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| Titel |
Laws of valley growth |
| VerfasserIn |
Robert Yi, Hansjoerg Seybold, Daniel Rothman |
| 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 |
250100860
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| Publikation (Nr.) |
 EGU/EGU2014-16864.pdf |
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| Zusammenfassung |
| River networks incised by re-emerging groundwater flow provide a model framework for
studying channelization. The underlying physical equations are well-defined and thus
analytical predictions can be obtained and tested in the field. Theory of growth in such
channel systems was first formed by Dunne in the early 1980s. A small bulge in the
sidewall of a stream leads to the focusing of the ground water flow, and thus to
a larger flux of water resulting in a higher erosion rate in this direction. In time
such small perturbations grow into newly formed channels, but how they do so is
unclear.
To probe this problem, we begin by relating the advancement of the tip to the discharge
into the spring. If a stream advances at a rate v ~ qη, where q is the discharge of water into
the tip, theory of growth in a diffusive field predicts that η has to be smaller than 1 to obtain
ramified networks. We test this hypothesis by measuring erosion rates in a field site of
groundwater driven channels on the Florida Panhandle. Our network reconstruction yields tip
growth rates, which we can directly compare to observational rates obtained from collected
cosmogenic 10Be data. This allows us to both verify the existence of a discharge-erosion
relation, as well as better characterize growth and competition in the channelization
process. |
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