This paper presents a new approach of landslides zonation hazard studies, based on an integrated study of structural data along with geomorphological and external factors, in a hilly regions of Brazil, covered by a tropical humid rain-forest, called Serra do Mar. The Serra do Mar consists of a hilly region along the east coast of Brazil, with high slopes and many geological structures in a gneiss -migmatitic terrain. In contrast to traditional approaches, this method proposes that structural data (foliation, fractures and bedding planes) and its relation with the slope geometry, is important to be consider in the landslide zonation hazard, along with declivity, relative relief, soil and rock properties, land use and vegetation cover and hydrogeological and climate factors. Results show that slopes with high hazard have the same dip direction of geological structures. Landslide zonation hazard using structural data contributes to a better understanding of how these structures, preserved in tropical residual soils, influence on slope stability and generates landslides.
The geo-environmental zoning represents an important strategy in the territorial management. However, it requires a logical and structured procedure. Therefore, an approach using physiographic compartmentalization is proposed and applied as case study in a region covered by the topographic maps of São José dos Campos and Jacareí, Brazil. This region has great geological and geomorphological peculiarities, beyond being a place with large human interventions because of its quickly economic growth. The methodology is based on photointerpretation techniques and remote sensing in GIS environment. As a result, seven geo-environmental zones were obtained from a weighted integration by multicriteria analysis of physiographic units with land-use classes. In conclusion, taking into account potentialities and limitations, the proposed approach can be considered able to support sustainable decision-making, being applicable in other regions.
O objetivo deste trabalho é de discutir os resultados obtidos pela análise temporal da ocorrência de movimentos de massa em Caraguatatuba e São Sebastião (SP), entre 1967 e 2011, através da fotointerpretação de cicatrizes de escorregamento e levantamento bibliográfico. Para tal, foram utilizadas cartas topográficas em escala 1:50.000 do IBGE das folhas Caraguatatuba, Pico do Papagaio, Maresias e São Sebastião, mapa geológico em escala 1:50.000 das folhas Caraguatatuba e Pico do Papagaio e São Sebastião, ortofotos em escala 1:10.000 da Emplasa (2011) e mapa de cicatrizes de escorregamento (FÚLFARO et al., 1976). Em ambos os cenários os locais mais atingidos por movimentos de massa foram aqueles situados na região serrana, devido às suas características fisiográficas (altos valores de declividade, relevo escarpado a serrano e existência de canais de primeira ordem). Estes resultados serão utilizados para subsidiar estudos de retro-análise e como inputs para modelagens numéricas com softwares de simulação 3D. Palavras chave: Movimentos de massa, Cicatrizes de escorregamento, Retro-análise, Ortofotos 1. Introdução Movimentos de massa são processos dinâmicos que ocorrem, em geral, em vertentes. Esses eventos podem ser desencadeados pela interação entre diferentes fatores endógenos, tais como tipo de solo, de rocha ou de forma do terreno, e fatores exógenos, como variáveis climáticas, fatores antrópicos, entre outros (BISPO et al., 2011). Os movimentos provenientes dessas interações correspondem ao
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