998 resultados para Guadiana River


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Dissertação de mest., Gestão da Água e da Costa, Faculdade de Ciências e Tecnologia, Universidade do Algarve, 2009

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Dissertação de Mestrado, Biologia Marinha, Faculdade de Ciências do Mar e do Ambiente, Universidade do Algarve, 2007

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Strong water demand for irrigation, energy and drinking water production is responsible for an increasingly regulation of freshwater flow patterns and watersheds. In this context, the construction of dams allows water storage but seriously restricts freshwater flow downstream. Due to scarcity of freshwater resources, reservoir water management often promotes high hydraulic residence. This may cause strong impacts on biological components of aquatic ecosystems, influencing the development of cyanobacteria blooms and aggravating their harmful impacts.

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Tese de doutoramento, Ciências do Mar ( Processos de Ecossistemas Marinhos), Faculdade de Ciências e Tecnologia, Universidade do Algarve, 2012

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Following the Integrated Water Resources Management approach, the European Water Framework Directive demands Member States to develop water management plans at the catchment level. Those plans have to integrate the different interests and must be developed with stakeholder participation. To face these requirements, managers need tools to assess the impacts of possible management alternatives on natural and socio-economic systems. These tools should ideally be able to address the complexity and uncertainties of the water system, while serving as a platform for stakeholder participation. The objective of our research was to develop a participatory integrated assessment model, based on the combination of a crop model, an economic model and a participatory Bayesian network, with an application in the middle Guadiana sub-basin, in Spain. The methodology is intended to capture the complexity of water management problems, incorporating the relevant sectors, as well as the relevant scales involved in water management decision making. The integrated model has allowed us testing different management, market and climate change scenarios and assessing the impacts of such scenarios on the natural system (crops), on the socio-economic system (farms) and on the environment (water resources). Finally, this integrated assessment modelling process has allowed stakeholder participation, complying with the main requirements of current European water laws.

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A participatory modelling process has been conducted in two areas of the Guadiana river (the upper and the middle sub-basins), in Spain, with the aim of providing support for decision making in the water management field. The area has a semi-arid climate where irrigated agriculture plays a key role in the economic development of the region and accounts for around 90% of water use. Following the guidelines of the European Water Framework Directive, we promote stakeholder involvement in water management with the aim to achieve an improved understanding of the water system and to encourage the exchange of knowledge and views between stakeholders in order to help building a shared vision of the system. At the same time, the resulting models, which integrate the different sectors and views, provide some insight of the impacts that different management options and possible future scenarios could have. The methodology is based on a Bayesian network combined with an economic model and, in the middle Guadiana sub-basin, with a crop model. The resulting integrated modelling framework is used to simulate possible water policy, market and climate scenarios to find out the impacts of those scenarios on farm income and on the environment. At the end of the modelling process, an evaluation questionnaire was filled by participants in both sub-basins. Results show that this type of processes are found very helpful by stakeholders to improve the system understanding, to understand each others views and to reduce conflict when it exists. In addition, they found the model an extremely useful tool to support management. The graphical interface, the quantitative output and the explicit representation of uncertainty helped stakeholders to better understand the implications of the scenario tested. Finally, the combination of different types of models was also found very useful, as it allowed exploring in detail specific aspects of the water management problems.

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In this study we analyze the feeding ecology and trophic relationships of some of the main fish species (Soleidae, Moronidae, Mullidae, Sparidae, Mugilidae, and Batrachoididae) of the lower Estuary of the Guadiana River and the Castro Marim e Vila Real de Santo Antonio Salt Marsh. We examined the stomachs of 1415 fish caught monthly between September 2000 and August 2001. Feeding indices and coefficients were determined and used along with the results of multivariate analysis to develop diagrams of trophic interactions (food webs). Results show that these species are largely opportunistic predators. The most important prey items are amphipods, gobies (Gobiidae), shrimps (Palaemon serratus and Crangon crangon), and polychaete worms. The lower Estuary and associated salt marshes are important nurseries and feeding grounds for the species studied. In this area, it is therefore important to monitor the effects of changes in river runoff, nutrient input, and temperature that result from construction of the Alqueva Dam upstream. (c) 2006 Elsevier Ltd. All rights reserved.

