Resumo

BERTOLA, Germán R.; ISLA, Federico I.; CORTIZO, Luis C.  e  TURNO ORELLANO, Horacio A.. Sedimentary model of the sandy barrier to the north of Villa Gesell (Buenos Aires province) for hydrogeological assessment. Rev. Asoc. Argent. Sedimentol. [online]. 2002, vol.9, n.2, pp.109-126. ISSN 1853-6360.

Cariló and Villa Gesell localities were constructed on a barrier younger than 1,400 years BP. Dealing with the stratigraphic and textural characteritics of this area, 15 holes were drilled to a depth of 40 m at the property projected as "Ciudad Marina de Port Dora". Three sandy strata were assigned to aquifers and test by pumping essays. These aquifers considered of hydrogeologic interest comprise the stratigraphical units called Punta Medanos, Pozo N°8 and Canal 5. The dune field is composed of transverse bodies oriented toward the north-northeast. Infiltration is uniformly distributed although at interdune ponds the water table is above the land surface. Water quality (temperature, pH, dissolved oxygen, turbidity) at the testing wells located close to the beach retrieves freshwater. In the sandy barrier from Villa Gesell and Cariló the sandy silts of hydrogeologic interest continue to depths below 40 m. The sedimentary record of the Eastern Barrier of Buenos Aires Province consists on a complex barrier (overlapping of barrier deposits of Quaternary age), modified during the Holocene transgressive-regressive cycle and where these transgressive and regressive processes are still being recorded at some locations (progradation of Punta Médanos, scarps of foredunes in Mar Chiquita). Considering the low density population of the area, precipitation is estimated as able to provide the volume of water needed during the summer season for the resort villages. Average trasmissivity is about 206 m²/day for the free aquifer and 130 m²/day for the semiconfined aquifers. Average permeability is 18.23 and 4.19 m/day at each type of aquifers.It is recommended to avoid the on-exploitation of the free aquifer in order to preserve their volumes, to prevent pumping cones and to avoid saline intrusions at the coast. The hydrogeologic reserves exceed the water volume supplied from the pampian silts (Buenos Aires formation) located to the west of the Route 11. The evaluation of these inputs of groundwater is recommended in order to better manage the semiconfined levels. Even though, recycling and reusing should be considered for the urban growth planing. At the coastal barrier, below the phreatic aquifer, a semiconfined horizontal level of variable thickness was recognised, and superimposed to a second semiconfined aquifer. This second semiconfined level with plane base and irregular top, is superimposed to a third semiconfined aquifer whose base was not drilled.

Palavras-chave : Sedimentary model; Stratigraphy; Hydrogeology; Cariló; Villa Gesell.

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