Hydrochemistry and geothermometry of thermal water in northeastern Morocco

Thermal water in northeastern Morocco is a promising, sustainable resource of energy. To date, thermal water has not been used as a source of renewable energy in Morocco as no clear strategy has yet been developed for its use. In this study, 10 samples (boreholes and springs) of thermal water distributed within the basin of the Moulouya River were assessed, and their physical and chemical parameters (such as temperature, pH, electrical conductivity (EC), and major ionic composition, including the K+, Na+, Ca2+, Mg2+, Cl−, SO42−, NO3−, NO2−, NH4+, H2PO4−, CO32−, and HCO3−) were measured. The results show that the temperature, pH, and EC range between 28 and 55 °C (as measured in field), 5.46 and 7.50, and 478 and 15,580 µS/cm, respectively. Furthermore, the results indicate the presence of four main hydrogeochemical facies dominating the hydrogeological system, which are Na–Cl, Na–Ca–Cl, Ca–Mg–HCO3, and Na–Ca–HCO3. The geothermal reservoirs of the different samples were investigated by the means of several geochemical methods, including the Giggenbach Na–K–Mg diagram, two geothermometers (Na–K–Mg), and the determination of the saturation index. We noticed different estimated geothermal reservoir temperatures over the range 80–170 °C.