Climate as a control on foredune mode in Southern Australia

García‐Romero, Leví; Hesp, Patrick A.; Peña‐Alonso, Carolina; Silva, Graziela Miot da; Hernández‐Calvento, Luis

doi:10.1016/j.scitotenv.2019.133768

Cited by 22 publications

(10 citation statements)

References 74 publications

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“…Foredunes vary from scattered discrete nebkha (Hernandez‐Calvento et al, 2017; Hernández‐Cordero et al, 2015; Mountney & Russell, 2006; Ruz et al, 2017) to continuous ridges (García‐Romero et al, 2019; Hesp, 2002; Hesp et al, 2021). While some studies have been conducted on nebkha flow dynamics and their attendant shadow dunes (e.g., Hesp & Smyth, 2017; Mayaud et al, 2016a, 2016b), and several studies have been conducted on flow over foredune ridges with one dominant species (Arens et al, 1995; Bauer & Davidson‐Arnott, 2014; Buckley, 1987; Davidson‐Arnott & Law, 1996; Delgado‐Fernandez et al, 2011; Grilliot et al, 2018; Hart et al, 2012; Hesp, 1989; Hesp et al, 2013, 2015; Hilton et al, 2016; Jackson et al, 2013; Keijsers et al, 2015; Nordstrom et al, 2006; Sarre, 1987; Schwarz et al, 2021; Wakes et al, 2010, 2021; Walker, Davidson‐Arnott, et al, 2009), there are few studies on the stoss slope of a natural foredune where there are neighbouring zones of significantly different vegetation cover.…”

Section: Introductionmentioning

confidence: 99%

Air flow and sediment transport dynamics on a foredune with contrasting vegetation cover

Bauer

Hesp

Smyth

et al. 2022

Earth Surf Processes Landf

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Wind flow and sediment transport across a northern California beach‐foredune system with two adjacent vegetation types are examined for the same incident wind conditions. The invasive Ammophila arenaria was taller (c. 1 m) with denser coverage than the neighbouring Elymus mollis alliance canopy (c. 0.65 m), which consisted of a variety of interspersed native plants. Wind flow was measured with rotating cup and sonic anemometry, while sediment transport was measured using laser particle counters. Wind speed profiles over the two canopies were significantly different because of differing vegetation height, coverage density, and stem stiffness. In both cases, there was a lower zone of semi‐stagnant air (below about 0.3 m) that transitioned upward to a shear zone comprising the upper part of the canopy and immediately above. The shear zone above the Elymus canopy was relatively thin (confined to 0.3–0.5 m above‐ground) whereas the shear zone in the Ammophila canopy was thicker extending from a height of about 0.5h (h is average plant height) to about 1.5h. Vertical profiles of Reynolds shear stress (RSS) and turbulence kinetic energy (TKE) are consistent with the shear layer structure over these two contrasting vegetation canopies. The degree of topographically‐forced and vegetation‐enhanced flow steering was significant, with Ammophila strongly shifting the highly oblique (55°) incident wind to essentially shore‐perpendicular trajectories. In comparison, the shore‐perpendicular steering effect was not as pronounced for the Elymus canopy. Sediment transport intensity on the beach was continuous, but decreased progressively to the dune toe, and then dropped to essentially zero once the vegetation canopy was encountered (on the stoss slope). Overall, the study illustrates the significant differences in wind flow and turbulence conditions that may occur in contrasting plant canopies on foredunes, suggesting that greater attention needs to be placed on vegetation roughness characteristics in models of foredune morphodynamics and sediment transport potential.

