floodplains and water in both seasons from floodplains and water in both seasons. The RADARSAT-1 Wide and Fine images, acquired during the rainy season, under high rainfall, different tidal conditions and different incidence angles (20º - 47.8º) were transformed by the principal component analysis method, which attested that they are highly correlated. The backscatter analysis of these images showed a low separability for smaller incidence angles (20º to 31º), while in the images acquired at larger angles (41º to 47º) the separability is a little higher, when analyzing the mangrove environments and floodplains. In multipolarized RADARSAT-2 and PALSAR-HH images, acquired in the dry season, in areas of floodplain, saline and pasture grasslands, it was verified that the microtopography parameter HRMS, of the grassland areas, influenced about 49% of the values of σ0, of the image PALSAR-HH. For the RADARSAT-2 images, in the HV and VH polarizations, this influence was low, around 24% and 26%, respectively. In the parallel polarizations, the microtopography did not influence the zero sigma variations. Therefore, SAR images can be considered an excellent source of data for the recognition and monitoring of tropical coastal wetlands.