. Estudio Isotópico Preliminar del Acuifero del Valle Argentino, provincia de La Pampa, Argentina.

DAPEÑA, CRISTINA; SCHULZ, CARLOS J.; PANARELLO, HECTOR; DORNES, PABLO; DALMASO, GABRIELA

Mar del Plata, provincia de Buenos Aires

Congreso; XXXII IAH & VI ALHSUD ?Groundwater and Human development?; 2002

AIH , AIH-GA y ALHSUD

The Valle Argentino is a geomorphological unit which extends from Chacharramendi (La Pampa province) to Arano (Buenos Aires province).  Its main characteristic is the presence of a detritic aquifer located in the middle part of the valley.  A set of shallow saline lakes developed along the borders constitutes the discharge area.  The groundwater resources comprise the only source of water supply in the zone.  This work aims to contribute to the study of the groundwater origin and recharge mechanisms using  the environmental isotopes 2H, 18O and 3H.  Two station for the collection of monthly total precipitation were placed at Padre Buodo and El Escabel, sites.  A seasonal and continental isotopic pattern were detected at Padre Buodo. These "effects"  lead to a depleted isotopic composition that is also coincident with the recharge months.  Two evaporation lines were built.  One corresponds  to waters recharging the sandy sediments and the other  to  waters infiltrating across the "tosca" and to the discharge areas.  Variations in groundwater isotope content may be due to evaporation prior infiltration, selective recharge and mixing with irrigation water.  The great variability of 3H concentration responds to the same mechanisms, mainly those which involve the transit times