Caractérisation hydrochimique d’un complexe volcanique aquifère dans une zone de rift continental: le bassin de l’Awash moyen, Ethiopie Caracterización hidroquímica de acuíferos volcánicos complejos en una zona de rift continental: la cuenca media de Awash, Etiopía 埃塞俄比亚Awash中部盆地大陆裂谷带复杂火山含水层的水化学特征 Characterisazione idrochimica dei aquifer volcanic complessi nella zona rift continentali: Bacino del Awash Medio, Etiopia Caracterização hidroquímica de aquíferos vulcânicos complexos numa zona de rift continental: a bacia do Médio Awash, Etiópia

Furi, Wakgari; Razack, Moumtaz; Abiye, Tamiru Alemayehu; Sayfu Kabada,; Legesse, Dagnachew

Caractérisation hydrochimique d’un complexe volcanique aquifère dans une zone de rift continental: le bassin de l’Awash moyen, Ethiopie Caracterización hidroquímica de acuíferos volcánicos complejos en una zona de rift continental: la cuenca media de Awash, Etiopía 埃塞俄比亚Awash中部盆地大陆裂谷带复杂火山含水层的水化学特征 Characterisazione idrochimica dei aquifer volcanic complessi nella zona rift continentali: Bacino del Awash Medio, Etiopia Caracterização hidroquímica de aquíferos vulcânicos complexos numa zona de rift continental: a bacia do Médio Awash, Etiópia | Hydrochemical characterization of complex volcanic aquifers in a continental rifted zone: the Middle Awash basin, Ethiopia

2012

Furi, Wakgari | Razack, Moumtaz | Abiye, Tamiru Alemayehu | Sayfu Kabada, | Legesse, Dagnachew

The Middle Awash basin is an arid region in Ethiopia where surface waters are scarce and local communities are dependent on groundwater resources for water supply. The complex hydrogeological system of this basin has been conceptualized. Multivariate statistical analysis of hydrochemical variables and water isotopes were used to study the rock–water interaction, geochemical reaction processes and the hydrological link between aquifers. Groundwaters from aquifers of the high-rainfall plateau bounding the rift are slightly mineralized, as well as depleted in δ18O and δD, and contain 3H above 0.8 TU. This suggests a low degree of rock–water interaction and that groundwater is under recharge from heavy rain that falls on surrounding highlands. On the other hand, groundwaters from aquifers of the rift floor are highly mineralized and show slight enrichment in δ18O and δD with positive oxygen shift, but contain 3H below 0.8 TU. The positive oxygen shift in rift floor groundwaters may be caused by the isotopic exchange of oxygen between groundwater and aquifer materials during rock–water interaction, whereas the low 3H content could be due to the decay of tritium along relatively long flow paths. The approach utilized in this study may be applicable to understanding hydrogeochemical processes in other complex volcanic terrains.

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