Hydrochemical, Isotopic, and Geophysical Studies Applied to the Evaluation of Groundwater Salinization Processes in Quaternary Beach Ridges in a Semiarid Coastal Area of Northern Patagonia, Argentina

CAROL E.; PERDOMO S.; ALVAREZ M. P.; TANJAL C.; BOUZA P.

WATER MDPI

MDPI Multidisciplinary Digital Publishing Institute

Año: 2021 vol. 13

2073-4441

Quaternary sea level fluctuations have led to the development of beach ridges on many South Atlantic coasts. The objective of this paper was to asses from lithological, hydrochemical, isotopic, and geophysical studies the salinization processes affecting groundwater stored in Pleistocene and Holocene beach ridges of the northern Patagonian coast. A hydrogeomorphological characterization of the area was performed using digital elevation models, the interpretation ofsatellite images, and field studies. Vertical electrical soundings were performed on transectsrunning perpendicular to beach ridges in order to define variations in the freshwater‐saltwaterinterface position. The salinity, chemistry, and stable isotopes of the groundwater were analyzed.The results demonstrated that the groundwater salinization of Pleistocene ridges responds toprocesses associated with the geological‐geomorphological evolution of the area. The cementationof these surface sediments limits rainwater infiltration, which consequently prevents the development of freshwater lenses. This suggests that saline water is the result of ancient marineingressions. Freshwater lenses develop in Holocene beach ridges; however, slight water salinizationis detectable in the most populated areas as a result of intensive exploitation. The data provided areuseful for freshwater resource prospection along the arid coast of Patagonia, where beach ridgedeposits abound and populations experience serious drinking water supply problems.