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The feeding habits of two major species of sole, the common sole Solea vulgaris Quensel, 1806 and the Senegalese sole Solea senegalensis Kaup, 1858 were studied in the lower estuary of the Guadiana River (Algarve, southern Portugal). An evaluation of the number, weight, and feeding coefficient of prey types showed that S. vulgaris feed on a limited variety of prey (only Polychaeta and Tanaidacea) and present low-intensity feeding activity, with small differences in diet between seasons. S. senegalensis also have a low-diversity diet (with only one more taxa, Amphipoda), but exhibit more intense feeding activity which varies seasonally, although with little seasonal variation in the relative importance of the main preys. The diet composition of these two species suggests feeding specialization.

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Dissertação de Mestrado, Gestão da Água e da Costa, Faculdade de Ciências e Tecnologia, Universidade do Algarve, 2010

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Cyanobacteria are a recognised public health hazard, because the majority of species is able to produce toxins. The monitoring is usually restricted to freshwater environments, like lakes or dams used for water supply. Cyanobacteria blooms have been regularly reported in the Guadiana River and high estuary and most of the observed cyanobacteria were toxin producers.

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Resumo O trabalho de investigação que está a decorrer, tem como objeto de estudo as questões da identidade e da memória de uma aldeia alentejana, enquanto território de partilha de uma comunidade rural, tendo em conta a participação estratégica dos atores locais. Estudaremos a partir daí, a sua relação com a terra, o quotidiano, a mudança, a organização social, a ruralidade, os fatores portadores de futuro e novas propostas de desenvolvimento local, para territórios de baixa densidade. Pretende-se encontrar formas contributivas para preservar a identidade da aldeia e concomitantemente encontrar conjuntamente com os atores locais territorializados, alternativas de desenvolvimento local, capazes de contrariar a tendência de despovoamento e empobrecimento territorial. Com este trabalho de investigação, que se insere no âmbito da Sociologia da Ação, será utilizada metodologicamente o MACTOR e a sua aplicabilidade na determinação da estratégia de atores e respetivas relações de forças com o território e o que a ele diz respeito e ainda a observação participante/método de pesquisa de terreno e consequentemente o inquérito por entrevista. Pretendendo-se aprofundar e conhecer os problemas da interioridade e abandono populacional, designadamente na aldeia de Penedos que se situa na margem direita do rio Guadiana, freguesia de S. Miguel do Pinheiro e concelho de Mértola, no Baixo Alentejo. Abstract The research that is taking place, has as its object of study the issues of identity and memory of an Alentejo village, while sharing the territory of a rural community, taking into account the strategic participation of local actors. We'll look from there, his relationship with the earth, the everyday, change, social organization, rurality, the factors bearing on the future and new proposals for local development to areas of low density. The aim is to find ways contributory to preserve the identity of the village and found concomitantly in conjunction with local stakeholders territorialized, alternative local development, able to counteract the trend of depopulation and impoverishment territorial. With this research work, which falls within the Sociology of Action, will be used to methodologically MACTOR and its applicability in determining the strategy of respective actors and power relations with the territory and that he has concerns and participant observation / method of field research and thus the survey interview. Intending to go deeper and understand the problems of interiority and abandoned population, particularly in the village of Penedos which lies on the right bank of the Guadiana River, parish of S. Miguel do Pinheiro, county of Mértola, in the Baixo Alentejo.

