Resumen

BECHER QUINODOZ, Fátima Noelia; BLARASIN, Mónica. T  y  PANARELLO, Héctor O. Modelado geoquímico e isotópico de las relaciones agua superficial-subterránea en la planicie arenosa del sur de Córdoba. Rev. Asoc. Geol. Argent. [online]. 2015, vol.72, n.4, pp.506-518. ISSN 0004-4822.

The sandy plain of the south of Cordoba is a palimpsest resulting from an Aeolian System (“Pampean Sand Sea”) and the Quinto River system’s juxtaposition. The aim of this work is to carry out the dynamic and geochemical characterization (general and isotopic) of surface water-groundwater relationships, validating with a numerical model. The Quinto River, with headwaters in the San Luis Mountains, develops its middle basin in the study area, registering flow variations between winter and summer. The average surface water velocity is 0.8 m/s and the geochemical type is sodium sulfate. The unconfined aquifer presented variable hydraulic gradients, low water velocity (0.2 m/d) and a complex geochemical pattern (sodium bicarbonate, sulfate or chloride types). Considering the hydraulic connection between the two hydrological systems (a predominantly gaining river) a dominance of surface water in summer is detected. Thus, surface water dilutes by hydrodynamic dispersion the salts supplied by the aquifer, due to differences in water velocity in both hydrological systems. Isotopes results show that the river and the aquifer lay on an evaporation line with origin in the upper basin water isotope composition, which indicates provenance. The low slope of the line indicates river-aquifer mixing processes. Thus, in Cordoba Province, it was observed the prevalence of surface water in summer (72 %), including contribution from dams, while the base flow is dominant in winter (82 %). This basin constitutes a paradigmatic case of natural and anthropogenic constraints, whose functioning does not recognize political boundaries, indicating the usefulness of inter-jurisdictional studies.

Palabras clave : Unconfined aquifer; Quinto river; Geochemical modeling; Stable isotopes.

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