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| Titel |
Estimation and spatialization of soil properties through infiltration experiments over the Kairouan plain (center of Tunisia) |
| VerfasserIn |
Marouen Shabou, Bernard Mougenot, Zohra Lili Chabaane, Gilles Boulet, Nadhira Ben Aissa, Mehrez Zribi |
| Konferenz |
EGU General Assembly 2013
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 15 (2013) |
| Datensatznummer |
250083414
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| Zusammenfassung |
| Studying soil hydrological processes requires the determination of soil hydraulic parameters
whose assessment using traditional methods is expensive and time-consuming. In this
paper, our objective is to estimate soil properties at local scale and then to spatialize
values across our study site (the Kairouan plain). It is situated in central Tunisia (9Ë
30’E-10Ë 15’E, 35Ë N, 35Ë 45’N). The climate in this region is semi-arid, with
an average annual rainfall of approximately 300 mm per year, Characterized by
a rainy season lasting from October to May, with the two rainiest months being
October and March. To overcome difficulties encountered by the classical models for
the characterization of hydraulic parameters, we have used the simple Beerkan
estimation of soil parameters method (BEST). It relies on the particle-size analysis, dry
bulk density and simple infiltration tests in cylinders. Furthermore, it facilitates the
determination of both the water retention curve, and the hydraulic conductivity curve,
defined by their shape and scale parameters. Shape parameters depend on soil texture
and derived from particle-size data. Scale parameters are derived from infiltration
experiments at null pressure head. Saturated water content is measured directly at the
end of infiltration. Hydraulic conductivity and water pressure scale parameters are
calculated from the steady-state infiltration rate and prior estimation of sorptivity
(S). This is obtained by fitting transient infiltration data on analytical models of
infiltration. The selected analytical model was compared with other infiltration
equations to estimate Sorptivity and hydraulic conductivity from infiltration modeling
data.
We derived from these experiments local pedotransfer functions to estimate hydraulic
conductivity, welting point and field capacity. These values will be assigned to the center of
the FAO textural classes.
Spatialization of soil hydrodynamic properties was based on the imprecise existing
textural soil map and with local texture modification by floods. The first step consists in
producing textural soil maps by merging soil units, identified from previous studies, and
typical profiles analysis. For complex soil units, remote sensing and auxiliary data was used
(geology, geomorphology, and digital elevation model). Furthermore, a large time series
Landsat TM images was used for mapping fields of bare soil based on color and
clay fraction indices. Validation over the selected fields was done by a spectral
radiometer. In addition, we will try to combine optical and radar remote sensing
data with the use of time series TERRASAR over a small region. This method
will allow the monitoring of the differential soil surface drying to invert textural
classes. A comparison with results obtained from Landsat TM imagery will be done. |
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