Greedy Parabolics: Wind flow direction within the deflation basin of parabolic dunes is governed by deflation basin width and depth

Thomas Smyth, Irene Delgado-Fernandez, DWT Jackson, Brian Yurk, Paul Rooney

Research output: Contribution to journalArticlepeer-review

2 Citations (Scopus)
15 Downloads (Pure)

Abstract

Parabolic dunes are ‘U’ or ‘V’-shaped aeolian landforms that form on pre-existing sand deposits. Their morphology consists of an upwind deflation basin, bordered by often vegetated trailing arms and a downwind depositional lobe. The orientation of parabolic dunes is commonly attributed to the prevailing or resultant wind direction. Consequently, the orientation of parabolic dunes stabilised by vegetation growth has been used as a proxy for wind direction during past climates in several studies. However, the ability or extent of parabolic dune morphology to steer incident wind flow parallel to the orientation of the landform, and thus migrate in the direction of the current landform orientation rather than prevailing wind direction, is unknown.

By numerically modelling wind flow within the deflation basin of eight parabolic dunes, we demonstrate for the first-time, that wind flow direction within the deflation basin of a parabolic dune is highly controlled by the depth and width of the deflation basin. The greater the depth-width ratio of the landform (i.e. the deeper and narrower the deflation basin), the greater the degree of flow steering relative to the axis orientation of the landform. These results demonstrate that future studies must exercise caution when using parabolic dune orientation as a direct proxy for prevailing wind direction, especially where parabolic dunes have a relatively high deflation basin depth-width ratio, as the deflation basin of these landforms may continue to migrate in an antecedent wind direction.
Original languageEnglish
Pages (from-to)643-660
Number of pages18
JournalProgress in Physical Geography: Earth and Environment
Volume44
Issue number5
Early online date23 Jan 2020
DOIs
Publication statusPublished - 1 Oct 2020

Bibliographical note

Funding Information:
We thank Sefton Council for granting permission to carry our work at the Devil?s Hole blowout and for help accessing the site. Robin Davidson-Arnott (University of Guelph) and Alexander Smith provided support for field experiments at the Devil?s Hole. We are grateful to several Edge Hill University research students involved in the fieldwork, namely, Nicholas O?Keeffe, Aneurin O?Neil, Blythe Tinsley, Rachel Platt, and Daniel Bocharnikov. We also acknowledge Dave Rogers (Ulster University) for his help in processing the TLS and GPS data. We also thank Professor Edward Hansen (Hope College, Michigan) for his generous hospitality and feedback. The author(s) disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: This work is funded by Natural England (Grant Ecm_6888). In particular, we thank Graham Weaver at Natural England for his support throughout the project. The work is also a contribution to the U.K. Natural Environment Research Council grant NE/F019483/1.

Funding Information:
The author(s) disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: This work is funded by Natural England (Grant Ecm_6888). In particular, we thank Graham Weaver at Natural England for his support throughout the project. The work is also a contribution to the U.K. Natural Environment Research Council grant NE/F019483/1.

Publisher Copyright:
© The Author(s) 2020.

Copyright:
Copyright 2020 Elsevier B.V., All rights reserved.

Keywords

  • Parabolic dune
  • computational fluid dynamics
  • near-surface wind flow
  • paleowind

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