Stable isotopic technique and hydrochemistry was used in studying the water resources interaction of near Haditha Reservoir area, western Iraq. Throughout the study area, 14 groundwater samples (Bashina, Zwachi springs and Wells), 8 surface water samples from the study area, and 7 spring samples were analyzed for 2H and 18O 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 climate of the study area is classified as semi-arid to arid region. The results show a variation in the isotopic values of Haditha reservoir and Euphrates river. This variation is due to the effect of the low surface area and the low velocity of water of Haditha Reservoir on the amount of evaporation, compared with the high velocity and the large surface area of Euphrates river. There was a variation in the isotopic values between Bishina and Zwachi springs, due to two factors that appear to modify the isotopic signatures of the springs, namely the lack of hydraulic connection between the springs of Bishina and Zwachi, meaning that they recharge from different sources. The changes in oxygen isotope composition of the groundwater between a deep reservoir and the springs (Bishina) may be caused by the dilution with near surface waters (Haditha reservoir) with different oxygen isotope compositions. The variation in the isotopic content in the studied area indicated that there are various origins of springs recharge and a different interactions of the multiple sources of springs with the mutli-depths of springs water.
