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| Titel |
Two independent dune growth mechanisms: from laboratory to landscape-scale experiments |
| VerfasserIn |
Clement Narteau, Lv Ping, Sylvain Courrech du Pont, Zhibao Dong, Laura Cascales-Fernandez, Sebastien Rodriguez |
| 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 |
250105188
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| Publikation (Nr.) |
 EGU/EGU2015-4643.pdf |
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| Zusammenfassung |
| Using laboratory subaqueous experiments, we show that a single bidirectional flow regime
can lead to two different dune orientations depending on sediment availability. The erodibility
of the bed selects the overriding mechanism for the formation of dunes. Then, dunes may
either (1) increase in height from the destabilization of a sand bed with no restriction in
sediment availability or (2) grow by extension away from a localized sand source in zones of
low sand availability.
These results are used to develop a new set of landscape-scale experiments in the
Tengger desert (Inner Mongolia, China). Exposed to bimodal winds, this site is
unique because it allows multiparametric analysis of dune morphodynamics in
a natural environment (16 hectares) under well-controlled initial and boundary
conditions. The orientation of dunes as a function of the wind regime and the coupling
between flow and topography are currently investigated in three experiments that
provide empirical support for the coexistence of two independent dune growth
mechanisms.
In both laboratory and landscape scale experiments, we find that dunes that are
transport-limited select an orientation that maximizes the normal to crest components of
transport. In zones of limited sand supply, dunes elongate in the direction of the resultant
sand flux at the crest. We show how these results can be used to quantitatively predicts the
orientation of primary and secondary dune patterns in modern terrestrial sand seas but also on
Mars and Titan. |
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