Hydrogeochemical study of the clastic aquifer in the Umm Gudair field, Kuwait

The Kuwait Group aquifer is a major source of brackish groundwater in the State of Kuwait. The aquifer ranges in thickness from 150–400 m. In the Umm Gudair well field, the water has total dissolved solids ranging from 3,130 to 4,790 mg/l. According to the Sulin classification, all the Kuwait Group aquifer samples are characterized as Cl–Mg or Cl–Ca genetic water types. The chemical data indicate that the aquifer is generally in equilibrium with respect to calcite, dolomite and gypsum but undersaturated with respect to halite and polygorskite. The study has indicated that de-dolomitization is the major geochemical process controlling the chemistry of this aquifer, increasing the major complexes of sulphate and carbonate due to the dissolution of gypsum. The ratio of Cl/Na indicates that the Na⁺ ions have been taken from the Kuwait Group aquifer by reverse ion exchange.