Evaluation of recharge origin of groundwater in the Alazani-Iori basins, using hydrochemical and isotope approaches

ანოტაცია

85 groundwater, stream water and lake water samples were analysed in 2013 for composition of major ions and isotopes ¹⁸O, ²H and ³H in the Alazani-Iori area, eastern Georgia. Three groups of groundwaters were identified, revealing the dominant evolution in mineralization from Northwest to Southeast, with major increase in the Shiraki syncline area. The geochemical patterns among these groups evolve from Ca(Mg)/HCO₃ type in the Kvareli aquifer to Na/SO₄(Cl) type in the Shiraki syncline. Almost all aquifers in the study area contain admixture of older waters recharged prior to the 1950’s or paleowaters with no Tritium and low d¹⁸O values between -11 and -13 per mil SMOW. Although most of the artesian boreholes are up to 500m deep, their groundwaters belong to different hydrochemical and isotopic groups and must be considered with respect to local stratigraphy. Whereas the groundwaters in the Alazani valley artesian aquifers are concluded to be of a good quality for drinking, it is recommended to enhance the use of waters from the karstic formations such as the Dedoplitskaro Plain for alternative drinking water sources in the Shiraki –Iori basin.