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Accueil du site → Doctorat → Australie → 2014 → Recharge to a semi-arid, heterogeneous coastal aquifer : Uley South Basin, South Australia

Flinders University of South Australia (2014)

Recharge to a semi-arid, heterogeneous coastal aquifer : Uley South Basin, South Australia

Miraldo Ordens Carlos Miguel

Titre : Recharge to a semi-arid, heterogeneous coastal aquifer : Uley South Basin, South Australia

Auteur : Miraldo Ordens Carlos Miguel

Université de soutenance : Flinders University of South Australia

Grade : Doctor of Philosophy (PhD) 2014

Résumé partiel
Groundwater is a resource of increasing importance throughout the world, especially in arid and semi-arid regions. Prudent groundwater management is paramount for the sustainability of groundwater systems, both in terms of water quantity and quality. Reliable estimates of groundwater recharge are often a pre-requisite for such purposes, as well as for most groundwater studies. However, groundwater recharge is commonly poorly understood and recharge estimates are usually highly uncertain due to its complicated nature and the lack of data. Distributed groundwater recharge (simply termed ’recharge’ in what follows) is the vertical downward movement of water through the unsaturated zone, reaching the water table, and going into storage. Recharge can occur through focused and/or diffuse mechanisms. In any assessment of recharge, these mechanisms and other important factors are described by a conceptual model, which serves as the starting point of any recharge characterisation, and is necessary for appropriate selection of recharge estimation methods. Despite the significance of a sound conceptual model of recharge processes, it is often untested in recharge evaluations. This study explores the recharge processes within the coastal, semi-arid Uley South Basin (USB), Eyre Peninsula, South Australia, and attempts to quantify the spatial and temporal variability in recharge fluxes to the system. This aquifer presents significant management challenges, because it supplies around 70% of the Eyre Peninsula’s water demand, and yet there have been historical declines in groundwater levels approaching mean sea level in places. At the time of this study, USB was managed entirely based on recharge estimates, and reliable recharge estimates remain central to the sustainable allocation of pumping from the basin. A predictive tool capable of simulating recharge across the basin is required, partly for direct management applications, but also to underpin proposed groundwater models of USB. The carbonate terrain of USB forms a recharge environment that is especially challenging to characterise, and previous studies that have attempted to quantify USB recharge produced a wide range of basin- and time-averaged estimates (i.e. 40 to 200 mm/year). There is a need to seek plausible explanations for the lack of agreement across these studies, particularly because management requires a narrow range of uncertainty in USB recharge. Consequently, the focus of this study is to develop an improved characterisation of USB recharge, and to critically examine field-based and modelling approaches as they apply to the USB conditions.

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