Complementary classifications of aeolian dunes based on morphology, dynamics, and fluid mechanics

This is a Preprint and has not been peer reviewed. The published version of this Preprint is available: https://doi.org/10.1016/j.earscirev.2024.104772. This is version 3 of this Preprint.

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Authors

Sylvain Courrech du Pont , David Michael Rubin, Clément Narteau, Mathieu Gaëtan André Lapôtre, Mackenzie Day, Philippe Claudin, Ian Livingstone, Matt W Telfer, Jani Radebaugh, Cyril Gadal, Andrew Gunn , Patrick A. Hesp, Sabrina Carpy, Charles S Bristow, Andreas C. W. Baas, Ryan C. Ewing, Giles Frederick Salisbury Wiggs

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.

DOI

https://doi.org/10.31223/X5M09D

Subjects

Earth Sciences, Fluid Dynamics, Geomorphology, Other Earth Sciences, Physical Sciences and Mathematics, Physics, Planetary Geomorphology, Planetary Sciences, Sedimentology

Keywords

Dune Classification; Geomorphology; Morphodynamics; Fluid Mechanics; Sediment Transport; Aeolian Bedforms; Desert, Coastal and Planetary Dune TypesWind-blown Landscapes, Dune Classification, geomorphology, Morphodynamics, Fluid Mechanics, sediment transport, Aeolian Bedforms, Desert, Coastal and Planetary Dune Types, Wind-blown Landscapes

Dates

Published: 2023-10-03 09:46

Last Updated: 2024-05-14 00:28

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License

CC-BY Attribution-NonCommercial-ShareAlike 4.0 International