Geotecno (Brazil)

As rupturas recentes de barragens de rejeitos no Brasil têm causado graves impactos ambientais, mortes e perdas financeiras. Este artigo apresenta uma breve descrição da evolução das atividades de mineração no Brasil e dos principais acidentes ocorridos nas últimas 4 décadas. As falhas são apontadas, com o intuito de sugerir os itens que demandam a atenção de técnicos, empresários e governantes. Alterações da gestão e operação dos rejeitos são necessárias para uma melhoria das condições de segurança das barragens de mineração.

Changes in land cover have a direct impact on forest ecosystem goods and services. In this study, changes in land cover in Sierra de Juarez–Oaxaca ecosystems were estimated using a consistent processing of Landsat images and OBIA methodology. Additionally, landscape analyses using FRAGSTAT were conducted. In 2014, Sierra de Juarez–Oaxaca was covered by approximately 84% of forests, mainly pine-oak and cloud forests. After extensive deforestation until 2001, this trend was reversed and the forest cover surface area in 2014 was slightly higher than in 1979. The comparison of the landscape structure of the forested and agricultural lands suggests an increase in habitat heterogeneity. However, interspersion and juxtaposition indices, showing the patch shape by patch area and perimeter, were similar throughout the study period (1979–2014). Social and economic drivers can explain this situation: namely, community organization, forest enterprises, payment for ecosystem services programs, and changes of agricultural activity. Communities in the Sierra of Oaxaca have reforested degraded lands, created community forest enterprises, and preserved the forest under conservation schemes like those proposed by the Mexican payment for ecosystem services programs. However, their sustainable management faces internal challenges and has become highly dependent on political and institutional decisions beyond their control.

This work presents and analyses a geostatistical methodology for spatial modelling of Soil Lime Requirements (SLR) considering punctual samples of Cation Exchange Capacity (CEC) and Base Saturation (BS) soil properties. Geostatistical Sequential Indicator Simulation is used to draw realizations from the joint uncertainty distributions of the CEC and the BS input variables. The joint distributions are accomplished applying the Principal Component Analyses (PCA) approach. The Monte Carlo method for handling error propagations is used to obtain realization values of the SLR model which are considered to compute and store statistics from the output uncertainty model. From these statistics, it is obtained predictions and uncertainty maps that represent the spatial variation of the output variable and the propagated uncertainty respectively. Therefore, the prediction map of the output model is qualified with uncertainty information that should be used on decision making activities related to the planning and management of environmental phenomena. The proposed methodology for SLR modelling presented in this article is illustrated using CEC and BS input sample sets obtained in a farm located in Ponta Grossa city, Parana state, Brazil.

Este trabalho tem como objetivo a utilizacao do Google Earth para a producao de materiais didaticos voltados para o ensino de Geografia, sobretudo de temas de Geomorfologia e espaco geografico, para estudantes do ensino fundamental 2, que vivem na Ilha do Governador, municipio do Rio de Janeiro. O uso de imagens extraidas do Google Earth, em diferentes escalas, permite aos alunos uma interpretacao mais completa de suas vizinhancas, alem de possibilitar a integracao espacial de diferentes componentes espaciais com a Baia de Guanabara. E interessante notar que a utilizacao desta ferramenta facilita a visualizacao obliqua e vertical do espaco, e ainda em perspectiva 2D e 3D, bem como a abordagem de temas geograficos de uma forma dinâmica e interdisciplinar. A escolha dos temas foi baseada no estudo dos Parâmetros Curriculares Nacionais (PCN), e tambem sobre os conteudos considerados importantes para os alunos das escolas de Ilha do Governador. As atividades foram construidas em folhas A4 a um baixo custo, e aplicadas para introduzir os temas a serem discutidos nas aulas de geografia, tornando possivel ainda a revisao do conhecimento previo dos alunos, alem de contribuir no desenvolvimento de habilidades voltadas para analise de dados espaciais.