The large wetland area with its numerous aquifers in the extreme south of the Ljubljana basin is a very important water resource with very complicated hydrological structure. Tritium and oxygen isotope composition were therefore determined, beside others parameters such as concentrations of gamma-ray emitters and geochemical parameters (Ca2+, Mg2+, Na+, K+, Cl-, SO42-, NO3-, HCO3. Conductivity, pH, H-2). Obtained results confirmed existance of many different types of groundwaters in the basin and clarify the status of lower aquifers.
The article presents the application of isotope methods in the study of groundwater transport processes in the unsaturated zone of the Selniška Dobrava coarse gravel aquifer. The estimation of groundwater flow characteristics was based on experimental work in lysimeter. Based on long-time isotope investigations with the use of lumped parameter models, mean residence time and mean matrix flow velocity in the aquifer unsaturated zone were calculated.