Characterization and sensitivity analysis of tracer breakthrough curves with respect to multi continuum modeling
In order to support a sustainable use of water resources in hard rock aquifers, appropriate experimental and modeling techniques are essential. Multi continuum modeling as a compromise between detailed discrete modeling and rough estimations by analytical solutions, offers a solution by neglecting discrete effects while considering different hydraulic properties. In the scope of this work, characterization techniques are investigated in order to support the choice of an appropriate multi continuum model. Furthermore, sensitivity analyses for multi continuum models are developed to identify the relevant parameters and to explain the dominant flow and transport processes. In order to assess the transferability of insights gained from gas tracer experiments as performed within the Aquifer Analogue Project to water-saturated conditions, both numerical investigations for the water- and the gas-saturated case are analyzed. A double continuum model of the sandstone block investigated in the scope of the Aquifer Analogue Project is developed. Due to strong heterogeneities of the sandstone block, the flow and transport behavior cannot be represented satisfactorily. The model performance could be enhanced by adding discrete elements in order to account for the strong discontinuities found at the field site. A prognosis of the behavior of the water-saturated sandstone block would then be possible. This would create a link between the numerical analyses in this thesis to a real aquifer environment. The applicability of the approach to identify an appropriate model type for a system by means of key-figures to the two-dimensional case is investigated. It is demonstrated that due to the special characteristics of the dipole flow field, the tracer breakthrough curves for different model types are similar. It is thus more difficult than in the one-dimensional case to deduce the number and type of the components contributing to the transport processes from the shape of the tracer breakthrough curve. By means of the sensitivity analyses carried out in the scope of this thesis, the influence of different components of a porous medium is quantified and conclusions concerning the characteristic key-figures are drawn.
info:eu-repo/classification/ddc/620, Grundwasserleiter, Wasserströmung, Mehrstoffsystem, Sensitivitätsanalyse, Tracerkinetik, Numerisches Modell, Ingenieurwissenschaften, Grundwassermodellierung, Mehrkontinuum Modell, Charakterisierung, Durchbruchskurve, groundwater modeling, multi continuum approach, sensitivity analysis, tracer breakthrough curve, characterization
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