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| Titel |
On the reliability of analytical models to predict solute transport in a fracture network |
| VerfasserIn |
C. Cherubini, C. I. Giasi, N. Pastore |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1027-5606
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| Digitales Dokument |
URL |
| Erschienen |
In: Hydrology and Earth System Sciences ; 18, no. 6 ; Nr. 18, no. 6 (2014-06-24), S.2359-2374 |
| Datensatznummer |
250120394
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| Publikation (Nr.) |
 copernicus.org/hess-18-2359-2014.pdf |
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| Zusammenfassung |
In hydrogeology, the application of reliable tracer transport model
approaches is a key issue to derive the hydrodynamic properties of aquifers.
Laboratory- and field-scale tracer dispersion breakthrough curves (BTC) in
fractured media are notorious for exhibiting early time arrivals and
late time tailing that are not captured by the classical
advection–dispersion equation (ADE). These "non-Fickian" features are
proven to be better explained by a mobile–immobile (MIM) approach. In this
conceptualization the fractured rock system is schematized as a continuous
medium in which the liquid phase is separated into flowing and stagnant
regions.
The present study compares the performances and reliabilities of the
classical MIM and the explicit network model
(ENM), taking expressly into account the network geometry for describing
tracer transport behavior in a fractured sample at bench scale. Though ENM
shows better fitting results than MIM, the latter remains still valid as it
proves to describe the observed curves quite well.
The results show that the presence of nonlinear flow plays an important role
in the behavior of solute transport. First, the distribution of solute
according to different pathways is not constant, but it is related to the flow
rate. Second, nonlinear flow influences advection in that it leads to a
delay in solute transport respect to the linear flow assumption. However,
nonlinear flow is not shown to be related with dispersion. The experimental
results show that in the study case the geometrical dispersion dominates the
Taylor dispersion. However, the interpretation with the ENM shows a weak
transitional regime from geometrical dispersion to Taylor dispersion for high
flow rates. Incorporating the description of the flow paths in the analytical
modeling has proven to better fit the curves and to give a more robust
interpretation of the solute transport. |
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