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| Titel |
Dynamics of an unconfined aquifer |
| VerfasserIn |
Adrien Guérin, Olivier Devauchelle, Eric Lajeunesse, François Métivier |
| Konferenz |
EGU General Assembly 2014
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 16 (2014) |
| Datensatznummer |
250097104
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| Publikation (Nr.) |
 EGU/EGU2014-12652.pdf |
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| Zusammenfassung |
| Most rainwater infiltrates into the ground, where it flows towards a stream slowly within the
aquifer. However, the stream discharge increases rapidly during a rain event, and decreases
slowly during droughts.
To reconcile these observations, we use a thin tank filled with glass beads to
simulate this process in a simplified laboratory experiment. A drilled pipe located
above the tank reproduces a homogeneous rain, which infiltrates into the porous
medium. Groundwater exits the aquifer through one side of the tank. The resulting
hydrograph resembles field measurements: the discharge increases quickly, and decays
slowly.
A theory based on Darcy’s law and the shallow-water (or Dupuit-Boussinesq)
approximation, reveals two asymptotic regimes. At the beginning of a rain event, the river
discharge increases linearly with time, with a slope proportional to the rainfall rate to the
power of 3-2. Long after the rain has stopped it decreases as 1-t2, as predicted by
Polubarinova-Kochina (1962). These predictions compare well against our experimental data. |
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