Hydrogeochemical investigation and groundwater quality in Essaouira region, Morocco

Abstract

Given the scarcity, or even absence, of surface water and the domination of the semi-arid climate in the coastal zone of the Essaouira basin (Morocco), the Plio-Quaternary, Turonian, Barremian–Aptian and Hauterivian aquifers represent the main source of water for fine consumption and agriculture. However, the study of their quality is a priority. So as to reach the objective of this study, the combination of the two hydrogeochemical and geographical information system tools was used. The results obtained showed that the facies characterising the Plio-Quaternary aquifer was a combination of Ca–Mg–Cl and Na–Cl, and that characterising the Turonian, Barremian–Aptian and the Hauterivian aquifer was a combination of Ca–Mg–Cl. However, flagship ions in the study area are Cl, Na, Ca and Mg. For consumptions purpose, the comparison of the concentrations of major elements with the standards of the World Health Organization showed that all the elements presented concentrations below the threshold, except for chlorides, the concentrations of which exceeded the threshold. For the agricultural purposes, the two Wilcox and United States Salinity Laboratory (USSL) diagrams, and the spatial distribution of parameters total dissolved solids, total hardness, permeability Kelly’s ratio, sodium hazard, sodium percentage and nitrates showed that the groundwater in the study area is adequate for persistent plants with a high to very high salinity tolerance.