USE OF COMBINATIONS OF LUMPED-PARAMETER MODELS TO INTERPRET GROUNDWATER ISOTOPIC DATA

The method of lumped parameter models in the field of isotope hydrogeology mainly includes the investigation of the age structure of the groundwater in the aquifer concerned. Results of such applications can be used in the simulation of mass transport or for the assessment of groundwater vulnerability to anthropogenic pollution. Commonly, such investigations are based on data of environmental isotopes (e.g., H-3, C-14, Ar-39, Kr-85) or other tracers. In this context, the lumped parameter models do not make any assumptions concerning specific pollutants, but their advantage over discrete numeric simulation approaches is that they need relatively few parameters. In some circumstances, the combination of several lumped parameter models permits a better approximation of the real situation by the model assumptions. However, the additional parameters required are often unknown. The user-friendly computer program presented in this paper allows the selection from more than 30 model combinations and calculates up to two free model parameters as well as further quantities related to the vulnerability. It has several functions for pre-processing and post-processing. In the example of application, some of the program features and possibilities are presented.