Coudrain A., Talbi A., Loubet M., Gallaire Robert, Jusserand C., Ramirez Edson, Ledoux E. (1999). Isotopic and chemical composition of groundwater in the Bolivian altiplano, present space evolution records hydrologic conditions since 11000 Yr. In :
Symposium. La Paz : ORSTOM, 9 p. multigr. Symposium, Vienne (AUT), 1999/05.
Titre du document
Isotopic and chemical composition of groundwater in the Bolivian altiplano, present space evolution records hydrologic conditions since 11000 Yr
Année de publication
1999
Type de document
Littérature grise
Auteurs
Coudrain A., Talbi A., Loubet M., Gallaire Robert, Jusserand C., Ramirez Edson, Ledoux E.
Source
La Paz : ORSTOM, 1999,
9 p. multigr.
Colloque
Symposium, Vienne (AUT), 1999/05
The phreatic aquifer of the central Altiplano shows a Cl concentration that increases from 0.5 meq l-1 upstream to 150 meq l-1 downstream. The main outflow process from the aquifer is the upward flow E into the unsaturated zone associated to evaporation close to soil surface. A relation has been established for any arid zone areas on the base of isotopic profiles: E (mm yr-1) = 63 Z-l.5 where Z (m) is the water table depth under soil surface. The aquifer under study may have acquired its high chlorine content during last lacustrine phase (Tauca, 12 ka BP). Arguments for this hypothesis are: (i) maximum level of the lake (3780 m) higher than present soil elevation in the area, (ii) same order of salinity in the paleolake and in the more saline groundwater, (iii) weak molar ratio of Li/Cl in saline groundwater and in the Tauca, (iv) modeling of Cl transport over 11000 years consistent with observed spatial evolution of Cl in groundwater. To this scenario, might be superimposed the assumption of a delay for the convective transfer of salt towards south by the coupled effects of accumulation of salt in the unsatured zone by evaporation from the aquifer during thousand or so years, and tof the subsequent return of this salt downwards to the aquifer during some short rainy periods. The 87Sr/86Sr, major and trace element compositions of surface and groundwater support this proposed scenario (Résumé d'auteur)
Plan de classement
Fonctionnements des systèmes d'eau et modélisation [062EVAEAU02]
Descripteurs
AQUIFERE ; EVAPORATION ; COMPOSITION CHIMIQUE ; SALINITE ; ISOTOPE ; ZONE ARIDE ; LAC ; HAUTE ALTITUDE ; HYDROGEOLOGIE ; PALEOLAC
Description Géographique
BOLIVIE
Localisation
Fonds IRD [F B010026665] ;
La Paz
Identifiant IRD
fdi:010026665
