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| Titel |
What is the effect of local controls on the temporal stability of soil water contents? |
| VerfasserIn |
G. Martinez, Y. A. Pachepsky, H. Vereecken, K. Vanderlinden, H. Hardelauf, M. Herbst |
| Konferenz |
EGU General Assembly 2012
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 14 (2012) |
| Datensatznummer |
250063419
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| Zusammenfassung |
| Temporal stability of soil water content (TS SWC) reflects the spatio-temporal organization
of SWC. Factors and their interactions that control this organization, are not completely
understood and have not been quantified yet. It is understood that these factors should be
classified into groups of local and non-local controls. This work is a first attempt to
evaluate the effects of soil properties at a certain location as local controls Time series
of SWC were generated by running water flow simulations with the HYDRUS6
code. Bare and grassed sandy loam, loam and clay soils were represented by sets
of 100 independent soil columns. Within each set, values of saturated hydraulic
conductivity (Ks) were generated randomly assuming for the standard deviation of the
scaling factor of ln Ks a value ranging from 0.1 to 1.0. Weather conditions were
the same for all of the soil columns. SWC at depths of 0.05 and 0.60 m, and the
average water content of the top 1 m were analyzed. The temporal stability was
characterized by calculating the mean relative differences (MRD) of soil water
content.
MRD distributions from simulations, developed from the log-normal distribution of Ks,
agreed well with the experimental studies found in the literature. Generally, Ks was the
leading variable to define the MRD rank for a specific location. Higher MRD corresponded to
the lowest values of Ks when a single textural class was considered. Higher MRD were found
in the finer texture when mixtures of textural classes were considered and similar values of
Ks were compared. The relationships between the spread of the MRD distributions and the
scaling factor of ln Ks were nonlinear. Variation in MRD was higher in coarser textures
than in finer ones and more variability was seen in the topsoil than in the subsoil.
Established vegetation decreased variability of MRD in the root zone and increased
variability below. The dependence of MRD on Ks opens the possibility of using
SWC sensor networks to relate variations of MRD of measured SWC time series to
spatial variations of Ks. TS of SWC can provide information on Ks variability
at ungauged watersheds if the effect of non-local controls of SWC on TS is not
significant. Using the spatiotemporal statistics to convert the information about the
temporal variability of soil moisture into information about the spatial variability of
soil hydraulic properties presents an interesting avenue for further exploration. |
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