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| Titel |
Using measured soil water contents to estimate evapotranspiration and root water uptake profiles – a comparative study |
| VerfasserIn |
M. Guderle, A. Hildebrandt |
| 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 ; 19, no. 1 ; Nr. 19, no. 1 (2015-01-21), S.409-425 |
| Datensatznummer |
250120600
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| Publikation (Nr.) |
 copernicus.org/hess-19-409-2015.pdf |
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| Zusammenfassung |
| Understanding the role of plants in soil water relations, and thus
ecosystem functioning, requires information about root water uptake. We
evaluated four different complex water balance methods to estimate sink term
patterns and evapotranspiration directly from soil moisture measurements. We
tested four methods. The first two take the difference between two
measurement intervals as evapotranspiration, thus neglecting vertical flow.
The third uses regression on the soil water content time series and
differences between day and night to account for vertical flow. The fourth
accounts for vertical flow using a numerical model and iteratively solves
for the sink term. None of these methods requires any a priori
information of root distribution parameters or evapotranspiration, which is
an advantage compared to common root water uptake models. To test the
methods, a synthetic experiment with numerical simulations for a grassland
ecosystem was conducted. Additionally, the time series were perturbed to
simulate common sensor errors, like those due to measurement precision and
inaccurate sensor calibration. We tested each method for a range of
measurement frequencies and applied performance criteria to evaluate the
suitability of each method. In general, we show that methods accounting for
vertical flow predict evapotranspiration and the sink term distribution more
accurately than the simpler approaches. Under consideration of possible
measurement uncertainties, the method based on regression and
differentiating between day and night cycles leads to the best and most
robust estimation of sink term patterns. It is thus an alternative to more
complex inverse numerical methods. This study demonstrates that highly
resolved (temporally and spatially) soil water content measurements may be used
to estimate the sink term profiles when the appropriate approach is used. |
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