United Nations Educational Scientific and Cultural Organization (UNESCO) Biosphere Reserves strive for a harmonious interaction between humans and nature. As landscapes provide suitable units to mutually address matters of conservation and sustainable development, this study aims to explore the potential and realized contribution of biosphere reserves for landscape governance and management. We emphasize the role of stakeholder participation and cooperation as an overarching condition for integrated landscape approaches. The regional focus is on Africa, where multiple drivers of global and local change currently significantly impact the landscape. The study’s results are based on a literature review, which is complemented by four case studies from the biosphere reserves in Ghana, Malawi, South Africa, and Benin/Togo. Findings show that in biosphere reserves, stakeholder engagement is crucial to gain community acceptance, foster intersectoral cooperation, and provide management with more legitimacy. To strengthen stakeholders’ capacities to mutually achieve conservation and development outcomes, international partnerships and research and education efforts proved to be successful. The flexible biosphere reserve approach to governance, which allows for integration with other land-management approaches, offers a suitable governance model for a landscape. Moreover, the biosphere reserve zonation concept can provide orientation to manage the “multifunctionality” of a landscape and address the associated trade-offs between different stakeholders’ aspirations.
Linear programming models are effective tools to support initial or periodic planning of agricultural enterprises, requiring, however, technical coefficients that can be determined using computer simulation models. This paper, presented in two parts, deals with the development, application and tests of a methodology and of a computational modeling tool to support planning of irrigated agriculture activities. Part I aimed at the development and application, including sensitivity analysis, of a multiyear linear programming model to optimize the financial return and water use, at farm level for Jaíba irrigation scheme, Minas Gerais State, Brazil, using data on crop irrigation requirement and yield, obtained from previous simulation with MCID model. The linear programming model outputted a crop pattern to which a maximum total net present value of R$ 372,723.00 for the four years period, was obtained. Constraints on monthly water availability, labor, land and production were critical in the optimal solution. In relation to the water use optimization, it was verified that an expressive reductions on the irrigation requirements may be achieved by small reductions on the maximum total net present value.KEYWORDS: irrigation requirement, financial return, simulation model. MODELAGEM COMPUTACIONAL PARA PLANEJAMENTO EM AGRICULTURA IRRIGADA. PARTE I: DESCRIÇÃO GERAL E PROGRAMAÇÃO LINEAR 1RESUMO: Modelos de programação linear são ferramentas eficazes de suporte ao planejamento inicial ou periódico de empreendimentos agrícolas, requerendo, todavia, coeficientes técnicos que podem ser obtidos por modelos computacionais de simulação. Este trabalho, dividido em duas partes, aborda o desenvolvimento, a aplicação e os testes de metodologia e da modelagem computacional de uma ferramenta de auxílio ao planejamento da exploração agrícola irrigada. Teve-se o objetivo de desenvolver e aplicar, com análise de sensibilidade, um modelo de programação linear plurianual para otimização do retorno financeiro e uso da água, em nível de propriedade rural no perímetro de irrigação do Jaíba -MG, utilizando dados de requerimento de irrigação e produtividade de culturas, obtidos com o modelo de simulação MCID. O modelo de programação linear indicou um padrão de cultivo para o qual se obteve o máximo valor presente líquido total, de R$ 372.723,00 para o período de quatro anos. Restrições quanto à disponibilidade mensal de água, mão-de-obra, terra e produção foram críticas na solução ótima. Em relação à otimização de uso da água, verificou-se que expressivas reduções no requerimento de irrigação podem ser obtidas com pequenas reduções no valor presente líquido total máximo.
This paper addresses the question as to whether it is profitable to apply a mechanical mulching technology (MT) in the Bragantina region of Brazil and assesses the technology's feasibility as an alternative to the slash-and-burn practices of the Amazon. Using empirical data collected from a prototype assessment and a few secondary sources, the paper employs a cost-benefit analysis of 'with' and 'without' technology cropping systems (plots that applied the technology are compared with those that did not) to assess the financial and economic feasibility of investing in the MT. The analysis showed that the technology is profitable, both financially and socially, mainly because it is able to produce yields that are high enough to offset the costs, including the hiring of the mulching equipment. However, it may not be a feasible alternative to slash-and-burn farming unless certain conditions are fulfilled by farmers. Most of these conditions relate to farmers' adherence to a set of rules for the successful application of the technology. These rules include the abandonment of a single cropping cycle, typical for the traditional slash-and-burn system, and the adoption of two cycles of crop cultivation. In addition, farmers have to choose profitable crop combinations, such as cassava and beans for both cycles. Since most of the trial farmers did not meet these conditions, the technology received a notably low acceptability (8%). Further analysis indicated that the main reason for this trend was the increase of total labor requirement (by 32%), though the technology reduced labor demand during land preparation to almost zero. Similarly, there was a 22% increase in requirement for inorganic fertilizers. Thus, compared with the slash-and-burn practices of the Amazon, the MT can be regarded as a more intensive method of farming which gives higher crop yields but demands higher quantities of inputs such as labor and inorganic fertilizers. The paper concludes by deriving policy implications for the feasibility of the MT as an alternative to slash-and-burn agriculture in the Amazon. Among these is the importance of creating incentives to extend the cropping period from one to two consecutive cycles. Moreover, the necessity to conduct further studies after the technology has been adopted by the farmers is underscored.
RESUMOEste trabalho se refere ao desenvolvimento de um modelo computacional para suporte à tomada de decisão, quanto ao planejamento e manejo de projetos de irrigação e/ou drenagem. O modelo computacional, denominado MCID, é aplicá-vel em nível de unidade de produção, gerando informações sobre como diferentes práticas de manejo da irrigação e configurações do sistema de drenagem afetam a produtividade e o retorno financeiro. Essas informações podem ser empregadas em estudos de otimização de padrão de cultivo em nível de propriedade agrícola, em relação ao retorno financeiro e ao uso da água, associados à análise de risco com base em simulações. O balanço hídrico e de sais na zona radicular e as estimativas da profundidade do lençol freático e vazão nos drenos, são conduzidos em base diária. A análise de sensibilidade indicou que os parâmetros de entrada que mais influenciaram o requerimento de irrigação totalizado para o ciclo, foram espaçamento entre drenos, porosidade drenável, número da curva, condutividade hidráulica horizontal do solo saturado, profundidade da camada impermeável e os parâmetros n e α do modelo de van GenuchtenMualem. Palavras-chave: irrigação, drenagem, manejo solo-água-planta-salinidade, análise financeiraComputer model for decision support on irrigated areas Part I: Development and sensitivity analysis ABSTRACT This paper refers to the development of a decision support model for planning and managing irrigation and/or drainage schemes. The computer model, called MCID, is applicable to a production unit level, generating information on how different irrigation management practices and drainage designs affect crop yield and financial return. This information may be applied in studies of crop patterns at farm level, taking into consideration financial return and water use, associated to risk analysis based on simulations. The water and salt balance in the root zone, as well as the water table depth and drain discharge predictions, are carried out on a daily basis. The sensitivity analysis pointed out that the most influential parameters on the seasonal irrigation requirement were: drain spacings, drainable porosity, curve number, horizontal soil saturated hydraulic conductivity, impermeable layer depth and the van Genuchten-Mualem parameters n and α.
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