Groundwater residence time in the Pampeano aquifer: Multilevel piezometers and multitracers study.

MARTINEZ, DANIEL E.; FOURRE E.; QUIROZ LONDOÑO, M.; JEAN-BAPTISTE, P.; GLOK GALLI, M.; DAPOIGNY, A.; GRONDONA S.

Viena, austria

Simposio; International Symposium on Isotope Hydrology: Revisiting Foundations and Exploring Frontiers.; 2015

The Pampeano Aquifer is an unconfined hydrogeological unit covering a large area in the Argentine Pampas. In order to improve the groundwater residence time knowledge four sets of three nested multilevel piezometers were drilled in selected locations at two catchments in the Pampas plain. Groundwater samples at three different depths have been took and transit time was determined through CFCs and 3H/3He measurements. CFCs and 3H/3He obtained residence times are in relative good agreement, ranging between 20 to more than 60 years. Clear trends in residence time increase with sampling depth are observed. Differences among catchments and recharge or discharge areas can be recognized. It is noticeable that instead even at the shallowest sampling depths collected in this study, water residence time is in the order of 20 years.