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| Titel |
Averaged water potentials in soil water and groundwater, and their connection to menisci in soil pores, field-scale flow phenomena, and simple groundwater flows |
| VerfasserIn |
G. H. Rooij |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1027-5606
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| Digitales Dokument |
URL |
| Erschienen |
In: Hydrology and Earth System Sciences ; 15, no. 5 ; Nr. 15, no. 5 (2011-05-26), S.1601-1614 |
| Datensatznummer |
250012791
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| Publikation (Nr.) |
 copernicus.org/hess-15-1601-2011.pdf |
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| Zusammenfassung |
| The movement of subsurface water is mostly studied at the pore scale and the
Darcian scale, but the field and regional scales are of much larger societal
interest. Volume-averaging has provided equations at these larger scales,
but the required restrictions rendered them of little practical interest.
Others hypothesized a direct connection at hydrostatic equilibrium between
the average matric potential of a subsurface body of water and the average
pressure drop over the menisci in the soil pores. The link between the
volume-averaged potential energy of subsurface water bodies and large-scale
fluxes remains largely unexplored. This paper treats the effect of menisci
on the potential energy of the water behind them in some detail, and
discusses some field-scale effects of pore-scale processes. Then, various
published expressions for volume-averaged subsurface water potentials are
compared. The intrinsic phase average is deemed the best choice. The
hypothesized relationship between average matric potential and average
meniscus curvature is found to be valid for unit gradient flow instead of
hydrostatic equilibrium. Still, this restriction makes the relationship hold
only for a specific depth range in the unsaturated zone under specific
conditions, and certainly not for entire fields or catchments. In the
groundwater, volume-averaged potential energy is of more use: for
linearized, steady flows with flow lines that are parallel, radially
diverging, and radially converging, proofs are derived for proportionality
between averaged hydraulic potentials and fluxes towards open water at a
fixed potential. For parallel flow, a simplified but relevant transient flow
case also exhibits this proportionality. |
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