Morphology and dynamics of star dunes from numerical modelling

Zhang, Deguo; Narteau, C.; Rozier, Olivier; Pont, Sylvain Courrech du

doi:10.1038/ngeo1503

Cited by 113 publications

(91 citation statements)

References 26 publications

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“…Linear dunes typically form under bidirectional wind regimes when the divergence angle is greater than 100° (Rubin and Ikeda, 1990;Parteli et al, 2009;Reffet et al, 2010). More complicated star dunes with three or more slip faces are produced when strong winds blow from several directions, with higher frequencies of wind reorientation promoting growth and decreasing arm dimensions (Zhang et al, 2012).…”

Section: Aeolian Bedforms On Earthmentioning

confidence: 99%

Bedform migration on Mars: Current results and future plans

et al. 2013

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Section: Aeolian Bedforms On Earthmentioning

confidence: 99%

Bedform migration on Mars: Current results and future plans

et al. 2013

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“…Compared with our previous field investigations in other mid-latitude deserts, other dune types such as pyramid or star dunes occur widely in the Taklamakan and the Badanjilin deserts (Yang et al 2011a;Zhu and Yang 2009;Zhu and Yu 2014;Zhu et al 2014c). Observations and simulations in the Taklamakan Desert show that some pyramid dunes have been created by erosive processes and in the Badanjilin Desert the multi-directional winds presumably played an important role in the creation of the star dunes (Yang et al 2004;Zhang et al 2013). Although seasonal change in the direction of prevailing winds is apparent in the meteorological records from the Ejina weather station (Fig.…”

Section: Landform Instability In the Ejina Basin And Its Environmentamentioning

confidence: 96%

Geomorphoclimatic characteristics and landform information in the Ejina Basin, Northwest China

Zhu

Rioual

et al. 2014

Environ Earth Sci

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Natural environment of mid-latitude deserts of Central Asia is undergoing rapid changes. One of its elements is the relief. What needs to be particularly emphasized is its morphogenesis and landform evolution. In this study, a geomorphological research in the Ejina Basin (Inner Mongolia) is carried out with regard to identifying the main landforms and the contemporary geomorphic processes. We consider ancient and modern landforms as a unit and provide a general explanation for their evolution. Related environmental indications of existing landforms are discussed on the basis of climate geomorphology. Results show that the current basin is under the conditions favorable for the development and dominance of landforms originated from physical processes such as desiccationdeflation and aeolian. The landform system is characterized by its variable structure which is conditioned by specific hydrodynamics processes that existed during glaciations. It is suggested that landform patterns in Ejina are under the strong influence of rapid and/or intensive geomorphic processes. These signatures reflect the regional dynamics of landform evolution as characterized by a very effective integration of tectonic and climate-driven morphogenetic processes. Based on the present day climate data, we infer an obvious linkage of desert gorges and pediments in the basin to ancient humid phases, which provided high energy runoff for the formation of these landforms and were associated with erosional features under more humid and colder climate during the last glacial period. Desert plains and aeolian dunes in the central basin are the related products of contemporary climate. Clear evidences proving the landform inconsistency and landform instability in the Ejina are presented, indicating that the main geomorphic unit is experiencing transformation from alluvial plain to desert plain and then to aeolian dunes. However, the geomorphodiversity in the Ejina should be a compound result of complex surficial processes other than glaciation. Frost weathering, fluvial/alluvial action, desiccation-deflation and aeolian processes as well as climatic changes have played important roles.

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“…Although CA modelling is effective at creating realistic dune forms under a range of conditions such as wind direction (Zhang et al, 2012) and vegetation (Nield and Baas, 2008), the simple assumptions determining the models outcome cannot yet be used to predict morphological change in reality (Zheng, 2009). Furthermore the two-dimensional nature of flow modelling conducted in CA modelling does not permit users to adequately investigate lateral patterns of deposition or erosion that may occur.…”

Section: Dune Morphological Modellingmentioning

confidence: 99%

Aeolian dynamics of beach scraped ridge and dyke structures

Smyth

Hesp

2015

Coastal Engineering

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Where urban areas are situated close to a beach, sand dunes act as protection from flooding and erosion. When a dune has been removed or damaged by erosion, dune, ridge or dyke re-building using heavy machinery, a process known as beach scraping, is a common method of restoration. Following construction, natural accretion of sediment on the backshore is preferable as it facilitates sustained natural dune building, growth of vegetation, habitat creation and reduces the need for further beach scraping.This study investigates the near surface flow and transport potential for three artificial structure designs: a single ridge, a double ridge and a dyke. The three shapes contained an identical volume of sand and were preceded by 50 m of beach at an angle of 3°. A computational fluid dynamic model (CFD) was created for each scenario to calculate wind flow and shear velocity from 4 different wind directions at 22.5° intervals from 0° (onshore) to 67.5°. From this data sediment flux was predicted along a two dimensional transect for each of the scenarios.For all structures, shear velocity on the beach and stoss slope decreased as incident wind direction became more oblique, conversely shear velocity in the lee of the crest increased. A reduction in shear velocity at the foot of each structure also occurred and appears related to stoss slope, with the reduction greatest reduction at the toe of the dyke structure (stoss slope 34°) and the least before the single ridge (stoss slope 17°).Specifically the results suggest that the double ridge structure is the most resilient to aeolian erosion. Shear velocity reduction on the back beach is comparable to the dyke and sediment flux from the stoss slope of the double ridge structure may become trapped in the swale between the two ridges encouraging sediment deposition, thus reducing sediment transport beyond the dunes and backshore. Although the dyke structure underwent the greatest reduction in shear velocity on the back beach it experienced substantial sediment flux at the crest and along the top of the structure, making it susceptible to erosion during a strong wind event. The highest sediment transport rate was calculated at the crest of the single ridge, and the single ridge structure also created the smallest reduction of shear velocity on the back beach, thus making it less desirable than the double ridge.

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Morphology and dynamics of star dunes from numerical modelling

Cited by 113 publications

References 26 publications

Bedform migration on Mars: Current results and future plans

Bedform migration on Mars: Current results and future plans

Geomorphoclimatic characteristics and landform information in the Ejina Basin, Northwest China

Aeolian dynamics of beach scraped ridge and dyke structures

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