EL TRITIO COMO TRAZADOR DE LA DESCARGA DE AGUA SUBTERRÁNEA EN LA CUENCA DEL RÍO QUEQUÉN GRANDE, BUENOS AIRES

ALCARAZ, EMILIANO; BASALDUA, ALEJANDRO; QUIROZ LONDOÑO, MAURICIO; DAPEÑA, CRISTINA; COPIA, LORENZO; MARTINEZ, DANIEL E.

Actas del XI congreso Argentino de Hidrogeología: agua subterránea, el agua que no se ve

Ediuns

Lugar: Bahia Blanca; Año: 2022; p. 125 - 133

Tritium is a tracer that is ideal for hydrological applications as it is part of the water molecule. In addition to its use to determine ages, residence time, etc., it is another tool for hydrograph separation. In the Quequén Grande River watershed, a total of 60 existing tritium analyses were used, in addition to previous background data (chemical data, stable isotopes, hydrological modelling), to verify the validity of the same in the input to the system and ranges of groundwater ages. The separation of the hydrograph was carried out after a storm event in three previously defined sites in the drainage network, resulting in values consistent with previous studies, having estimated a 50% base flow in the composition of the main course (Quequén Grande River), 19% in the same upriver and 35% in a tributary (Arroyo Tamangueyú), the latter two being control sections of two different sub-basins. The surface runoff component and the groundwater discharge component (base flow) were identified as extreme members using the tritium content, thus obtaining the proportion of groundwaterbefore an event, this being of the order of 70% in the encounter of the main course with the estuary, which is compatible with previous hydrological modelling. Similarly, it has been possible to determine the response time to storms at these points, being approximately 2 days in the main section and 9 days in the control sections of the two sub-basins.