Lischeid, G; Lange, H; Hauhs, M: Information gain by single tracers under steady state and transient flow conditions: the Gårdsjön G1 multiple tracer experiments., Tracers and Modelling in Hydrogeology, Proc. IAHS "TraM" 2000 Conference", 262, 73-77 (2000)
Abstract: Tracer experiments are a common method to obtain spatially integrated information about aquifer properties. However, the uncertainty of unique experiments can rarely be assessed. The Gårdsjön G1 roofed catchment was used to perform a series of steady state experiments with almost identical boundary conditions. Br, Cl, and 2H tracers were applied in parallel. Tracer breakthrough curves are modelled by a two region convection dispersion model. Parameter values determined by inverse modeling critically depend on the underlying assumptions. E.g., weather a tracer is conservative or not cannot be assessed based on the model only. Furthermore, in the case of the Br tracer our experiments exhibit a clear dependency on the temporal scale of the measurements. In spite of very similar boundary conditions, the shapes of breakthrough curves and the corresponding model parameter values of different experiments differ considerably. In addition, transit time probability for steady and transient flow conditions differ substantially.