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| Titel |
The Early Stages of Groundwater-fed River Bifurcation |
| VerfasserIn |
Robert Yi, Hansjoerg Seybold, Goodwin Gibbins, Daniel Rothman |
| Konferenz |
EGU General Assembly 2015
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 17 (2015) |
| Datensatznummer |
250101463
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| Publikation (Nr.) |
 EGU/EGU2015-611.pdf |
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| Zusammenfassung |
| Recent work shows, both theoretically and empirically, that river networks fed by subsurface
flow bifurcate on average at an angle of 2Ï/5 (Devauchelle et al. 2012). However, the
network’s existence within a complex natural framework obscures the emergence of this
pattern. Fortunately, this ambiguity betrays the presence of processes that have had
some effect on the channels during the network’s long history. In particular, we
concern ourselves with the signature of the third dimension | the topographic relief |
on the early stages of channel bifurcation. While, on average, channels grow in a
direction dictated by the shape of the groundwater table, we hypothesize that the
valley relief plays a crucial role in determining the opening angle and its relaxation
to 2Ï/5 in this regime. A network-wide averaging of several thousand channel
bifurcations driven by subsurface flow on the Florida panhandle reveals that rivers on
average branch initially at an angle wider than 2Ï/5, yet quickly relax to 2Ï/5 after
a few meters. We hypothesize that this initial wide growth direction is governed
by the shape of the topography. As these channels form independent valleys, the
Laplacian field exerts its dominance, yielding a persistent 2Ï/5 branching angle.
Our results therefore suggest that the path-selection of incipient channels fed by
subsurface flow is coupled both to the local topography and the surrounding groundwater
field. |
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