title: Isotopic and hydrochemical approach to the functioning of an aquifer system in the region of Marrakech (Morocco).
abstract: A geochemical and isotopic (water and dissolved sulphate) study was performed on groundwater in the region of Marrakech, Morocco, with the aim of better understanding the regional hydrogeological system in order to improve water resources management. Significant differences in stable isotope contents and chemical compositions were observed between groundwater collected in the northern part of the region (Jbilets massif), where the basement schists outcrop, and that sampled in the southern part (Haouz basin), where the basement schists are overlaid by Plio-Quaternary deposits. The stable isotope composition of the groundwater showed that in the southern part the aquifer is mainly recharged from high-altitude precipitation over the High-Atlas Mountains, which may reach 600 mm per year or more, whereas, in the northern part, it is only recharged by lower-altitude local precipitation, which does not exceed 240 mm per year. Because of this limited supply, the groundwater flux in the northern compartment is much lower than in the southern compartment. This affects the water-rock interaction and the modalities of groundwater mineralization: the schist alteration is more developed in the southern compartment than in the northern one, leading to different behaviours of the conservative elements dissolved in groundwater. The observed geochemical and isotopic zonation of the studied area corresponds to a hydrogeological compartmentalisation, where the wells located in the north of the area generally produce less water than those located in the south of the area.
authors.affiliation: Lab. IDES, Université Paris-Sud, CNRS UMR 8148, Orsay, France.
authors.forename: Anasse
authors.initials: A
authors.lastname: Ait Lemkademe
authors.forename: Jean-Luc
authors.initials: JL
authors.lastname: Michelot
authors.forename: Abdelfattah
authors.initials: A
authors.lastname: Benkaddour
authors.forename: Laoucine
authors.initials: L
authors.lastname: Hanich
authors.forename: Ahmed
authors.initials: A
authors.lastname: Maliki