Regions with high hydrological variability are usually supplied by reservoirs that regularize discharges inter-annually, with low discharge of regularization, seasonally subject to large overflow and evaporation losses in their periods of high water levels. The Brazilian semiarid is one of such regions. This work looks at the possibility of using water that would be evaporated and/or spilled, in regions with such characteristics, to supply demands that would not be otherwise provided by the maximum legally allowed withdrawal discharge. The proposed method was applied to the operation of a large reservoir, located in the semiarid region of Brazil. Through simulation of the water budget and optimization, a rule curve was developed for reservoir operation for achieving the maximum exploitable reservoir withdrawal in rainy periods. The results show that it is possible to use the excess water in periods of large inflows with no damage to water supply during dry periods.Keywords: Concession discharge; Reservoir operation; Rule curve. RESUMORegiões com alta variabilidade hidrológica são, geralmente, abastecidas por reservatórios plurianuais com baixas vazões de regularização, sujeitos, sazonalmente, a grandes vertimentos e a perdas por evaporação em seus períodos de cotas altas. O semiárido brasileiro é uma dessas regiões. Este trabalho levanta a hipótese do aproveitamento da água vertida e/ou evaporada, em regiões com estas características, para suprir demandas não atendidas pela vazão outorgável dos reservatórios, utilizando uma vazão máxima excedente para incrementar a vazão outorgável. Como caso de estudo, foi efetuada a operação de um reservatório de grande porte, localizado no semiárido brasileiro. Por meio de simulação do balanço hídrico e otimização, foi desenvolvida uma curva-guia para operação do reservatório e encontrada a vazão excedente máxima explorável em períodos de cheia. Com os resultados encontrados, pode-se concluir que há a possibilidade de utilizar uma vazão excedente em períodos de grandes afluências sem que o abastecimento em períodos secos seja prejudicado.Palavras-chave: Vazão outorgável; Operação de reservatórios; Curva-guia.
Small and shallow alluvial aquifers in arid and semi-arid regions compose an important water system that smallholder farmers rely on for irrigation and livestock feeding. Geological settings and the small scale of these aquifers suggest the need for governance at the local level, but research supporting its development is still scarce.Treating a case of alluvial aquifers exploited by smallholder farmers located in the Brazilian semi-arid region as a common pool resource (CPR), this paper analyses the governance of a social-ecological system (SES) for which an alluvial aquifer is an essential source of water. The paper applies the SES Framework to analyse the SES in light of Ostrom's principles for sustainable CPR management to answer the questions: (a) can the governance arrangements support sustainable common pool resource management of the alluvial aquifers? (b) what opportunities are there to make the management of the aquifer more sustainable through community-based governance? (c) can Ostrom's design principles lead the transition to more sustainable governance of alluvial aquifers? Despite a water policy aiming for decentralisation and participatory governance, gaps in the implementation of these policies are identified. Taking into account the challenges imposed by the aquifer characteristics to impact efficient groundwater exploitation, equity in water distribution and conservation of the CPR, the analysis reveals opportunities to improve CPR management by supporting the community to increase participation in the governance of the aquifer in coordination with existing policies. This work concludes with suggestions that could empower community progress towards more sustainable governance of the aquifer.
A crescente exploração das águas subterrâneas, devido, principalmente, aos baixos custos e boa qualidade tem exigido a necessidade de regulação de suas disponibilidades, tanto em quantidade quanto em qualidade. Um dos instrumentos instituídos pela Lei Federal nº. 9.433/97 para efetivar este controle é a outorga de direito de uso das águas, mediante a verificação de critérios pré-estabelecidos. Todavia, verifica-se que não há critérios consolidados para determinação da outorga das águas subterrâneas. Sendo assim, neste artigo são propostos critérios da outorga de direito de uso aplicados às águas subterrâneas, compatíveis com as suas condições de armazenamento e escoamento e com suas relações com o ciclo hidrológico, particularmente com as águas fluviais. Como caso de estudo foi utilizada a parcela da Bacia Sedimentar Costeira Paraíba-Pernambuco inserida na Região do Baixo Curso do rio Paraíba, estado da Paraíba, Brasil. Através da construção de um modelo conceitual dos processos hidrogeológicos da região em estudo, estabeleceram-se critérios de outorga de acordo com a realidade da bacia. Como resultados, foram propostos níveis de abrangência destes critérios, assim definidos: níveis global, regional e local. A criação do nível de abrangência regional demandou que fossem identificadas sete "zonas de gerenciamento", nas quais poderão ser estabelecidos critérios diferenciados de uma zona para outra.Palavras-chave: gestão de recursos hídricos, critérios de outorga, Bacia do rio Paraíba.
Easily exploitable aquifers are formed along river beds in the Brazilian semi-arid region and present characteristics that enable the construction of underground dams. The estimate of the potential effective exploitation of these aquifers must take into account the pumping limits of the wells, the upstream groundwater inflows and the flows to downstream reaches and through the underground dam, whose reduction influences the downstream supply. The current research presents a real case study about an aquifer reach, with underground dam and wells, which was analyzed through computational model. We simulated the groundwater flow patterns according to different exploitation scenarios and found that there should be water extraction limitations to assure the required downstream flows. The limitations can be minimized through appropriate well locations and exploitation regimes, as well as through the implementation of underground dams. The definition of these measures becomes possible through the sound use of computational simulation, but their effective implementation will depend on negotiations among users at the basin scale, so that appropriate water permits can be issued.
Urban planning requires the integration of several disciplines, among them ones related to water resources. The impacts of urban development on those resources, and viceversa, are well known, but some aspects have not been well characterized in literature. This research analyzes a case that shows interesting relationships between urban planning, its legislation, the evolution of urban occupation and several aspects of water resources: groundwater, surface water, drainage and saltwater intrusion. The research argues for integrated and dynamic planning, monitoring and directive enforcement of the urban processes, including environmental dimension and water resources. Advanced decision support techniques are suggested as tools for supporting this integrated approach.
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