Identifying the origin of groundwater salinization in the Bokoya massif (central Rif, northern Morocco) using hydrogeochemical and isotopic tools

The recurrent drought in the Rif region, Northern Morocco, and specifically the Bokoya massif, has led to significant exploitation of groundwater to meet human and socio-economic objectives. In this context, a hydrochemical, geochemical, and isotopic tools has been carried out to determine the origin of dissolved elements and the processes contributing to the increase in salinization of groundwater. To achieve this objective, physico-chemical analyses of the water were carried out on 96 samples (81 wells and 15 springs), taken April 2018. The results show that the groundwater samples studied are characterized by a medium to high salinity, which can exceed 8000 μS/cm. Spatial distribution of physico-chemical parameters are consistent with the distribution of the rocks from Triassic formations. Our results also show that the salinization is probably due to the dissolution of evaporate rocks and ion exchange with precipitation of carbonate minerals such as calcite and dolomite. The stable isotope contents vary from −6.69 to −4.84‰ for δ 18 O and −42.6 to −30.1‰ for δ 2 H, indicating an altitude of recharge for most of the springs between 350 and 750masl. Exceptions to this are likely to have recharged from the flysch of Tizirene at altitudes higher than 1000masl, and following an altitudinal gradient of 0.27‰ per 100 m.