Hydrogeochemical mechanisms and recharge mode of the aquifers under semiarid climate from Morocco

Comprehensive investigations of groundwater were performed in the Ouazzi Wadi area, north part of Essaouira basin, Western Morocco. In the present investigation, hydrogeochemical data together with environmental stable (18O, 2H, 13C) and radioactive (3H and 14C) were used to get an insight into the processes controlling groundwater mineralization and their recharge modes. Hydrogeochemical approach revealed that the observed groundwater mineralization is linked to (1) dissolution phenomenon of evaporitics minerals (halite, gypsum, and anhydrite) and of carbonates minerals (dolomite), (2) cations exchange processes, and (3) marine effect. Groundwater quality for drinking purpose has been evaluated and compared to WHO standards; the obtained result shows that the consumption of groundwater in the study area requires a treatment before use as drinking water. As for irrigation purpose, using USSL and Wilcox diagram, groundwater remains suitable for plants supporting high salinity. Data inferred from isotopic approach indicated that (1) the groundwater samples are of a meteoric origin and the recharge of the aquifer is assured by direct infiltration of precipitations without notable evaporation, (2) the recharge of aquifers is assured at the Sebt Kourimat region, near the samples 7, 8, and 9, where the high tritium contents are observed, (3) the age evaluations using radioisotope techniques vary between actual age and Pleistocene.