Groundwater quality in semi-arid environments (Essaouira Basin, Morocco)

Abstract

Hydrochemical, isotopy, and geostatistical approaches have been used to highlight the processes that control groundwater salinization in the detrital aquifer of Essaouira (Morocco). The hydrogeochemical approach shows that: (i) The dissolution of halite, gypsum, and/or anhydrite would contribute to the salinization of groundwater, (ii) the basic-exchange and marine intrusion phenomena are generally responsible for the wide variation in cation concentrations in groundwater. The use of this water for drinking purpose requires treatment before its use. For irrigation purpose, groundwater of the studied aquifer remains suitable for plants supporting high salinity. The nitrate contamination study shows that highest concentrations could be explained by: (i) the high concentration of tourism activity (Sidi Kaouki zone), (ii) the absence of sanitation network and wastewater treatment plant, and (iii) waste from livestock during watering. The stable isotope contents show that (i) Plio-Quaternary aquifer recharge is provided by the direct infiltration of Atlantic precipitation and (ii) the groundwater of the study area has undergone evaporation phenomena and marine intrusion. While the Geostatistics technique confirmed the results obtained by the hydrogeochemical and isotopic approach, highlighting the processes controlling the groundwater mineralization of the study area. However, the results of this paper can be used for better and realistic management of the water resource.