HYDROGEOLOGICAL AND HYDROGEOCHEMICAL CHARACTERIZATION OF THE UNCONFINED AQUIFER IN THE FLUVIO-EOLIAN PLAIN OF CORDOBA (ARGENTINE)

F. BECHER QUINODOZ; L. MALDONADO; MÓNICA BLARASIN; LUTRI VERONICA; A. CABRERA.; GIULIANO J; E. MATTEODA

HYDROLOGY RESEARCH

I W A PUBLISHING

Año: 2019 vol. 50 p. 725 - 743

0029-1277

The studied area, a vast plain located in the South of Córdoba (Argentine), presents a relief resulting from the juxtaposition of an eolian and a fluvial system. The objective of this work was to characterize the unconfined aquifer from a dynamic and a geochemical point of view, establishing relationships with lithological and geomorphological features. Statistical multivariate analysis (Q mode) of the hydrogeochemical data is a significant element of this characterization. The unconfined aquifer presents variable hydraulic gradients and groundwater velocity, both conditioned by the local relief and lithology. The aquifer showed a varied spatial geochemical pattern with fresh to salty water (0.4 to 10.0 g/L) and sodium bicarbonate to sodium chloride geochemical types, in some places of mixed anionic type. The statistical analysis showed 2 groups. Group 1 links salty-brackish groundwater of sulfate and chloride type with specific geomorphological units (longitudinal dunes and lowlands with locally outcropping water). It represents evolved groundwater coming from intermediate and regional flows related to lower gradients and flow velocities. Group 2 links fresh groundwater of bicarbonate type with active dunes and the fluvial strip with paleochannels. In these sites, where coarser sediments prevail, local groundwater flow cells develop as result of recent recharge, leading to greater groundwater velocity and decreasing the transference of ions to solution. These results allow us to identify the most promising areas to carry out future local studies, contributing to a deeper assessment of groundwater aptitude and the quantification of freshwater resources.