Suchergebnisse

Appropriate characterisation, modelling and management of coastal aquifers requires knowledge of the dynamic balance between freshwater and saltwater present in the aquifer as a result of natural marine intrusion or other salinisation processes of geological or anthropogenic origin. Monitoring this balance is essential for the timely detection and prediction of groundwater deterioration and the sustainable management of abstraction schemes. Recent advances in hydrogeophysical methods allow more accurate non-invasive assessments of intrusion dynamics and evolution, thus providing vital input to the generation and refinement of conceptual and numerical hydraulic models of coastal aquifers. The purpose of this study of the Lower Andarax delta in the Andalucía region of southeast Spain is to combine time-lapse electrical resistivity tomography (ERT) with conventional intrusive methods (borehole sampling, wireline and core logging) and hydraulic tests in order to (1) image the saline/freshwater interface, (2) obtain an improved understanding of the intrusion process and its seasonal variation and (3) generate detailed and realistic models of a coastal aquifer. The Andarax river basin is an alluvial valley situated in one of the most arid regions in Europe. Its infrequent and irregular precipitation determines the regime of land use and groundwater abstraction. The Lower Andarax catchment serves as a test area for the project "Sustainable Management of Water Resources by Automated Real-time Monitoring (ALERT)" under the European Union Sixth Framework Programme, which aims to develop strategies for monitoring and managing vulnerable coastal zones. A number of manual ERT surveys conducted in the Andarax riverbed over a period of several months have revealed the shape of the mixing zone at high resolution. Present-day seawater intrusion appears to be confined to the shallow Quaternary part of the aquifer, where a sloping front has been detected down to depths of 70- 80 m over a distance of approximately 1300 m from the ...