Airflow and aeolian sediment transport patterns within a coastal trough blowout during lateral wind conditions

Smyth, T.A.G. and Jackson, D.W.T. and Cooper, J.A.G. (2014) Airflow and aeolian sediment transport patterns within a coastal trough blowout during lateral wind conditions. Earth Surface Processes and Landforms, 39 (14). pp. 1847-1854. ISSN 1096-9837

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Abstract

Blowouts are depressions that occur on coastal dunes, deserts and grasslands. The absence of vegetation in blowouts permits high speed winds to entrain and remove sediment. Whereas much research has examined patterns of wind flow and sediment transport on the stoss slopes and lee of sand dunes, no study has yet investigated the connections between secondary air-flow structures and sediment transport in a blowout where zones of streamline compression, expansion and steering are less
clearly delineated. In this study we investigated the variability of sediment flux and its relation to near-surface wind speed and turbulence within a trough blowout during wind flow that was oblique to the axis of the blowout. Wind flow was measured using six, three-dimensional (3D) ultrasonic anemometers while sediment flux by eight sand traps, all operating at 25 Hz.
Results demonstrated that sediment flux rates were highly variable throughout the blowout deflation basin, even over short distances (< 0.5 m). Where flow was steadiest, flux was greatest. Consequently the highest rates of sediment transport were recorded on the erosional wall crest where flow was compressed and accelerated. The strength of correlation between sediment flux and wind
parameter improved with an increase in averaging interval, from 10 seconds to 1 minute. At an interval of 10 seconds, however, wind speed correlated best with flux at seven of eight traps, whereas at an interval of one minute Turbulent Kinetic Energy (TKE) provided the best correlation with flux at six of the eight traps. Correlation between sediment flux and wind parameters was best in the centre of the blowout and poorest on the erosional wall crest. The evidence from this paper suggests, for the first time, that TKE may be a better predictor of sediment transport at minute scale averaging intervals, particularly over landforms where wind flow
is highly turbulent.

Item Type:	Article
Additional Information and Comments:	This is the peer reviewed version of the following article: Smyth T. A. G., Jackson D., and Cooper A. (2014), Airflow and aeolian sediment transport patterns within a coastal trough blowout during lateral wind conditions, Earth Surface Processes and Landforms, 39 (14), pp 1847–1854, which has been published in final form at https://onlinelibrary.wiley.com/doi/pdf/10.1002/esp.3572. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving.
Faculty / Department:	Faculty of Human and Digital Sciences > School of Computer Science and the Environment
Depositing User:	Thomas Smyth
Date Deposited:	14 Jun 2018 08:22
Last Modified:	13 Jan 2025 10:56
URI:	https://hira.hope.ac.uk/id/eprint/2529

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