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Regional study of hard rock aquifers in Alentejo, South Portugal: methodology and results
| Content Provider | Semantic Scholar |
|---|---|
| Author | Chambel, António Duque, J. G. S. Nascimento, João Soares, Rodrigo P. |
| Copyright Year | 2007 |
| Abstract | A B S T R A C T Between 1997 and 2001 a Project called “Study of the Groundwater Resources of Alentejo Region” (ERHSA) was carried out in the region of Alentejo, southern part of Portugal. Great part of the area corresponds to igneous and metamorphic hard rocks. The exceptions are few areas of partly karstified crystalline limestones and a belt of sedimentary rocks on the western side. During ERHSA more than 7,000 data points were inventoried in hard rock aquifers. This extended study confirmed some results of previous studies, namely regarding the Gabbros of Beja Aquifer, and detected new productive or potentially productive areas within this region, namely the aquifers of the Charnokites of Campo Maior and Elvas, Pavia-Mora and the EvoraMontemor-Cuba. These last two systems mainly occur in gneissic or gneissic-migmatitic rocks, metamorphic volcanic-sedimentary complexes, and some tonalitic rocks. The difference between the hard rock aquifers and the less productive sectors are clearly related with the intensity of the fracturing net and the deep and type of the weathering layer. This distinguishes the gabbros and other basic or intermediate rocks (more productives) from the less productive granites. The weathering layers of the first ones can go to 30 m deep, against the normal 2 m in granites. The groundwater facies are mainly bicarbonate, except on the South part of Alentejo, where it is chloridebicarbonate. The main cations are the magnesium, calcium and sodium, by this order, having most part of these waters a mixed cation composition between three or two of them. The Northern part of Alentejo has waters with low levels of mineralization (average less than 400 S/cm of EC). On the contrary, the South part has clearly the most mineralized waters (average more than that 1,300 S/cm of EC). The future main task will be to conduct aquifer tests in order to have more hydrogeological parameters (transmissivity, permeability, and storage values), and try to understand the relation between instant yields, steady state flow, abstraction and aquifer parameters. |
| File Format | PDF HTM / HTML |
| DOI | 10.1201/9780203945650.ch4 |
| Alternate Webpage(s) | http://home.dbio.uevora.pt/~mmorais/docs/_20060926%20FIN_CHAMBEL_6_REV_3_a.pdf |
| Alternate Webpage(s) | https://doi.org/10.1201/9780203945650.ch4 |
| Language | English |
| Access Restriction | Open |
| Content Type | Text |
| Resource Type | Article |
