Formation and reorganization timescales of aeolian landscapes

Andrew Gunn 

Landscapes created through sediment transport are shaped by the interaction of flow and form. In landscapes where wind is the agent of geomorphic work, this is clear at the small-scale; equilibrium dune morphology is linked to the wind climate and the supply of sediment. At larger scales, this linkage becomes ambiguous because the form of giant dunes and dune fields integrate long histories of varied wind and sand supply. Without a framework to assess aeolian landscape evolution at this scale, the time taken to form and reorganize dune fields has been largely unexplored quantitatively. We show that these timescales can be understood by linking modern wind and topographic datasets for one of the most expansive and morphologically diverse unvegetated dune fields, the Rub’ al Khali. By linking sediment flux to the surface area and slope of dunes, and growth to the divergence in that flux, we fully couple form and flow at the dune field-scale. Our results show quantitatively how dune field formation and reorganization are outpaced by climate change and the implications for stratigraphic interpretation.