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| Titel |
The dominant role of structure for solute transport in soil: experimental evidence and modelling of structure and transport in a field experiment |
| VerfasserIn |
H.-J. Vogel, I. Cousin, O. Ippisch, P. Bastian |
| 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 ; 10, no. 4 ; Nr. 10, no. 4 (2006-07-07), S.495-506 |
| Datensatznummer |
250008137
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| Publikation (Nr.) |
 copernicus.org/hess-10-495-2006.pdf |
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| Zusammenfassung |
| A classical transport experiment was performed in a field plot of 2.5 m2
using the dye tracer brilliant blue. The measured tracer distribution
demonstrates the dominant role of the heterogeneous soil structure for solute
transport. As with many other published experiments, this evidences the need
of considering the macroscopic structure of soil to predict flow and
transport.
We combine three different approaches to represent the relevant structure of
the specific situation of our experiment: i) direct measurement, ii)
statistical description of heterogeneities and iii) a conceptual model of
structure formation. The structure of soil layers was directly obtained from
serial sections in the field. The sub-scale heterogeneity within the soil
horizons was modelled through correlated random fields with estimated
correlation lengths and anisotropy. Earthworm burrows played a dominant role
at the transition between the upper soil horizon and the subsoil. A model
based on percolation theory is introduced that mimics the geometry of
earthworm burrow systems.
The hydraulic material properties of the different structural units were
obtained by direct measurements where available and by a best estimate
otherwise. From the hydraulic structure, the 3-dimensional velocity field of
water was calculated by solving Richards' Equation and solute transport was
simulated. The simulated tracer distribution compares reasonably well with
the experimental data. We conclude that a rough representation of the
structure and a rough representation of the hydraulic properties might be
sufficient to predict flow and transport, but both elements are definitely
required. |
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