997 resultados para Erosão de praias
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This study aims to perform the morphometric characterization of the watershed stream Petiço, Botucatu-SP, through techniques of GIS by GIS IDRISI Selva and Charter planialtimetric Botucatu (SF-22-ZB-VI-3) , edited by IBGE (1969), scale 1: 50000 for ranking the drainage network and the morphometric analysis. The variables analyzed were the dimensions, the relief pattern, pattern of the drainage network and the shape variables. The results show that related to how the watershed has an oblong shape with environmental interpretation with low tendency to flooding and erosion. The sinuosity index of 1.22 shows that the channels of the micro tend to be somewhat sinuous, which allows to infer that is permeable soil with good water infiltration. Based on the results of the morphometric variables was found that the watershed is in good condition of conservation, however, presents certain risks of susceptibility to erosion, and environmental degradation in some points, being fundamental to the maintenance of vegetation cover, in view of the roughness coefficient (Rn). Thus, the evaluation of morphometric characteristics in the study watershed constitutes an important tool in conjunction with the use of GIS and Geographic Information Systems makes possible the planning and management of natural resources aimed at their conservation.
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The objective of this study was to evaluate geoprocessing to morphometrically characterize the Ribeirão Descalvado micro watershed – Botucatu, SP by the Geographic Information System (GIS) – Selva for preservation, rationalization of its use and environmental restoration. The micro watershed is 2,228.61 ha between the geographic coordinates: 22° 50' 05" to 22° 54' 26" latitude S and 48° 22' 29" to 48° 26' 36" longitude W Gr. The cartographic basis was the planialtimetric chart of Botucatu (SP), 1: 50000 scale (IBGE, 1969), used for extraction of level, hydrography and topography curves to determine morphometric indices. The results showed that low values of drainage density associated with the presence of permeable rocks facilitates ground water infiltration which decreases surface runoff, erosion risks and environmental degradation. The low value of the shape factor supported by the circularity index shows that the micro watershed is more elongated and at lower risk of more pronounced floods. The roughness coefficient environmental parameter classified the micro watershed for forest and reforestation.
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
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The land use conservation planning requires knowledge of the soil characteristics, natural susceptibility to erosion and the soil loss limit. In this context, the objectives of this study were to perform a detailed soil survey of Ribeirão das Perobas watershed, located in Santa Cruz do Rio Pardo, São Paulo State and to determine and map the erodibility and soil loss tolerance of the soil classes found in the survey. The following techniques were used to perform the detailed soil survey: photopedology, field sampling, physical analysis, chemical analysis, and morphological description of the soil samples and profiles. The erodibility was determined by the methods described by Denardin (1990) and Mannigel et al. (2002), and the determination of soil loss tolerance followed the methodology of Mannigel et al. (2002). The results of erodibility determined by the methodology of Denardin (1990) were not discrepant and they did not distinguish soils that are known to have different susceptibility to erosion., w\Whereas, using the methodology of Mannigel et al. (2002), very high or very low erodibility values were observed in soils with extreme contents of sand silt or clay. The most influent variable to the soil loss tolerance results was the correction factor for the textural gradient of clay between soil horizons.
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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The study aimed mapping of the land use capacity classes for the Rio das Pedras watershed, Itatinga-SP in order to provide another mechanism of environmental planning for the studied area. It was used 1:10,000 topographic letters for the slope map generation which was overlaid with the studied area soil map. It was applied the judgment table criteria method, for generation of land use capacity map of the studied area. It were identified the following results: First, class III with constraints in relation of low fertility and restrictions about erosion risks on high slope areas. Second, class VI with the same characteristics of class III however with the presence of an aggravating factor of sand texture in all horizons, resulting in high risks of erosion events, especially in high slopes areas, and contamination by pollutants due the high soil permeability. Conclusions: It was verified that the more critical regions for land use capacity classes were VIs and mainly VIes class. The last one has more high relief areas and the presence of Neossolo Quartzarenico soil, with a big erosion propensity. The land use capacity map allow making different decisions for each region of the watershed respecting their individual characteristics.
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
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Pós-graduação em Geociências e Meio Ambiente - IGCE
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Pós-graduação em Geociências e Meio Ambiente - IGCE
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Pós-graduação em Geociências e Meio Ambiente - IGCE
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No garimpo do Manelão, o ouro está associado a veios de quartzo encaixados na seqüência metavulcano-sedimentar São Manoel. No período Plio-Pleistoceno, sob um clima úmido, desenvolveu-se sobre a seqüência São Manoel uma cobertura laterítica autóctone e imatura. Essa cobertura residual contém partículas de ouro com elevada pureza, sugerindo processos de lixiviação da liga Au-Ag ou de remobilização e redeposição do Au em ambiente laterítico. Durante o Pleistoceno, o clima tornou-se árido a semi-árido, favorecendo a erosão parcial da cobertura laterítica, através dos processos coluviais associados a enxurradas periódicas. Esse depósito coluvial recobre o perfíl laterítico, destruindo um possível padrão de dispersão geoquímica do ouro supergênico e prejudicando a prospecção geoquímica de superfície. No final do Pleistoceno e início do Holoceno, o clima úmido retorna, juntamente com os processos de intemperismo, formando stone line e latossolos. As coberturas laterítica e coluvial serviram de área-fonte para os aluviões atuais a subatuais do igarapé São Manoel, onde o ouro ocorre livre nos estratos sedimentares mais basais, formando concentrações da ordem de 10 g/ton.
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Pós-graduação em Geociências e Meio Ambiente - IGCE