Phase diagrams of dune shape and orientation depending on sand availability

Gao, Xin; Narteau, C.; Rozier, Olivier; Pont, Sylvain Courrech du

doi:10.1038/srep14677

Cited by 73 publications

(99 citation statements)

References 40 publications

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“…An emerging body of numerical and experimental work [e.g., Courrech du Pont et al ., ; Gao et al ., ; Lucas et al ., ] suggests that sediment availability not only controls dune type but also the dune orientation, due to a variation in the dune growth mechanism. Two modes for dune orientation, the “fingering” and “bed instability” modes, have been identified by Courrech du Pont et al [].…”

Section: Model Verificationmentioning

confidence: 99%

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A coupled vegetation/sediment transport model for dryland environments

2017

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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.

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Section: Model Verificationmentioning

confidence: 99%

“…Text S6 provides detailed analysis of the experimental results. The diversity of patterns produced in these experiments supports the notion that sediment availability controls both dune type and orientation [ Courrech du Pont et al ., ; Gao et al ., ; Lucas et al ., ].…”

Section: Model Verificationmentioning

confidence: 99%

A coupled vegetation/sediment transport model for dryland environments

2017

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“…A change from barchan and crescentic dunes in the lower unit to sinuous transverse dunes in the upper unit records an increase in sediment availability and a more developed dune field pattern higher in the section. Barchan dunes form in the early stages of dune field development (Bagnold, ; Elbelrhiti, ; Howard et al, ; Wasson & Hyde, ), when sediment availability is relatively limited (Courrech du Pont et al, ; Gao et al, ). As the dunes migrate, they combine, grow larger, and link together, eventually forming ridges of transverse dunes oriented normal to the direction of net sediment transport when sediment availability is high (Kocurek et al, ; Rubin & Hunter, ).…”

Section: Unit Descriptions and Interpretationsmentioning

confidence: 99%

Ancient Stratigraphy Preserving a Wet‐to‐Dry, Fluvio‐Lacustrine to Aeolian Transition Near Barth Crater, Arabia Terra, Mars

2019

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Ancient lacustrine and aeolian sediments have been separately identified in a variety of locations on Mars. In this work, we interpret the depositional history of Barth crater and its surrounding area in Arabia Terra where exposed geologic units preserve a record of lacustrine and aeolian interaction. Aeolian sandstone in the study area overlies lacustrine strata and is interbedded with easily eroded interdune deposits. The aeolian sandstone preserves dune strata with structures that indicate paleo‐sediment transport toward the northwest. The aeolian unit also preserves a transition up‐section from separated barchan dunes to continuous transverse dunes, capturing the development of the ancient dune field from sediment limited to sediment rich. Inverted fluvial channels provide evidence that water was delivered to the area at the same time the dune field was present, providing a simple mechanism, via wetting and cementation, for aeolian strata preservation. This example of wet‐system aeolian accumulation preserves an upward drying sequence in the sedimentary record that may have been coincident with the widely hypothesized global climate transition. The terrains described in this work provide a framework for interpreting similar aeolian units in elsewhere on Mars, even where cross‐strata cannot be easily resolved.

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“…Also referred to as seif dunes (Lancaster, ; Tsoar, ) or silks (Mainguet & Callot, ) when they are sinuous, these finger‐like structures are widespread on Earth and other planetary bodies. They develop on nonerodible beds submitted to multidirectional flow regimes thanks to the deposition at the dune tips of the sediment transported along the crests (Courrech du Pont et al, ; Gao et al, ). Sometimes, the upstream source of sediment is fixed, like for lee dunes elongating behind a topographic obstacle (Tsoar, ).…”

Section: Introductionmentioning

confidence: 99%

Elongation and Stability of a Linear Dune

Rozier

Narteau

Gadal

et al. 2019

Geophysical Research Letters

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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.

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Phase diagrams of dune shape and orientation depending on sand availability

Cited by 73 publications

References 40 publications

A coupled vegetation/sediment transport model for dryland environments

A coupled vegetation/sediment transport model for dryland environments

Ancient Stratigraphy Preserving a Wet‐to‐Dry, Fluvio‐Lacustrine to Aeolian Transition Near Barth Crater, Arabia Terra, Mars

Elongation and Stability of a Linear Dune

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