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| Titel |
Transition to saturation in a gradually layered soil: effect of the hydraulic conductivity decrease with depth |
| VerfasserIn |
M. Peli, S. Barontini, R. Ranzi |
| 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 |
250068723
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| Zusammenfassung |
| The soil hydraulic conductivity at saturation Ks typically decreases with depth across the
upper soil layers, thus strongly characterising the water partitioning and playing an important
role in the groundwater recharge. Peaks of water content and perched waters can in fact take
place even if the porosity and the soil–water retention relationship are homogeneous, and if
the soil lies on a capillary barrier.
Aiming at better understanding these processes, a one dimensional infiltration at constant
rate, into a finite depth gradually layered soil, was numerically investigated by means of
Hydrus1D and compared with theoretical approaches. Ks was assumed to exponentially
decrease with depth and the soil to be saturated at the bottom. After a preliminar dimensional
analysis on the basis of the Buckigham Ï–theorem, two sets of simulations were performed,
in order to investigate a strongly Ks–decreasing soil and a more homogeneous
one.
According to an analytical solution of the Richards equation, peaks of water content onset
at the soil surface and they are enveloped as the maximum water content moves downward.
Then either the saturation is reached within the soil, thus leading to a perched water table
which rapidly reaches steady conditions, or the peak vanishes. In this case, depending on the
infiltration rate, a perched water can anyway onset growing from the bottom of the domain, or
the solution can recover its monotonicity allowing a water flow to take place in the direction
of the increasing water content. The infiltration rate at which the soil is lead to waterlogging
depends on the whole Ks profile and it is therefore less than the Ks of the upper soil
layer. |
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