Hydrochemical and geothermometry characterization for a geothermal system in semiarid dry climate: The case study of Hamma spring (Northeast Algeria)

Abstract

Climate change has increased the odds of worsening drought in arid and semiarid dry regions of North Africa. Although the thermal waters have a minimal influence on the yield of aquifers systems, these resources have a great socio-economic value, being widely used for various rheumatologic, dermatologic and psychiatric treatments. Our study aims to characterize the physicochemical parameters and geothermal properties of El Hamma hydrothermal systemin northeastern Algeria. We collected twelve water samples during April 2019 to identify the origin of the thermal groundwater and to evaluate the reservoir temperature in the geothermal system; based on major chemical constituents concentrations, saturation indices, and chemical geothermometer temperatures. We measured temperature, pH, and electric conductivity (EC) conventionalparameters. The temperature of the thermal water sample reaches 52.8 °C, the pH is slightly alkaline, with EC up to 3100 μS/cm.We applied the diagram program to determine the hydrochemical facies, and the equilibrium state of the solid/liquid phase. We used Geothermometers to determine the origin, and temperature at depth of thermal waters. The facies are chlorinated and sodium sulphates; which is mainly related to the dissolution of evaporitic minerals and the weathering of silicates. The geothermometers have given temperatures ranging from 80.73 °C to 126.63 °C for the thermal reservoir. The results have identified the Jurassic limestone at more than 2300 m depths as the main thermal reservoir. Moreover, the application of the International Institute for Geothermal Research (IIRG) diagrams to the hot waters has shown a "γ" diagram type, leading to confirm that the hot solutions are of deep origin, with waters circulating in the basement and carbonate formations.