Groundwater hydrodynamics of the sandy coastal aquifer of southwestern Buenos Aires, Argentina. Punta Alta - Monte Hermoso sector

Abstract

Due to their hydrogeological characteristics, dune sectors have a particular hydrodynamic behavior. The high permeability of the sediments, together with the topography of the dune fields, favor both the infiltration of rainwater and the absence of surface drainage networks. Theseareas, where the water table is shallow, are dominated by short-distance or local groundwater flows, superimposed tointermediate or regional flows. The objective of this work is to contribute to the hydrogeological knowledge of the free aquifer, by means of the generation and analysis of hydrodynamic maps and profiles, which will be used as a tool for the management of the resource. The hydrodynamic model of the phreatic aquifer was defined on the basis of data obtained from water point surveys carried out at a sampling density of 1 point every 10 km2. The unsaturated zone has an average thickness of 5 m, and hydrodynamically two sectors with distinctive behaviors were identified, related to the dominant topographic characteristics. The first, corresponding to the western sector of the area, has a parabolic-cylindrical water table morphology, with a north-south flow direction and discharge at the sea front. The second, located to the east, presents a west-east groundwater divide in the center of the dune chain, generating divergent flows to the north and south of it.