One of Iraq’s most significant groundwater-bearing limestone aquifers is the Dammam Formation. The aquifer groundwater has been studied hydrogeochemically. It is suitable for irrigation, as indicated by sodium adsorption ratio (SAR) and total dissolved solids (TDS), which are 4.15 and 1971 ppm (in average) respectively. Through the vision of the Stiff diagram, the predominant ions are Cl-, SO4 2+ and Na+ while the HCO-3 and Mg2+ are relatively poor. There is plenty of flowing wells in the study area in Najaf Governorate producing groundwater from the Dammam aquifer. In recent years, many wells have been drilled in an irregular pattern for forming fish breeding lakes. These lakes’ water drains 4.715 m3/s into the Najaf depression by Wadi Al- Khur and artificial channels, where it mixes with brine water, rendering it useless. This lead to the exhaustion huge amount of precious groundwater resource. Many signs that confirm the Piezometric pressure drop and groundwater levels descent in the Dammam aquifer in the region. The groundwater flow has been halted in several flowing wells in the study area especially in Wadi Al-Khur due to the exhaustion of the reserve and a decrease in the level of the hydrostatic pressure of the aquifer. A significant decline in values transmissivity and specific capacity of the Dammam aquifer when compared with previous studies in the years 1996 and 2009. Through observation of the monitoring well (W/7), a decrease in groundwater levels of flowing wells in the study area.

Groundwater is the main source of sustaining life in the Najaf Desert that helps sustain human and animals’ lives. The aquifer of the Dammam Formation is considered as the main source of groundwater in the study area. The isotope elements have been used as a geochemical indicator to determine the age, direction of flow and the effect of rainwater of this area. The values of stable isotopes δ18O and δ2H range between -2.56‰ to -1.99‰, and between 7.12‰ to -4.84‰ with an average of -2.32‰ and -6.20‰ in rainfall respectively. Their values range from -3.26‰ to -2.01‰ for δ18O, and from -27.00‰ to -16.21‰ for δ2H with an average of -2.70‰ and -22.27‰ in the Dammam groundwater respectively. The groundwater is old and does not mix with new water, because tritium has not been not detected. Furthermore, the δ18O and δ2H values show that the rainwater, which feeds the aquifer does not come from the continental lands. They represent a humid and cold climate, as well as a considerable amount of rainfall in the past. Analyses of 14C indicate that the groundwater dates back to approximately 4176 years ago. The groundwater is moving from the west and southwest directions to the north and northeast directions.