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Abstract

Dunes form where winds blow over a bed of mobile sediment grains — conditions that are common in our solar system. On Earth, dunes abound in arid continental interiors and along sandy coastlines. Dune fields have also been recognized on Venus, Mars, Saturn’s moon Titan, and Pluto. In response to the different boundary conditions and other environmental forcings, dunes adopt a rich diversity of shapes, sizes, and behaviors. Thus, people around the globe and over centuries have developed a rich vocabulary to describe dunes and their complexity. As a result, existing dune nomenclature often includes redundant terms with differing definitions across scientific communities. Previous studies have endeavored to link dune shape to environmental forcing, usually by means of correlation. Although instructive, correlation-based classifications can be misleading if not based on underlying mechanics or if dune morphogenetic classes are not uniquely defined. Here, we synthesize existing dune terminology and use the last two decades of research on dune morphodynamics to propose three complementary dune classification schemes based on: (1) descriptive dune geomorphology, (2) morphodynamic processes, and (3) fluid mechanics and physics of sediment transport. The first classification relates dune types to geomorphic setting, the presence or absence of vegetation or obstacles, and dune shape (including planform shape, and cross-sectional symmetry or asymmetry). Dune classes can be further subdivided where the direction of sand transport is known independently. The second classification relates dune types and shapes to bed properties (sand-covered vs partially starved bed) and wind forcing (directional variability or the relative strengths and directions of wind modes) that together influence dune dynamics (growth, migration, elongation) and select the dominant processes by which dunes are shaped and oriented relative to the resultant transport direction. The third classification relates, for different planetary environments, the range of possible dune sizes, from minimum to maximum wavelength, to fluid flow regime (rough or smooth) and the response of sediment flux, which influence the coupling between sand bed topography, fluid flow, and sediment transport. These characteristic lengths are useful scales for comparative geomorphology. The three classification schemes provide complementary information. Together, they form a unified framework for geomorphologists, sedimentologists, geographers, physicists, and others to describe windblown sand dunes on Earth and beyond through their shape, dynamics, and size as a response to winds and boundary conditions.

Publication Date

2024-08-01

Publication Title

Earth-Science Reviews

Volume

255

ISSN

0012-8252

Acceptance Date

2024-06-24

Deposit Date

2024-08-06

Funding

This work began during a funded workshop at the Fondation des Treilles (www.les-treilles.com), a wonderful place in the south of France for scientific exchange, creativity, and reflection. The authors are grateful to their collaborators who have contributed to the work reviewed in this paper over the years. SCdP and CN would like to thank St\u00E9phane Douady, Xin Gao, Mathieu G\u00E9nois, Ping L\u00FC, Antoine Lucas, Erwan Reffet, S\u00E9bastien Rodriguez, Olivier Rozier, and Deguo Zhang. PC would like to thank Bruno Andreotti, Fran\u00E7ois Charru, Orencio Dur\u00E1n, Pan Jia, and Michel Louge. DR acknowledges Ralph Hunter for discussions on the topics in this paper, beginning 40 years ago. Na\u00EFs Coq (plectoneme@proton.me) did the graphic design of classification figures. We thank editors Timothy James Horscroft and Christopher Fielding, and two anonymous reviewers, whose comments improved our manuscript. AG acknowledges funding from the Australian Research Council through grant #DE240100552. CN acknowledges funding from Initiative d'Excellence Universit\u00E9 Paris Cit\u00E9 through grant ANR-18-IDEX-0001, and the French National Research Agency through grant ANR-23-CE56-0008. This work began during a funded workshop at the Fondation des Treilles ( www.les-treilles.com ), a wonderful place in the south of France for scientific exchange, creativity and reflection. The authors are grateful to their collaborators who have contributed to the work reviewed in this paper over the years. SCdP and CN would like to thank St\u00E9phane Douady, Xin Gao, Mathieu G\u00E9nois, Ping L\u00FC, Antoine Lucas, Erwan Reffet, S\u00E9bastien Rodriguez and Olivier Rozier. PC would like to thank Bruno Andreotti, Fran\u00E7ois Charru, Orencio Dur\u00E1n, Pan Jia and Michel Louge. DR acknowledges Ralph Hunter for discussions on the topics in this paper, beginning 40\u202Fyears ago. Na\u00EFs Coq ( plectoneme@proton.me ) did the graphic design of classification figures. We thank editors Timothy James Horscroft and Christopher Fielding, and two anonymous reviewers, whose comments improved our manuscript. AG acknowledges funding from the Australian Research Council through grant # DE240100552 . CM acknowledges funding from Initiative d'Excellence Universit\u00E9 Paris Cit\u00E9 through grant ANR-18-IDEX-0001 , and the French National Research Agency through grant ANR-23-CE56-0008 .

Keywords

Dune classification, Geomorphology, Morphodynamics, Fluid mechanics, Sediment transport, Aeolian bedforms, Desert, coastal, and planetary dune types, Wind-blown landscapes

Creative Commons License

Creative Commons Attribution-NonCommercial 4.0 International License
This work is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License

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