Barchan-parabolic dune pattern transition from vegetation stability threshold

Many dune fields exhibit a downwind transition from forward‐pointing barchan dunes to stabilized, backward‐pointing parabolic dunes, accompanied by an increase in vegetation. A recent model predicts this pattern transition occurs when dune surface erosion/deposition rates decrease below a threshold...

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Bibliographic Details
Published in:Geophysical research letters 2010-10, Vol.37 (19), p.n/a
Main Authors: Reitz, Meredith D., Jerolmack, Douglas J., Ewing, Ryan C., Martin, Raleigh L.
Format: Article
Language:English
Subjects:
aeolian
Atmospheric sciences
Climate change
Curvature
Dunes
Earth
Earth sciences
Earth, ocean, space
Environmental changes
Erosion rate
Erosion rates
Exact sciences and technology
Geophysics
Horns
Mathematical models
Nonlinear systems
parabolic dune
pattern transition
Phase transitions
threshold
Thresholds
Topographic surveys
Vegetation
vegetation feedback
Vegetation growth
Wind speed
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Summary:Many dune fields exhibit a downwind transition from forward‐pointing barchan dunes to stabilized, backward‐pointing parabolic dunes, accompanied by an increase in vegetation. A recent model predicts this pattern transition occurs when dune surface erosion/deposition rates decrease below a threshold of half the vegetation growth rate. We provide a direct test using a unique data set of repeat topographic surveys across White Sands Dune Field and find strong quantitative support for the model threshold. We also show the threshold hypothesis applied to a barchan dune results naturally in its curvature inversion, as the point of threshold crossing progresses from the horns to the crest. This simple, general threshold framework can be an extremely useful tool for predicting the response of dune landscapes to changes in wind speed, sediment supply, or vegetation growth rate. Near the threshold, a small environmental change could result in a drastic change in dune pattern and activity.
ISSN:0094-8276
1944-8007
DOI:10.1029/2010GL044957