Analysis of landslides susceptibility and use and landcover evolution of Paraty City - RJ / Análise da suscetibilidade a escorregamentos e as implicações da evolução do uso e cobertura do solo no município de Paraty, RJ

AUTOR(ES)
DATA DE PUBLICAÇÃO

2010

RESUMO

The city of Paraty is located between the Angra dos Reis and Ubatuba municipalities, stages of a numerous episodes of landslides. As the neighboring cities is marked by the presence of the Serra do Mar, where the shallow landslides in the form of translational movements account for most of the evolution of relief. And yet, there is no reference to deaths associated with these accidents, relatively numerous in the two neighboring cities. The research aimed to make a to landslides susceptibility map (SE) of Paraty municipality, helping the local government in planning the future soil use and occupation. This map, with three classes of susceptibility (low, medium and high) was the result of crossing, in a GIS environment, of the use and land cover (image data of orbital remote sensing and field information), lithologies, geological structures and slope and curvature maps. We tested three different digital elevation models for the development gives maps of slope and curvature: SRTM and ASTER resampled to 30 m spatial resolution and ASTER 15 m spatial resolution, which was adopted by the distribution of more reliable areas relating to different classes of susceptibility. In the absence of reliable rainfall and suitable for research, was considered, for an exercise to demonstrate the importance of the parameter, data from the Civil Defense of Paraty, supplemented by data from surrounding areas (DAEE-SP and Management Plan of the National Park of Bocaina) and the map of isohyets from Bazilian Geological Service (CPRM). In the field, by land, sea and air was observed the use and land cover and localized slip scars. Whereas there are orbital images from the end of the isolation of Paraty, in 1975, resulted in the development of forested areas in the municipality interpreting orbital images of the years 1973, 1986, 1993, 2000, 2007 and 2008. The maps thus generated were crossed with the other parameters given by the natural conditions of land, evidently stable in the period, enabling them to get maps of SE over 35 years and their evolution over time. The analysis of this trend is worrisome because it shows that human occupation in areas of high susceptibility increased 4.8% per year. The results classify 34% of the municipal area as low susceptibility, 53% as medium and 13% as high. Note that between 1973 and 2008 23% of forests were lost, with an average annual loss of 0.6%, more pronounced during the opening of the BR-101(which is inevitable) and from 2000 (which is worrying). It follows that the population lives, especially the areas of low susceptibility to landslides while the areas of medium and high sensitivities without forest cover dominated pastures. Although the prospects worry, this study shows a future risk, just in time to be minimized and / or avoided. Considering the rural and urban sprawl as inevitable, a Master Plan to consider the susceptibility to mass movements is essential.

ASSUNTO(S)

paraty escorregamentos movimentos de massa landslides mass movement paraty

ACESSO AO ARTIGO

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