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Section: Introductionmentioning

confidence: 99%

Air flow and sediment transport dynamics on a foredune with contrasting vegetation cover

Bauer

Hesp

Smyth

et al. 2022

Earth Surf Processes Landf

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“…When formed in temperate zones, these nebkhas have been defined as an erosive phase of the dune field that is typical of these environments [38]. However, they can also be found in arid regions, where continuous foredunes do not build up [38][39][40]. Such is the case in the Canary Islands, where the dry climate conditions present at coastal level only allow the formation of nebkhas, mainly associated with the nanerophytic bush Traganum moquinii [41][42][43][44].…”

Section: Methodsmentioning

confidence: 99%

A DIY Low-Cost Wireless Wind Data Acquisition System Used to Study an Arid Coastal Foredune

Domínguez‐Brito

Cabrera‐Gámez

Viera-Pérez

et al. 2020

Sensors

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Environmental studies on coastal dune systems are faced with a considerable cost barrier due to the cost of the instrumentation and sensory equipment required for data collection. These systems play an important role in coastal areas as a protection against erosion and as providers of stability to coastal sedimentary deposits. The DIY (Do-It-Yourself) approach to data acquisition can reduce the cost of these environmental studies. In this paper, a low-cost DIY wireless wind data acquisition system is presented which reduces the cost barrier inherent to these types of studies. The system is deployed for the analysis of the foredune of Maspalomas, an arid dune field situated on the south coast of Gran Canaria (Canary Islands, Spain), for the specific purpose of studying the dynamics of a dune type (tongue dunes), which is typical of this environment. The results obtained can be of interest for the study of these coastal environments at both the local level, for the management of this particular dune field, and at the general level for other similar dune fields around the world.

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“…That climatic conditions were drier during the formation of 'chevrons' and of coeval linear dunes is attested to by the occurrence of nebkhas within these deposits (Tormey, 1999;Kindler & Strasser, 2000). Indeed, nebkhas, or 'coppice dunes', characterize areas of low precipitation ranging from 200 to 300 mm yr −1 (García-Romero et al, 2019). In comparison, today's annual rainfall across the Bahamas varies between 600 mm and 1500 mm (Wolcott et al, 2018).…”

Section: Age Of 'Chevrons'mentioning

confidence: 99%

Upper Pleistocene parabolic ridges (i.e. ‘chevrons’) from the Bahamas: Storm‐wave sediments or aeolian deposits? A quantitative approach

et al. 2021

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The Upper Pleistocene (Marine Isotope Stage 5e; ca 120 ka) stratigraphic record from the Bahamas comprises large, kilometre-long parabolic ridges of oolitic composition, that point landward, and have been up to now called 'chevrons'. A debate about their genesis has led previous researchers to consider two processes of deposition: (i) a catastrophic event involving giant storm-generated waves produced by specific climatic conditions at the end of Marine Isotope Stage 5e; and (ii) a more uniformitarian process which characterizes 'chevrons' as aeolian parabolic dunes because of their similar morphology. Since there are few unequivocal sedimentological criteria to discriminate aeolian from water-deposited sediments, only a quantitative, multi-method approach could provide enough evidence to produce a viable diagnosis on the genetic processes involved. Following this reasoning, the quantification of the morphological parameters of 'chevrons', a precise study of their sedimentary structures on previously and newly discovered sections, and several statistical grain-size analyses, all advocate for an aeolian origin. Moreover, when the aforementioned characteristics of 'chevrons' are compared with those of storm deposits (for example, washovers) and parabolic dunes occurring elsewhere on Earth, the dissimilarity with the former and the resemblance with the latter is evident. Amino-acid racemization dating, together with stratigraphic and petrographic investigations, constrain the age of the 'chevrons' to the late part of Marine Isotope Stage 5e. Their occurrence during this specific time interval can be explained by both strengthened easterly winds and drier climatic conditions associated with changing vegetation cover. Fixation of the arms by sparse vegetation, coupled with the loose 'chevron' nose sediment migrating farther inland, form the peculiar U-shaped morphology of these ridges.

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Climate as a control on foredune mode in Southern Australia

Cited by 22 publications

References 74 publications

Air flow and sediment transport dynamics on a foredune with contrasting vegetation cover

Air flow and sediment transport dynamics on a foredune with contrasting vegetation cover

A DIY Low-Cost Wireless Wind Data Acquisition System Used to Study an Arid Coastal Foredune

Upper Pleistocene parabolic ridges (i.e. ‘chevrons’) from the Bahamas: Storm‐wave sediments or aeolian deposits? A quantitative approach

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