ABSTRACT. 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.Keywords: coastal environments, wetlands, orbital remote sensing, images, Amazon Region. RESUMO.Este trabalho apresenta os resultados do reconhecimento e mapeamento dos ambientes costeiros da região do Golfão Maranhense, Brasil, utilizando uma abordagem metodológica que incluiu: (a) análise integrada com base no processamento digital de imagens,ópticas Landsat-4 TM e SPOT-2 HRV, de imagens SAR (Synthetic Aperture Radar ) do RADARSAT-1, e dados de elevação da SRTM (Shuttle Radar Topography Mission ); (b) sistema de informações geográficas; e (c) levantamentos de campo relativosà geomorfologia, topografia e sedimentologia. Os ambientes costeiros, assim mapeados foram agrupados em quatro setores:Setor 1, com pântanos salinos, pântanos deágua doce, lagos intermitentes e canal estuarino; Setor 2, abrangendo tabuleiro costeiro, planície de maré lamosa, planície fluvial, planície de maré arenosa, praias de macromaré,área construída e lagos artificiais; Setor 3, com manguezal, paleodunas e planície de maré mista; e Setor 4, constituído por dunas móveis. Além disso, foram também reconhecidos lagos perenes, deltas de maré vazante e planícies de supramaré arenosas. O processamento digital e a análise visual das imagens de sensores remotos orbitais, associados ao uso de sistemas de informações geográficas, mostraram-se eficazes no mapeamento de zonas costeiras tropicais, possibilitando a geração de produtos com boa acurácia e precisão cartográfica.Palavras-chave: ambientes costeiros, zonasúmidas, sensoriamento remoto orbital, imagens, Amazônia.

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An analysis was conducted of the change in the shoreline in the northern part of Pará (Amazonian coast, Brazil) over a medium-term period. The analysis of the variation of the shoreline was carried out by tracing the spring high tide level in LANDSAT images from 1988 to 2019. With this tracing, it was possible to verify the behavior of the processes of erosion and accretion in the different morphological units (mangroves, beaches, cliffs, and rocky shores). The results show that changes in the shoreline occurred differently in the four morphological units, both in spatial and temporal scales. Regionally, the northern coast of Pará showed a trend of stability between losses and gains in areas, but with a slight predominance of the accretion process. The mangroves and beaches showed periods of alternation of predominance between the processes, while in the stretches with cliffs, the smallest areas of retreat were detected. The stretches of shoreline with a rocky shore remained stable throughout the study period. The study allowed the identification of local geoindicators for diagnosis and identification of the erosion process in coastal macrotidal regions. These results can assist in the identification of areas at risk of coastal erosion, as well as in coastal management in Pará State and related areas.

In the Amazon region, there are more than 26.000 people living in areas at risk of fluvial erosion processes. In addition to the large number of people impacted, studies have shown that the erosion patterns identified on the margins of mega rivers in the Amazon region are distinct due to the fact they are related the mass movement leading to great soil displacement known as ‘Terras Caidas’. In this context, this study aims to evaluate quantitatively the degrees of risk in areas subject to fluvial erosion in three communities: Itanduba, São Braz, and Fátima de Urucurituba. The methods include hazard attributes, as well as vulnerability aspects, through the Analytic Hierarchy Process (AHP). A multitemporal analysis were made to validated the marginal erosion at the studied areas. The results indicated a high risk of fluvial erosion on these areas. The local families lives under high and very high social vulnerability in conditions with little infrastructure and very close to the susceptible erosive riverbank. The riverbank is composed of poorly consolidated sediments, show instability indicators, and are usually associated to drainages with flow rates above 100.000m3/s. The results and methodology brings an important contribuition to territorial planning of the region.