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| Titel |
Large zero-tension plate lysimeters for soil water and solute collection in undisturbed soils |
| VerfasserIn |
A. Peters, W. Durner |
| 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 ; 13, no. 9 ; Nr. 13, no. 9 (2009-09-18), S.1671-1683 |
| Datensatznummer |
250011997
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| Publikation (Nr.) |
 copernicus.org/hess-13-1671-2009.pdf |
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| Zusammenfassung |
| Water collection from undisturbed unsaturated soils to estimate in situ water
and solute fluxes in the field is a challenge, in particular if soils are
heterogeneous. Large sampling devices are required if preferential flow paths
are present. We present a modular plate system that allows installation of
large zero-tension lysimeter plates under undisturbed soils in the field. To
investigate the influence of the lysimeter on the water flow field in the
soil, a numerical 2-D simulation study was conducted for homogeneous soils
with uni- and bimodal pore-size distributions and stochastic Miller-Miller
heterogeneity. The collection efficiency was found to be highly dependent on
the hydraulic functions, infiltration rate, and lysimeter size, and was
furthermore affected by the degree of heterogeneity. In homogeneous soils
with high saturated conductivities the devices perform poorly and even large
lysimeters (width 250 cm) can be bypassed by the soil water. Heterogeneities
of soil hydraulic properties result into a network of flow channels that
enhance the sampling efficiency of the lysimeter plates. Solute breakthrough
into zero-tension lysimeter occurs slightly retarded as compared to the free
soil, but concentrations in the collected water are similar to the mean flux
concentration in the undisturbed soil. To validate the results from the
numerical study, a dual tracer study with seven lysimeters of 1.25×1.25 m
area was conducted in the field. Three lysimeters were installed underneath a
1.2 m filling of contaminated silty sand, the others deeper in the
undisturbed soil. The lysimeters directly underneath the filled soil material
collected water with a collection efficiency of 45%. The deeper lysimeters
did not collect any water. The arrival of the tracers showed that almost all
collected water came from preferential flow paths. |
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