Airflow dynamics over a beach and foredune system with large woody debris

Michael J. Grilliot, Ian Walker, Bernard O. Bauer

Research output: Contribution to journalArticlepeer-review

4 Scopus citations

Abstract

Airflow dynamics over beach-foredune systems can be complex. Although a great deal is known about the effects of topographic forcing and vegetation cover on wind-field modification, the role of large woody debris (LWD) as a roughness element and modifier of boundary layer flow is relatively understudied. Individual pieces of LWD are non-porous elements that impose bluff body effects and induce secondary flow circulation that varies with size, density, and arrangement. Large assemblages of LWD are common on beaches near forested watersheds and collectively have a degree of porosity that increases aerodynamic roughness in ways that are not fully understood. A field study on a mesotidal sandy beach with a scarped foredune (Calvert Island, British Columbia, Canada) shows that LWD influences flow patterns and turbulence levels. Overall mean and fluctuating energy decline as flow transitions across LWD, while mean energy is converted to turbulent energy. Such flow alterations have implications for sand transport pathways and resulting sedimentation patterns, primarily by inducing deposition within the LWD matrix.

Original languageEnglish (US)
Article number147
JournalGeosciences (Switzerland)
Volume8
Issue number5
DOIs
StatePublished - May 2018

Keywords

  • Aeolian geomorphology
  • Beach-dune morphodynamics
  • Foredune
  • Large woody debris
  • Quadrant events
  • Roughness elements
  • Turbulence
  • Ultrasonic anemometry

ASJC Scopus subject areas

  • Earth and Planetary Sciences(all)

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