ISOTOPES TRACING THE WATER CYCLE IN THE PAMPEANO AQUIFER AT THE SOUTHEAST OF BUENOS AIRES PROVINCE, ARGENTINA

DANIEL EMILIO MARTINEZ; ORLANDO MAURICIO QUIROZ LONDOÑO; HECTOR MASSONE; DAPEÑA CRISTINA

Mónaco

Simposio; Isotopes in Hydrology, Marine Ecosystems and Climate Change Studies; 2013

IInternational Atomic Energy Agency

A sedimentary sequence of loess-like Quaternary deposits, from few m to about 100 m thick, covers about 1,500,000 km2 in the Argentine Pampas. Despite of according its texture these deposits have been characterized as aquitard in some areas, the Pampeano sediments constitute the main groundwater resource for the sustainability of the agricultural production in Argentina. An isotope hydrology survey was carried out on a 10,000 km2 catchment covered by the Pampeano sediments in order to improve the understanding of the hydrological cycle. Rainwater has been collected and analyzed during 5 years at three points in the catchment, streamwater is continuously sampled weekly at three points in the main river since 2005, and many groundwater samples have analyzed for stable isotopes. Also about 50 3H data have been obtained. Results show seasonal effect in precipitation and the weighted average values as characteristics recharge water. Groundwater is quite homogenous in isotope composition indicating a dispersive conceptual flow model. Dominance of baseflow in streamflow composition is another of the conclusions of the study.