Isotopic study of water resources in a semi-arid region, western Iraq

Hydrochemistry and stable isotopic technique were used in studying the water resources interaction in a semi-arid area, western Iraq. Throughout Iraq, 28 groundwater samples, 7 surface water samples from the study area, and 18 rainwater samples were analyzed for H-2 and O-18 stable isotopes and hydrochemical analysis. In this study, the temperature, altitude and continental effects on the isotopic composition of rain water in Iraq were studied. The results show that isotopes content in rainwater, in the current study, increases with increasing temperature and a good correlation exists between increasing latitude with decreasing delta O-18 values. Rainwater isotopes show evidence of temperature effect and continental effect associated with altitude effect. Generally, due to variation in temperature and altitude throughout Iraq, the values of isotopic composition of rainwater range from (-7.25 aEuro degrees) to (-2.79 aEuro degrees), and from (-45 aEuro degrees) to (-9.7 aEuro degrees) for delta O-18 and delta D, respectively. The similarity of isotopic composition of water of the Euphrates River and Haditha reservoir with that of groundwater taken from neighbor wells gives indication that intermixing between them is exist, while the groundwater of the wells far from the surface water resources is mostly affected by rainwater.