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Barchan‐parabolic dune pattern transition from vegetation stability threshold
Author(s) -
Reitz Meredith D.,
Jerolmack Douglas J.,
Ewing Ryan C.,
Martin Raleigh L.
Publication year - 2010
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2010gl044957
Subject(s) - aeolian processes , geology , vegetation (pathology) , curvature , inversion (geology) , crest , geomorphology , deposition (geology) , atmospheric sciences , sediment , geometry , medicine , physics , mathematics , pathology , structural basin , quantum mechanics
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.