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| Titel |
Estimating hydraulic conductivity of internal drainage for layered soils in situ |
| VerfasserIn |
S. S. W. Mavimbela, L. D. Rensburg |
| 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 ; 17, no. 11 ; Nr. 17, no. 11 (2013-11-04), S.4349-4366 |
| Datensatznummer |
250085983
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| Publikation (Nr.) |
 copernicus.org/hess-17-4349-2013.pdf |
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| Zusammenfassung |
| The soil hydraulic conductivity (K function) of three layered soils
cultivated at Paradys Experimental Farm, near Bloemfontein (South Africa),
was determined from in situ drainage experiments and analytical models.
Pre-ponded monoliths, isolated from weather and lateral drainage, were
prepared in triplicate on representative sites of the Tukulu, Sepane and
Swartland soil forms. The first two soils are also referred to as Cutanic
Luvisols and the third as Cutanic Cambisol. Soil water content (SWC) was
measured during a 1200 h drainage experiment. In addition soil physical
and textural data as well as saturated hydraulic conductivity (Ks) were
derived. Undisturbed soil core samples of 105 mm with a height of 77 mm from
soil horizons were used to measure soil water retention curves (SWRCs).
Parameterization of SWRC was through the Brooks and Corey model. Kosugi and van
Genuchten models were used to determine SWRC parameters and fitted with a RMSE
of less 2%. The SWRC was also used to estimate matric suctions for in
situ drainage SWC following observations that laboratory and in situ SWRCs
were similar at near saturation. In situ K function for horizons and the
equivalent homogeneous profiles were determined. Model predictions based on
SWRC overestimated horizons K function by more than three orders of
magnitude. The van Genuchten–Mualem model was an exception for certain soil
horizons. Overestimates were reduced by one or more orders of magnitude when
inverse parameter estimation was applied directly to drainage SWC with
HYDRUS-1D code. Best fits (R2 ≥ 0.90) were from Brooks and Corey,
and van Genuchten–Mualem models. The latter also predicted the profiles'
effective K function for the three soils, and the in situ based function was
fitted with R2 ≥ 0.98 irrespective of soil type. It was concluded
that the inverse parameter estimation with HYDRUS-1D improved models' K
function estimates for the studied layered soils. |
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