Alexandre Marco da Silva

Environmental fragility evaluation and guidelines for environmental zoning: a study case on Ibiuna (the Southeastern Brazilian region)

Environmental fragility models are important decision tools for policy makers as they help quantify environmental sensitivity and understand the relationship between human activities and environmental quality. The objective of this study was to evaluate three different environmental fragility models within the Brazilian rainforest region and to use the results to develop environmental zone classes. Two rural river basins located in Ibiuna, Sao Paulo state, Brazil, were studied. Input variables, including slope class, relief dissection rate, soil class, lithology, land cover, and climate data, were used to compute environmental fragility classes using three standard models. The model outputs were evaluated on their ability to accurately predict the most sensitive and least sensitive areas. The best models for each region were used to derive environmental zoning maps, including restoration priorities, best regions for agriculture, and areas with high needs for soil management. These maps will help support land use strategies for environmental restoration. This study provides insight into territorial ordering and management of environmental services with a regional perspective.

Natural Potential for Erosion for Brazilian Territory

Erosion and sedimentation refer to the motion of solid particles, called sediment (Julien, 2010). Erosion is a natural process and causes a breakdown of soil aggregates and accelerates the removal of organic and mineral materials (Gilley, 2005). Soil erosion risk can be assessed by means of equations empirically derived from the superposition principle of this phenomenon. Using such models, during the last decade, several initiatives have assessed the risk of soil erosion at the national, continental, and global levels (Terranova et al., 2009). The use of geographic information system (GIS) enables the determination of the spatial distribution of the parameters of some soil loss predicting models, as the Universal Soil Loss Equation USLE (Dabral et al., 2008). Every factor within the USLE is calculated by GIS, which is obtained from meteorological stations, topographic maps, land use maps, soil maps and results of other relevant studies. The spatial distribution of the soil loss of a certain region is given by multiplying factor map layers in the GIS. The spatial resolution of the data is an option of researcher, and should be considered the resolution of the Digital Elevation Model (DEM), soil map, satellite images, among other sources of information (Yue-Qing et al., 2008). Land use is the only factor affecting erosion that can be modified to reduce soil loss potential (Gilley, 2005). However, if we do not consider the land cover and soil management, i.e., if we consider the interaction of rainfall, topography and soil, assuming that the soil is totally uncovered along wholly study area, we may predict the total soil loss amount or the Natural Potential for Erosion (NPE) for a considered area (Castro & Valerio Filho, 1997). NPE might be used as a tool to show cartographically areas highly pre-disposed to erosion and the mathematic relation among PNE value and soil loss tolerance value. It might indicate the ideal CP factor to be used in determined region. Brazil is largest South American country and the land use is far from to be conformable with land use capability. Hence, soil loss studies and researches are highly needed. On the other hand, a lot of studies have been developed in order to predict soil loss rates along Brazilian

Teores e quantidades de alguns elementos no córrego Lavapés, subbacia do rio Sorocaba, São Paulo, Brasil

Este trabalho teve por objetivo verificar a condicao ionica sazonal de um corrego de ocupacao predominantemente urbana localizado na cidade de Sorocaba/SP, assim como verificar as taxas de exportacao de nutrientes dessa microbacia e impactos no rio Sorocaba localizado na mesma cidade. Para o estudo foram realizadas coletas de agua durante 12 meses, em dois pontos de coleta, entre os anos de 2009 e 2010. As analises dos atributos quimicos foram realizadas em laboratorio mediante metodologias de titulometria e espectrofotometria. Os atributos verificados foram magnesio, calcio, alcalinidade, sulfato, cloreto, potassio, nitrato e fosforo total. Os resultados foram apresentados em forma de Diagramas de Maucha para os 12 meses, enquanto os atributos nitrato e fosforo total foram utilizados para calculo de taxas de exportacao de nutrientes. Nao foram observadas grandes discrepâncias sazonais pelos diagramas apresentados, em relacao a proporcionalidade. A dominância geral de cations foi a seguinte para os dois pontos: Ca2+ > Mg2+ > K+. Enquanto a ordem de dominância dos ânions foi: Alcalinidade > SO42- > Cl-. As taxas de exportacao da regiao foram maiores nos periodos chuvosos. A microbacia tem baixa influencia no montante estimado para a bacia do rio Sorocaba, cerca de 5,83 toneladas de Nitrato e 0,14 toneladas de Fosforo total de um total estimado de 1706 t e 426 t respectivamente. Segundo a classificacao do indice de estado trofico o corrego Lavapes e considerado como mesotrofico.