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| Titel |
Thermal imaging of water repellence breakdown and build up following
surfactant application |
| VerfasserIn |
Abdulkareem Alsih, Matthias Leopold, Gavan McGrath |
| Konferenz |
EGU General Assembly 2017
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| Medientyp |
Artikel
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| Sprache |
en
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 19 (2017) |
| Datensatznummer |
250142250
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| Publikation (Nr.) |
 EGU/EGU2017-5848.pdf |
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| Zusammenfassung |
| Surfactants are used in dry land cropping systems to improve water infiltration in water
repellent soils, yet the dynamic nature of water repellence during various seasons and the
associated hydrologic changes are still poorly understood. Here we evaluate surface
temperature changes of a water repellent sand in response to irrigation and surfactant
applications, reflecting infiltration, evaporation, and energy balance changes across
multiple wetting-drying cycles. Using a near-infrared thermal camera soil surface
temperatures of 15 1m2 plots were recorded at 10 minute intervals for three weeks. Plots
differed by the width of surfactant application bands ( 16 cm, 25 cm, 50 cm, and
100 cm wide surfactant bands as well as a control with no surfactant), individual
treatments were replicated three times. Temporal changes in the spatial variability
was examined using semivariograms and wavelets. The semivariogram analysis
indicates that in contrast to the thinnest surfactant bands, wide bands lead to a gradual
increase in soil-temperature heterogeneity towards that seen in a control. Wavelets and
time-distance plots reveal a non-linear switch in soil temperature dynamics for
surfactant treated plots which were absent in 100 cm band and control plots. This
switch, evident in the relative temperature differences across the plot during diurnal
cycling, was associated with a gradual drop in ambient temperatures. These results
image water repellence breakdown in the field. The study demonstrates the general
suitability of using thermal surface properties of water repellent soils to investigate the
dynamics of water repellence breakdown. This knowledge can be used to test the
efficiency of available and new surfactant products to overcome water repellency. |
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