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The human occupation of the Tavira ridge is characterised by a network of small agglomerations of buildings (known as ‘montes’) belonging to the proprietors of lands around them. This way of organising places is, by and large, extensive to an important area of the schist mountains that stretch from Alentejo to Algarve, from the Guadiana river to the Atlantic Ocean. However, within the scope of that larger entity, the Tavira ridge appears as a sub-unit with traits of its own, which may be attributed not only to biophysical conditions, but also to the historical circumstances associated to the settlement of the territory. This particular ridge, which was confined to the perimeter of the Tavira municipality during the days of the Old Regime, has been more densely populated, due to its lack of interior hierarchisation, unlike what happens in neighbouring sub-units, both in terms of agglomeration sizes and of the property system itself. The traditional architecture of these areas was usually reduced to the bare essentials, reflecting the adverse conditions that generally surrounded the local economies. As can easily be gleaned from the plans shown here, the groupings of edifices that define the ridge’s settlement are largely characterised by the aggregation of buildings belonging to various owners, often intent on achieving a prominent position in the landscape.

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Trabalho Final de Mestrado para obtenção do grau de Mestre em Engenharia Civil na Área de Especialização de Estruturas

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Sustaining irrigated agriculture to meet food production needs while maintaining aquatic ecosystems is at the heart of many policy debates in various parts of the world, especially in arid and semi-arid areas. Researchers and practitioners are increasingly calling for integrated approaches, and policy-makers are progressively supporting the inclusion of ecological and social aspects in water management programs. This paper contributes to this policy debate by providing an integrated economic-hydrologic modeling framework that captures the socio-economic and environmental effects of various policy initiatives and climate variability. This modeling integration includes a risk-based economic optimization model and a hydrologic water management simulation model that have been specified for the Middle Guadiana basin, a vulnerable drought-prone agro-ecological area with highly regulated river systems in southwest Spain. Namely, two key water policy interventions were investigated: the implementation of minimum environmental flows (supported by the European Water Framework Directive, EU WFD), and a reduction in the legal amount of water delivered for irrigation (planned measure included in the new Guadiana River Basin Management Plan, GRBMP, still under discussion). Results indicate that current patterns of excessive water use for irrigation in the basin may put environmental flow demands at risk, jeopardizing the WFD s goal of restoring the ?good ecological status? of water bodies by 2015. Conflicts between environmental and agricultural water uses will be stressed during prolonged dry episodes, and particularly in summer low-flow periods, when there is an important increase of crop irrigation water requirements. Securing minimum stream flows would entail a substantial reduction in irrigation water use for rice cultivation, which might affect the profitability and economic viability of small rice-growing farms located upstream in the river. The new GRBMP could contribute to balance competing water demands in the basin and to increase economic water productivity, but might not be sufficient to ensure the provision of environmental flows as required by the WFD. A thoroughly revision of the basin s water use concession system for irrigation seems to be needed in order to bring the GRBMP in line with the WFD objectives. Furthermore, the study illustrates that social, economic, institutional, and technological factors, in addition to bio-physical conditions, are important issues to be considered for designing and developing water management strategies. The research initiative presented in this paper demonstrates that hydro-economic models can explicitly integrate all these issues, constituting a valuable tool that could assist policy makers for implementing sustainable irrigation policies.

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An extension of guarantees related to rainfall-related risks in the insurance of processing tomato crops has been accompanied with a large increase in claims in Western Spain, suggesting that damages may have been underestimated in previous years. A database was built by linking agricultural insurance records, meteorological data from local weather stations, and topographic data. The risk of rainfall-related damages in processing tomato in the Extremenian Guadiana river basin (W Spain) was studied using a logistic model. Risks during the growth of the crop and at harvesting were modelled separately. First, the risk related to rainfall was modelled as a function of meteorological, terrain and management variables. The resulting models were used to identify the variables responsible for rainfall-related damages, with a view to assess the potential impact of extending insurance coverage, and to develop an index to express the suitability of the cropping system for insurance. The analyses reveal that damages at different stages of crop development correspond to different hazards. The geographic dependence of the risk influences the scale at which the model might have validity, which together with the year dependency, the possibility of implementing index based insurances is questioned.