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| Titel |
Comparison of three stream tube models predicting field-scale solute transport |
| VerfasserIn |
D. Jacques, J. Vanderborght, D. Mallants, D.-J. Kim, H. Vereecken, J. Feyen |
| 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 ; 1, no. 4 ; Nr. 1, no. 4, S.873-893 |
| Datensatznummer |
250000241
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| Publikation (Nr.) |
 copernicus.org/hess-1-873-1997.pdf |
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| Zusammenfassung |
| In this paper the relation between local- and field-scale
solute transport parameters in an unsaturated soil profile is investigated. At two experimental sites,
local-scale steady-state solute transport was measured in-situ using 120
horizontally installed TDR probes at 5 depths. Local-scale solute transport
parameters determined from BTCs were used to predict field-scale solute
transport using stochastic stream tube models (STM). Local-scale solute
transport was described by two transport models: (1) the convection-dispersion
transport model (CDE), and (2) the stochastic convective lognormat transfer
model (CLT). The parameters of the CDE-model were found to be lognormally
distributed, whereas the parameters of the CLT model were normally distributed.
Local-scale solute transport heterogeneity within the measurement volume
of a TDR-probe was an important factor causing field-scale solute dispersion.
The study of the horizontal scale-dependency revealed that the variability
in the solute transport parameters contributes more to the field-scale
dispersion at deeper depths than at depths near the surface. Three STMs
were used to upscale the local transport parameters: (i) the stochastic
piston flow STM-I assuming local piston flow transport, (ii) the convective-dispersive
STM-II assuming local CDE transport, and (iii) the stochastic convective lognormal
STM-III assuming local CLT. The STM-I considerably underpredicted the field-scale
solute dispersion indicating that local-scale dispersion processes, which
are captured within the measurement volume of the TDR-probe, are important
to predict field-scale solute transport. STM-II and STM-III both described
the field-scale breakthrough curves (BTC) accurately if depth dependent
parameters were used. In addition, a reasonable description of the horizontal
variance of the local BTCs was found. STM-III was (more) superior to STM-II
if only one set of parameters from one depth is used to predict the field-scale
solute BTCs at several depths. This indicates that the local-scale solute
transport process, as measured with TDR in this study, is in agreement
with the CLT-hypothesis. |
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