Development and steady states of transverse dunes: A numerical analysis of dune pattern coarsening and giant dunes

Gao, Xin; Narteau, C.; Rozier, Olivier

doi:10.1002/2015jf003549

Cited by 62 publications

(77 citation statements)

References 85 publications

(135 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Indeed, the aspect ratio of the reworked area decreases when the transport threshold increases. This is consistent with previous numerical results showing that barchan and transverse dunes flatten when the transport threshold increases (Gao et al, ; Zhang et al, ). The same conclusion can be drawn from a linear stability analysis.…”

Section: Stabilization and Shape Of An Elongating Linear Dunesupporting

confidence: 93%

Elongation and Stability of a Linear Dune

Rozier

Narteau

Gadal

et al. 2019

Geophysical Research Letters

Self Cite

View full text Add to dashboard Cite

Compared to barchan dunes, the morphodynamics of linear dunes that elongate on a nonerodible bed have barely been investigated by means of laboratory experiments or numerical simulations. Using a cellular automaton model, we study the elongation of a solitary linear dune from a sand source and show that it can reach a steady state. This steady state is analyzed to understand the physical processes at work along the dune. Crest reversals together with avalanche processes control the shape of transverse sections. Dune width and height decrease almost linearly with distance downstream until the minimum size for dune is reached. This is associated with a constant sand loss along the dune, which eventually compensates for the sediment influx and sets the dune length. This sand budget is discussed to distinguish an elongating linear dune from a barchan dune and to explain the complexity of linear dune fields in nature. Plain Language SummaryGiven the seasonal cycle, multidirectional wind regimes are highly prevalent in modern sand seas where linear dunes are the most frequent dune type. They vary in shape and size, but they are all characterized by linear ridges extending over long distances. Here we study the morphodynamics of linear dunes that elongate from a sand source under the action of reversing winds. We show that the sand loss increases with the length of the elongating linear dune which eventually converges to a steady state. We relate the dimensions and the shape of the dune at equilibrium to the sediment influx and the wind properties. The characterization of this elementary dune type is an essential step toward a better understanding of the interplay between winds and complex dune fields in nature. This is important for Earth in a context of climate change, but also for Mars and Titan, Saturn's largest moon, where direct wind measurements are not available to date.

show abstract

Section: Stabilization and Shape Of An Elongating Linear Dunesupporting

confidence: 93%

Elongation and Stability of a Linear Dune

Rozier

Narteau

Gadal

et al. 2019

Geophysical Research Letters

Self Cite

View full text Add to dashboard Cite

show abstract

“…Along with the wind regime, sediment supply has a critical control on dune morphodynamics [Gao et al, 2015[Gao et al, , 2016Rubin and Hunter, 1987;Ping et al, 2014;Courrech du Pont et al, 2014;Lucas et al, 2015]. Therefore, while we have very limited understanding of current and past wind conditions on Titan, our results showing a distinguishable physical properties between dunes and their inter-dunes have important implications in terms of dune morphodynamics as well as climatic conditions.…”

Section: Discussionmentioning

confidence: 80%

Texture and Composition of Titan's Equatorial Sand Seas Inferred From Cassini SAR Data: Implications for Aeolian Transport and Dune Morphodynamics

et al. 2019

View full text Add to dashboard Cite

Sand seas on Titan may reflect the present and past climatic conditions. Understanding the morphodynamics and physico-chemical properties of Titan's dunes is therefore essential for a better comprehension of the climatic and geological history of the largest Saturn's moon. We derived quantitatively surface properties (texture, composition) from the modelling of microwave backscattered signal and Monte-Carlo inversion of despeckled Cassini/SAR data over sand sea. We show that dunes and interdunes have significantly different physical properties.Dunes are globally more microwave absorbent than the interdunes. The interdunes present multi-scale roughness with a higher dielectric constant than the dunes. Considering the composition, the interdunes are in between the dunes and the radar bright inselbergs, suggesting the presence of a shallow layer of non-mobilized sediment in between the dunes. Additionally potential secondary bedforms, such as ripples and avalanches, may have been detected. Our findings strongly suggest that sand seas evolve under current multi-directional wind regimes. Consequently sediment inventory and climatic conditions are being re-evaluated.

show abstract

“…As the amount of sand increases in a unidirectional wind regime, the barchan dunes evolve into transverse ridges, which extend perpendicular to the wind direction [ Courrech du Pont , ]. Dune‐dune interactions, amalgamations, and the formation of secondary bed forms result in nonlinear pattern coarsening [ Rubin and Hunter , ; Ewing and Kocurek , ; Kocurek et al ., ; Gao et al ., ], with the average size and wavelength of the transverse dunes increasing during the simulation.…”

Section: Model Verificationmentioning

confidence: 99%

A coupled vegetation/sediment transport model for dryland environments

2017

View full text Add to dashboard Cite

Dryland regions are characterized by patchy vegetation, erodible surfaces, and erosive aeolian processes. Understanding how these constituent factors interact and shape landscape evolution is critical for managing potential environmental and anthropogenic impacts in drylands. However, modeling wind erosion on partially vegetated surfaces is a complex problem that has remained challenging for researchers. We present the new, coupled cellular automaton Vegetation and Sediment TrAnsport (ViSTA) model, which is designed to address fundamental questions about the development of arid and semiarid landscapes in a spatially explicit way. The technical aspects of the ViSTA model are described, including a new method for directly imposing oblique wind and transport directions onto a cell‐based domain. Verification tests for the model are reported, including stable state solutions, the impact of drought and fire stress, wake flow dynamics, temporal scaling issues, and the impact of feedbacks between sediment movement and vegetation growth on landscape morphology. The model is then used to simulate an equilibrium nebkha dune field, and the resultant bed forms are shown to have very similar size and spacing characteristics to nebkhas observed in the Skeleton Coast, Namibia. The ViSTA model is a versatile geomorphological tool that could be used to predict threshold‐related transitions in a range of dryland ecogeomorphic systems.

show abstract

Development and steady states of transverse dunes: A numerical analysis of dune pattern coarsening and giant dunes

Cited by 62 publications

References 85 publications

Elongation and Stability of a Linear Dune

Elongation and Stability of a Linear Dune

Texture and Composition of Titan's Equatorial Sand Seas Inferred From Cassini SAR Data: Implications for Aeolian Transport and Dune Morphodynamics

A coupled vegetation/sediment transport model for dryland environments

Contact Info

Product

Resources

About