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In Deserts, Which Dunes Are the Most Stable ?

ScienceDaily (May 28, 2010)

In Deserts, Which Dunes Are the Most Stable ?

ScienceDaily (May 28, 2010)

By modeling a desert where the wind blows in two directions, researchers from CNRS and Université Paris Diderot-Paris7 have succeeded in observing and highlighting, for the very first time, the formation process and long-term evolution of two types of very large sand dunes : transverse dunes and longitudinal dunes. They have demonstrated that longitudinal dunes and barchans — croissant-shaped dunes formed in a unidirectional wind regime — are the most stable over time. Their results should provide a better understanding of how dunes and deserts evolve on Earth and also help to deduce important information concerning wind regimes on Titan or Mars, for example.

To study the formation and the stability of sand dunes, Stéphane Douady’s team at the Laboratoire de Matière et Systèmes Complexes (CNRS / Université Paris Diderot-Paris7) has designed an ingenious device that reproduces, in miniature scale in the laboratory, the much larger dunes found in deserts. Their experimental model is made of glass beads set in motion by water in the same way as grains of sand are moved by winds. The advantages are that the resulting dunes formed of glass beads are small (a few centimeters) and build up rapidly under water. The resulting shapes are similar to wind-generated dunes, which has enabled researchers to study in detail the mechanisms involved in their formation.

Pour en savoir plus (ScienceDaily)

Page publiée le 19 novembre 2011, mise à jour le 4 août 2014