Youssef Hsissou

Utilisation du rapport Br/Cl pour déterminer l'origine de la salinité des eaux souterraines: exemple de la plaine du Souss (Maroc)

Abstract The use of bromide anion contents is an essential complement to chloride measurements in order to explain the salinity anomalies in groundwaters. Thanks to the relationship Br = ƒCl) and to the molar ratio Br/Cl, it allows marine influence areas (the Ocean, precipitation, aerosols, sedimentary paleosalinity) to be distinguished from evaporitic or anthropogenic influence areas, which are impoverished in Br as opposed to the oceanic domain. Applied to the Souss alluvial plain, and thanks to this methodology, we can interpret phenomena which are responsible for conductivity anomalies in groundwaters: present salt encroachment, sedimentary paleosalinity or wastewaters downstream; evaporites, recycling of irrigation waters in the mean Souss.

Détermination des modalités de recharge des aquifères par le biais des traceurs chimiques et isotopiques. Cas de la zone de contact Haut Atlas occidental – Plaine du Souss (SW du Maroc)

Determination of the origin of recharge of the unconfined aquifer in the right side of the Souss wadi between Agadir and Taroudant (South-western of Morocco) was based on the use of hydrochemical and isotopic analysis of groundwater, surface water and springs of the contact zone between the High-Atlas Chain and the Souss plain. The correspondence in the space evolution of the various chemical elements of evaporitic origin (SO 4 2- , Cl - , Sr 2+ ) in groundwater, piedmont springs, and surface water reveals the existence of recharge water from the adjacent High-Atlas Chain. The various recharge modes of the different aquifers (High Atlas and Souss plain) determined by isotopic analysis, shows that the source of groundwater for the unconfined Souss aquifer seems to be composite between a direct infiltration on the High-Atlas tributaries and a remote recharge from the bordering High Atlas aquifers.