Origin of salinity of the shallow aquifer of Guelmime, south Morocco: Hydrogeochemical study

The economy of the Guelmime region is primarily dependent on agriculture and herding. Population growth and economic development result in an increase in water demand and the generation of additional pollution sources. The shallow aquifer of Guelmime is the main reservoir for drinking water supplies and plays a major role in the local economy. The aquifer corresponds geologically to a tectonic depression with Plio-Quaternary fill. In the aquifer, groundwater is characterized by chemical facies of type: Mg-HCO3, Mg-Cl and Na-Cl. The spatial distribution of total dissolved solids (TDS) shows a widening gradient with an increase in salinity downstream of the Oumlaachar and Seyyad sub-basins. The primary processes controlling groundwater evolution in the basin-fill aquifer, using hydrogeochemical analysis of the behaviour of major ions, are: (i) dissolution of evaporites of the Plio-Quaternary formations, (ii) dedolomitization phenomena, and (iii) the return flow of irrigation.