Hydrogeochemical characterization of groundwater resources in Wadi Araba Basin, Southern Jordan

Abstract

AbstractGroundwater quality is an important factor that determines its usage for drinking and irrigational use. This study was carried out along the quaternary alluvial aquifer which extends along Wadi Araba groundwater basins, in southern Jordan. Chemical and physical parameters were measured and analyzed for thirty-seven groundwater samples collected from twenty-one wells in the study area during two periods in the year 2019; the spring season (April–May) was represented by fourteen samples and the autumn season (August–September) represented by twenty-three samples were collected to determine its suitability for drinking and irrigational purposes. The groundwater in the study area is generally of low alkalinity with an average pH value of less than 8 for both spring and autumn seasons. The water of the area is excessively mineralized due to salinity, and the increase in water salinity of the southern Wadi Araba basin is less expressed than in the northern part. The hydrochemical characterization shows that most wells of the study area are characterized by HCO3–Ca–Mg and HCO3–SO4–Ca–Mg types in the eastern escarpments of Wadi Araba (i.e., recharge area) and Cl–SO4–Na and Cl–Na types in the discharge area. There is no substantial change in the hydrochemical composition during the two seasons. Based on the Piper diagram, most of the groundwater samples (91.8%) belong to class “E” as “earth alkaline water with increased portions of alkalis with prevailing sulfate and chloride.” The Durov diagram reveals that most groundwater samples (62.2%) lay in the water genesis “field 6” which indicates that the water may be related to the reverse ion exchange of Na–Cl. The chemical composition of the water samples was compared with the drinking water standards of the World Health Organization and the Jordanian Standard. Groundwater from this area was not suitable to be a source for direct drinking based on total hardness and total dissolved solids. The dominant cation is sodium, while the dominant anion is chloride. The calculations of saturation indices for the two sampling campaigns for different minerals showed negative values of (SI) for carbonates minerals (anhydrite, gypsum, sylvite, and halite). This suggests that the groundwater in the alluvial aquifer is undersaturated with respect to these minerals in most of the study area. This is indicative of the fact that these minerals are undergoing the process of dissolution. The mineral saturation indices suggest that the dominating hydrochemical processes were dissolutions of evaporite minerals (halite and gypsum), carbonate minerals (such as calcite, dolomite, and rhodochrosite), the manganese oxide minerals (such as jarosite-K, hausmannite, pyrochroite, and pyrolusite) and reverse ion exchange.