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Universidade do Porto (2011)

Avaliação e gestão de situações de seca e escassez : Aplicação ao caso do Guadiana

Bruno de Freitas Vivas, Eduardo

Titre : Avaliação e gestão de situações de seca e escassez : Aplicação ao caso do Guadiana

Auteur : Bruno de Freitas Vivas, Eduardo

Université de soutenance : Universidade do Porto

Grade : Tese de Doutoramento. Engenharia Civil 2011

Résumé
Droughts and water scarcity are different and complex problems, with significant impacts. Commonly, these are coexistent and interdependent in the same region. Drought, as natural phenomenon, cannot be avoided, while water scarcity is a result of human action and is directly associated to regional development. Nonetheless, water scarcity enhances regional vulnerability to potential precipitation deficits.
At current state, there are already several methods for droughts’ monitoring and evaluation and, also, some procedures for water scarcity estimation. Although these assessments are based in the evaluation of specific indicators/ indices, both for droughts or water scarcity, none of the existent methodologies can be universally applied or take into account the regional specificities for impacts’ prediction. In the case of droughts, the impacts are mostly dependent of the existent water uses, types of water sources, and even the regional socioeconomic characteristics, reason why the evaluation of precipitation values is not sufficient. Water scarcity quantification, though, depends on the variation of water sources availability, water uses and, also, on the existing infrastructures, being difficult to define an accurate evaluation criterion.
The main goal of this thesis is, then, the definition of a methodology for droughts’ evaluation and management, adapted to Portuguese reality. It is also envisaged that this evaluation reflects the potential socioeconomic impacts of a drought situation, supporting decision making on preventive and operational management of drought situations. Moreover, the methodology shall be able to take water scarcity problems into account.
Considering the Guadiana’s river basin, the selected case study was the Portuguese area upstream Alqueva’s dam. The more important characteristics of this area are the regular occurrence of droughts, the dependence on Spanish water inflows and the representativity of the present and future management of regional water resources, regarding the strategic Alqueva’s water reservoir and the foreseen development of intensive agriculture.
The methodology developed in the thesis is based on the evaluation of different variables, representative of the different hydrological stages and, consequently, of the main water sources of the region. The assessment of potential drought effects is assured with numerical modeling of water sources’ availability, under probable meteorological scenarios. The estimation of regional economic impacts due to drought is assured, for main water users, regarding the income reduction on agricultural sector and the increase of water supply costs, in urban sector, to satisfy demand. The application of the same procedure to long term simulations (10 years) will enable, also, the overall analysis of water sources and identification of scarcity problems.
From the attained results it is possible to conclude the reasonable evaluation and impacts’ estimation of drought situations occurred in the period of assessment 1998/99 to 2008/2009, as well as the prediction of drought impacts for 2004/05. Moreover, is possible to confirm the identification of specific situations of water use restrictions (water scarcity), and attain the estimation of respective socioeconomic impacts.

Mots clés  : características da região, monitorização, modelação, balanço disponibilidades/ necessidades, avaliação económica. — regional characteristics, monitoring, modeling, availabilities/ water use balance, economic assessment.

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Page publiée le 11 décembre 2016, mise à jour le 12 juin 2017