José Fernando Rodrigues Bezerra

Slope Processes, Mass Movement and Soil Erosion: A Review

Abstract Soil erosion and land degradation are global problems and pose major issues in many countries. Both soil erosion and mass movement are two forms of land degradation and humans play important roles in these geomorphological processes. This paper reviews slope processes associated with mass movement and soil erosion and contributory factors, including physical and human agents. Acting together, these cause diverse geomorphological features. Slope processes are illustrated by reference to case studies from Brazil and UK. The causes and impacts of erosion are discussed, along with appropriate remedial bioengineering methods and the potential of the measures to prevent these types of environmental degradation. Although there are several agents of erosion, water is the most important one. Cultivation can promote soil erosion, due to ploughing and harvesting, which moves soil down slopes. Soil erosion and mass movement data would inform the viability of soil conservation practices. Integrated management of drainage basins offers a promising way forward for effective soil conservation and soil remedial bioengineering in Brazil and UK.

Land rehabilitation with the use of biological geotextiles, in two different countries

This paper assesses the role of biological geotextiles on non-agricultural erosion environments, based on studies in the mine tailings Gauteng Province (South Africa) and urban area of Sao Luis City (Brazil). Gauteng Province (South Africa) has suffered immense problems related to sustainable rehabilitation of mine dumps. This is a huge challenge, as wastes are highly susceptible to both water and wind erosion. Establishing a grass cover to reduce erosion is the dominant reclamation method. Covering the slopes with biological geotextiles might constitute another option for mining companies to reduce erosion and aid natural re-vegetation. The objective of the waste part of this study was to determine the beneficial effect of palm mat cover on erosion control, using rainfall simulation. Results clearly illustrated that application of palm-mats more than halved the sediment load in runoff, thereby having the potential to effectively stabilize tailing dam slopes. Covering tailings with palm-mats did not reduce runoff or improve water infiltration, however. In Sao Luis City, biological geotextile mats were constructed from palm leaves which are an effective, sustainable and economically-viable soil conservation technique. At Sacavem Community biological geotextile mats were used in association with barriers of wooden stakes and the construction of terraces along contour lines. The aim is to minimize soil erosion, by intercepting rainfall, retarding runoff velocity and sediment loss.

RELAÇOES ENTRE POTENCIAL MATRICIAL NO SOLO E COBERTURA VEGETAL EM UMA ESTAÇÃO EXPERIMENTAL, UBERLÂNDIA - MG

Faz-se neste artigo uma analise sobre a relacao entre o potencial matricial e a cobertura vegetal em uma estacao experimental na Fazenda do Gloria, Uberlândia- MG, com base nos dados obtidos nos tensiometros e na fotocomparacao. Foram adotados os seguintes procedimentos: a. Construcao de duas parcelas de 10 m2 cada, uma com Solo Exposto (SE) e outra com Geotexteis e Gramineas (SG); b. A analise granulometrica dos sedimentos foi baseada na proposta da EMBRAPA; c. Monitoramento de duas baterias de tensiometros nas parcelas com solo exposto e com geotexteis em diferentes profundidades (15, 30, 80 e 120 cm), com o auxilio de um tensimetro digital INFIELD 5; e d. Fotocomparacao com classificacao supervisionada usando software de sensoriamento remoto. Os resultados foram divididos em tres fases: 1. na fase 1, a ocupacao da cobertura vegetal variou entre 0 a 6,4%, destacando-se o tensiometro de 120 cm cm na parcela com geotexteis, que atingiu -20 kPa; 2. na fase 2, com uma taxa de ocupacao variando entre 15,2% a 59,4 % na parcela com geotexteis e gramineas, o potencial matricial chegou a -32,4 kPa na profundidade de 15 cm; e 3. na fase 3, com uma taxa de ocupacao da graminea entre 63,9% a 100% , cita-se o tensiometro de 30 cm, que chegou a -67 kPa.

Uso do mercúrio e reflexos socioambientais no garimpo de caxias, município de Luís Domingues– MA

A atividade de mineracao e imprescindivel para o desenvolvimento das sociedades e da economia em seus mais diversos setores produtivos, sendo, ao longo dos anos, um dos sustentaculos economico e politico. Porem, os impactos causados pela mineracao, vem onerando o ambiente drasticamente, sobretudo o uso de produtos, como o mercurio. Neste sentido, a pesquisa analisa os problemas ambientais e sociais provenientes da extracao mineral sobretudo ao uso do mercurio no Garimpo de Caxias, localizado no Municipio de Luis Domingues- MA, porcao noroeste do Estado do Maranhao. A pesquisa propos metodologia baseada no Geossistema, afim de diagnosticar as consequencias dessa atividade nos meios fisico, biotico e antropico. Diante dos estudos, concluiu-se que os moldes de producao investigados, proporciona pouquissimo aspectos positivos (atividade fim de sobrevivencia do garimpeiro, remuneracao), tem fomentado impactos socioambientais negativos, os quais constituem para um cenario instavel ameacando o bem estar social e equilibrio do ambiente local.

Gully Erosion and Land Degradation in Brazil: A Case Study from São Luís Municipality, Maranhão State

Soil erosion and land degradation are global problems and pose major problems in Brazil, which is characterized by a great diversity of soil types. This chapter discusses gully erosion and land degradation in Brazil, outlining a case study from Sao Luis City, Maranhao State. This diversity is related to a wide variety of landforms, climates, parent materials, vegetation cover and biota and is influenced by land use and management. Therefore, a brief description of different types of land degradation, mainly gully erosion and mass movements, is presented, and illustrative photographs are presented. These hazards affect both urban and rural areas within the extensive national territory (8,547,403 km2). Consequently, these problems have serious environmental impacts and pose socio-economic challenges.