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| Titel |
Evolution of karst conduit networks in transition from pressurized flow to free-surface flow |
| VerfasserIn |
M. Perne, M. Covington, F. Gabrovsek |
| 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 ; 18, no. 11 ; Nr. 18, no. 11 (2014-11-24), S.4617-4633 |
| Datensatznummer |
250120531
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| Publikation (Nr.) |
 copernicus.org/hess-18-4617-2014.pdf |
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| Zusammenfassung |
| Most of the existing models of speleogenesis are limited to situations where
flow in all conduits is pressurized. The feedback between the distribution
of hydraulic head and growth of new solution conduits determines the
geometry of the resulting conduit network. We present a novel modeling
approach that allows a transition from pressurized (pipe) flow to a free-surface (open-channel) flow in evolving discrete conduit networks. It
calculates flow, solute transport and dissolution enlargement within each
time step and steps through time until a stable flow pattern is established.
The flow in each time step is calculated by calling the US Environmental Protection Agency Storm Water
Management Model (US Environmental Protection Agency, 2014), which efficiently solves the 1-D Saint-Venant
equations in a network of conduits. Two basic scenarios are modeled, a
low-dip scenario and a high-dip scenario. In the low-dip scenario a slightly
inclined plane is populated with a rectangular grid of solution conduits.
The recharge is distributed to randomly selected junctions. The results for
the pressurized flow regime resemble those of the existing models. When the
network becomes vadose, a stable flow pathway develops along a system of
conduits that occupy the lowest positions at their inlet junctions. This
depends on the initial diameter and inlet position of a conduit, its total
incision in a pressurized regime and its alignment relative to the dip of
the plane, which plays important role during the vadose entrenchment. In the
high-dip scenario a sub-vertical network with recharge on the top and
outflow on the side is modeled. It is used to demonstrate the vertical
development of karst due to drawdown of the water table, development of
invasion vadose caves during vadose flow diversion and to demonstrate the
potential importance of deeply penetrating conductive structures. |
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