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| Titel |
Plot and field scale soil moisture dynamics and subsurface wetness control on runoff generation in a headwater in the Ore Mountains |
| VerfasserIn |
E. Zehe, T. Graeff, M. Morgner, Andreas Bauer, A. Bronstert |
| 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 ; 14, no. 6 ; Nr. 14, no. 6 (2010-06-01), S.873-889 |
| Datensatznummer |
250012329
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| Publikation (Nr.) |
 copernicus.org/hess-14-873-2010.pdf |
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| Zusammenfassung |
| This study presents an application of an innovative
sampling strategy to assess soil moisture dynamics in a headwater of the
Weißeritz in the German eastern Ore Mountains. A grassland site and a
forested site were instrumented with two Spatial TDR clusters (STDR) that
consist of 39 and 32 coated TDR probes of 60 cm length. Distributed time
series of vertically averaged soil moisture data from both sites/ensembles
were analyzed by statistical and geostatistical methods. Spatial variability
and the spatial mean at the forested site were larger than at the grassland
site. Furthermore, clustering of TDR probes in combination with long-term monitoring
allowed identification of average spatial covariance
structures at the small field scale for different wetness states. The correlation
length of soil water content as well as the sill to nugget
ratio at the grassland site increased with increasing average wetness and
but, in contrast, were constant at the forested site. As soil properties at
both the forested and grassland sites are extremely variable, this suggests
that the correlation structure at the forested site is dominated by the
pattern of throughfall and interception. We also found a very strong
correlation between antecedent soil moisture at the forested site and runoff
coefficients of rainfall-runoff events observed at gauge Rehefeld.
Antecedent soil moisture at the forest site explains 92% of the
variability in the runoff coefficients. By combining these results with a
recession analysis we derived a first conceptual model of the dominant
runoff mechanisms operating in this catchment. Finally, we employed a
physically based hydrological model to shed light on the controls of soil-
and plant morphological parameters on soil average soil moisture at the
forested site and the grassland site, respectively. A homogeneous soil setup
allowed, after fine tuning of plant morphological parameters, most of the
time unbiased predictions of the observed average soil conditions observed
at both field sites. We conclude that the proposed sampling strategy of
clustering TDR probes is suitable to assess unbiased average soil moisture
dynamics in critical functional units, in this case the forested site, which is a
much better predictor for event scale runoff formation than pre-event discharge.
Long term monitoring of such critical landscape elements could
maybe yield valuable information for flood warning in headwaters. We thus
think that STDR provides a good intersect of the advantages of permanent
sampling and spatially highly resolved soil moisture sampling using mobile
rods. |
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