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- The water crisis in southern Portugal: how did we get there and how should we solve itPublication . Nunes, Luís; Monteiro, José Paulo; Cunha, Maria da Conceição; Vieira, João; Lucas, Helena; Ribeiro, LuísUntil very recently, public water supply in the Algarve region was almost entirely supported by groundwater wells. However, in the last years of the XX Century, the Portuguese central administration defined a scheme for the public water supply sector entirely based in surface water from large dams, in order to guarantee the public water supply. The efforts to abandon groundwater as a source for public supply started in 1998, after a large investment in new infrastructures and rehabilitation of other ones. However, the practical implementation of this water supply scheme showed that an integrated resource management is needed in order to implement a more economical and reliable solution. The present paper describes the historical background and the evolution of water use in the last decades until the present time in the Algarve, and a proposal for restructuring the management of the water supplies based in the development of a decision support system in the scope of an integrated water resources management.
- OPTEXPLOR – new application for water resources management for private water supply utilitiesPublication . Nunes, L.; Monteiro, José Paulo; Stigter, T. Y.; Ribau Teixeira, Margarida; Nascimento, João; Ribeiro, L.; Lucas, HelenaThis article presents the steps made for the development of a new water management system (WMS) for a private water utility in the south of Portugal, and its main results. The WMS is composed of a set of models representing the water resources, surface and groundwater, water quality models, economic models, and water allocation optimization models. The system was developed at the request of the regional water utility (Águas do Algarve, S.A.), which is responsible for distributing water to the entire Algarve region (most touristic area in Portugal, with about ten million tourists per year, and a local population of about four hundred thousand). Results clearly show that independently of the amount of water available, inter-annual exploration is always the best solution, if possible. When water scarcity is high, as in consecutive dry years, the water utility will need to call municipalities to use their systems to complement supply. The level of supply deficit is higher, in any case, for annual exploration management, and so are exploration costs. These results clearly show that water resources management needs careful inter-annual planning, even for a private water supply utility with very limited control over water exploration by other competing users.
- Screening of sustainable groundwater sources for integration into a regional drought-prone water supply systemPublication . Stigter, T. Y.; Monteiro, José Paulo; Nunes, L.; Vieira, João; Cunha, Maria da Conceição; Ribeiro, Luís; Nascimento, João; Lucas, HelenaThis paper reports on the qualitative and quantitative screening of groundwater sources for integration into the public water supply system of the Algarve, Portugal. The results are employed in a decision support system currently under development for an integrated water resources management scheme in the region. Such a scheme is crucial for several reasons, including the extreme seasonal and annual variations in rainfall, the effect of climate change on more frequent and long-lasting droughts, the continuously increasing water demand and the high risk of a single-source water supply policy. The latter was revealed during the severe drought of 2004 and 2005, when surface reservoirs were depleted and the regional water demand could not be met, despite the drilling of emergency wells. For screening and selection, quantitative criteria are based on aquifer properties and well yields, whereas qualitative criteria are defined by water quality indices. These reflect the well’s degree of violation of drinking water standards for different sets of variables, including toxicity parameters, nitrate and chloride, iron and manganese and microbiological parameters. Results indicate the current availability of at least 1100 l s−1 of high quality groundwater (55% of the regional demand), requiring only disinfection (900 l s−1) or basic treatment, prior to human consumption. These groundwater withdrawals are sustainable when compared to mean annual recharge, considering that at least 40% is preserved for ecological demands. A more accurate and comprehensive analysis of sustainability is performed with the help of steady-state and transient groundwater flow simulations, which account for aquifer geometry, boundary conditions, recharge and discharge rates, pumping activity and season. (tibor.stigter@ist.utl.pt) ality. They permit an advanced analysis of present and future scenarios and show that increasing water demands and decreasing rainfall will make the water supply system extremely vulnerable, with a high risk of groundwater salinization and ecosystem degradation.