Use of environmental tritium to study catchment dynamics: case study from the Danube River basin

Use of environmental isotopes, particularly, oxygen (O-18) and hydrogen (H-2 and H-3) offers unique methodologies for investigations related to rainfall-runoff relationships and catchment dynamics. Using long-term tritium (H-3) data in the Danube River, observed temporal variations in the river water have been simulated through a compartmental (mixing cell) modelling approach to estimate the fluxes of surface flow and groundwater to total river discharge and to characterize the transit time distribution of these component flows. The findings of this approach are compared to the results of an earlier simulation model based on the Artificial Neural Network (ANN) approach using the same long-term tritium data. The two approaches provide comparable results for the characteristics travel time of the water in the basin providing improved confidence for the results.