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Summary: Why Do Active and Stabilized Dunes Coexist under the Same Climatic Conditions?
Hezi Yizhaq,1
Yosef Ashkenazy,1
and Haim Tsoar2
1
Department of Solar Energy and Environmental Physics, Blaustein Institutes for Desert Research,
Ben-Gurion University of the Negev, Sede Boqer Campus 84990 Israel
2
Department of Geography and Environmental Development Ben-Gurion University of the Negev, Beer-Sheva 84105, Israel
(Received 4 November 2006; revised manuscript received 13 February 2007; published 2 May 2007)
Sand dunes can be active (mobile) or stable, mainly as a function of vegetation cover and wind power.
However, there exists as yet unexplained evidence for the coexistence of bare mobile dunes and vegetated
stabilized dunes under the same climatic conditions. We propose a model for dune vegetation cover driven
by wind power that exhibits bistabilty and hysteresis with respect to the wind power. For intermediate
wind power, mobile and stabilized dunes can coexist, whereas for low (or high) wind power they can be
fixed (or mobile). Climatic change or human intervention can turn active dunes into stable ones and vice
versa; our model predicts that prolonged droughts with stronger winds can result in dune reactivation.
DOI: 10.1103/PhysRevLett.98.188001 PACS numbers: 45.70.ÿn, 05.45.ÿa
Sand dunes form an important, unique, and complex
ecological [1] and physical [2] system. Approximately
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