Field Evidence for the Initiation of Isolated Aeolian Sand Patches

Delorme, Pauline; Nield, Joanna M.; Wiggs, Giles F.S.; Baddock, Matthew C.; Bristow, Nathaniel; Best, James L.; Christensen, Kenneth T.; Claudin, Philippe

doi:10.1029/2022gl101553

Cited by 6 publications

(4 citation statements)

References 52 publications

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“…Moreover, Delorme et al. (2023) demonstrated that the difference in the amount of sand that is on the ground induces a variation in the sand transport dynamics and thus causes the sand patches formation on the bed surface. In summary, the sand supply thickness is not only a characterization parameter of the amount of sand on the ground but also a crucial parameter that affects the sand transport characteristics.…”

Section: Discussionmentioning

confidence: 99%

Temporal Evolution of Dune Number Density in a Barchan Dune Field

2023

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The present work examines the temporal evolution of dune number density in desert barchan dune fields and the effects of wind velocity, particle diameter and sand supply thickness using the Comprehensive Scale‐Coupled Model of dune field considering turbulence. Results show that the dune number density exhibits a temporal evolution trend of “increase—decrease—tend to be stable,” which is similar to the “overshoot” phenomenon of the per unit width sand transport rate evolving with time. The larger the wind velocity and the smaller the particle diameter are, the enhanced surface sand transport by wind causes the dune number density peak to be larger and appear earlier, but the more active dune interactions result in a higher decay rate during the decline stage. In addition, a small sand supply thickness slows sand accumulation and thus delays the initial development of barchans. With an increase in the sand supply thickness, more small‐scale barchans are formed earlier in dune fields due to gradually sufficient sand amounts, which promotes dune interactions and thus accelerates the decay of dune number density. Nevertheless, as the sand supply thickness continuously increases, the barchans link together to form dune chains, resulting in a slowed migration velocity and a reduced spatial density of interactions. The present work makes up for the lack of understanding of the initial evolution stage of barchan dune fields and the dune interactions in existing studies, and thus may be helpful for gaining insight into the dynamic evolution process of aeolian dune systems.

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Section: Discussionmentioning

confidence: 99%

Temporal Evolution of Dune Number Density in a Barchan Dune Field

2023

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“…To illustrate this agreement, we compared our model Furthermore, the size of the non-vegetated aeolian bedforms on the beach surface for the landward propagation mode (Figure 7a) did not correspond with the bedforms observed in real beach environments. Non-vegetated bedforms on the beach can range in height from small ripples of a few centimeters [23] to larger sand patches with heights of tens of centimeters [58][59][60][61]. For the default jumping length, which produced the landward propagation mode in the wide and prograding beach scenario, bedforms on the beach surface were predicted to have heights in the order of a meter (Figure 7a), much greater than the observed dimensions in the field.…”

Section: Beach-dune Dynamics and Sediment Transport Modesmentioning

confidence: 92%

Conceptualizing Aeolian Sediment Transport in a Cellular Automata Model to Simulate the Bio-Geomorphological Evolution of Beach–Dune Systems

Teixeira

Horstman

Wijnberg

2023

JMSE

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Understanding the dynamics of beach–dune systems is crucial for effective coastal management. The cellular automata model DuBeVeg provides a powerful tool for simulating and understanding the bio-geomorphological evolution of these systems, capturing key interactions of aeolian, hydro-, and vegetation dynamics in a simplified manner. In this study, we present an alternative representation of the aeolian transport component in DuBeVeg, aiming to better capture the saltation transport mode that prevails on beaches. This new representation is compared with the original aeolian transport representation in DuBeVeg, which is inspired by ripple migration. For three beach width scenarios, we considered the effects of the different aeolian transport representations on the predicted foredune morphology after 50 years, as well as the spatio-temporal evolution of the beach–dune system leading to that morphologic state. The saltation transport representation resulted in a more realistic simulation of the seaward expansion of the foredune compared with the original representation, particularly in scenarios with wide and prograding beaches. The new representation also more accurately captured the amplitude of aeolian bedforms emerging across the beach. These findings highlight the importance of selecting the representative transport mode when simulating the transient bio-geomorphological evolution of beach–dune systems.

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“…Proto-dunes are not included in the categorization tree because as transitional features between sand sheets and dunes they may not be identifiable as distinct shapes. However, we note them here for disambiguation and completeness [55,56,57,58].…”

Section: Free Dunesmentioning

confidence: 99%

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

Courrech du Pont,

Rubin,

Narteau

et al. 2024

Preprint

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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 other planetary bodies, including Venus, Mars, Saturn’s moon Titan, and Pluto. Despite the relatively basic conditions required for their formation, dunes adopt a rich diversity of shapes, sizes, and behaviors in response to their boundary conditions and other environmental forcings. Thus, people around the globe and over centuries have developed a rich vocabulary to describe dunes and their complexity. In addition, many studies have been devoted to link dune shape to environmental forcings, usually by means of correlations. As a result, existing dune nomenclature often includes redundant terms with differing definitions across scientific communities. Although a worthy first step, correlation-based classifications can be misleading if not based on an underlying mechanics and if dune morphogenetic classes are not uniquely defined. Here, we synthesize existing dune terminology and put the last two decades of research on dune morphodynamics in perspective in proposing three simplified dune classification schemes based on the state-of-the-art understanding of dune morphology, morphogenetic processes and coupling between sand bed, fluid flow and sediment transport. Together, these classifications provide 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.

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Field Evidence for the Initiation of Isolated Aeolian Sand Patches

Abstract: Sand patches can emerge on non-erodible surfaces.• Differing surface characteristics control particle behaviour.• Field measurements demonstrate the key role of sand transport in bedform initiation.

Cited by 6 publications

References 52 publications

Temporal Evolution of Dune Number Density in a Barchan Dune Field

Temporal Evolution of Dune Number Density in a Barchan Dune Field

Conceptualizing Aeolian Sediment Transport in a Cellular Automata Model to Simulate the Bio-Geomorphological Evolution of Beach–Dune Systems

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

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