The effects of surface moisture on aeolian sediment transport threshold and mass flux on a beach

Robin G D Davidson-Arnott, Yanqi Yang, Jeff Ollerhead, Patrick A. Hesp, Ian Walker

Research output: Contribution to journalArticle

96 Citations (Scopus)

Abstract

This paper presents results from a study designed to explore the effects of beach surface moisture and fetch effects on the threshold of movement, intensity of sand transport by wind and mass flux. The experiment was carried out over a period of five weeks at Greenwich Dunes, Prince Edward Island, Canada in May and June 2002. Moisture content was measured with a Delta-T moisture probe over a 50 m by 25 m grid established on the beach. Measurements of wind speed and direction were made with arrays of cup anemometers and a two-dimensional sonic anemometer. Transport intensity was measured at a height of 2-4 cm above the bed using omnidirectional saltation probes which count the impact of saltating grains on a piezoelectric crystal. Anemometers and saltation probes were sampled at 1 Hz. Sand transport was measured with vertical integrating sand traps over periods of 10-20 minutes. Results show that where there is a considerable supply of dry sand the saltation system responds very rapidly (1-2 s) to fluctuations in wind speed, i.e. to wind gusts. Where sand supply from the surface is limited by moisture, mean transport rates are much lower and this reflects in both a reduction in the instantaneous transport rate and in a transport system that becomes increasingly intermittent. Threshold wind speed is significantly correlated with an increase in surface moisture content near the upwind end of the beach fetch, but the relationship is not significant at the downwind end where sediment transport is initiated primarily by saltation impact from upwind. Mass flux increases with increasing fetch length and the relationship is described best by a power function. Further work is necessary to develop a theoretical function to predict the increase in transport with fetch distance as well as the critical fetch distance.

Original languageEnglish (US)
Pages (from-to)55-74
Number of pages20
JournalEarth Surface Processes and Landforms
Volume33
Issue number1
DOIs
StatePublished - Jan 2008
Externally publishedYes

Fingerprint

fetch
saltation
sediment transport
beach
moisture
anemometer
sand
wind velocity
probe
transport system
moisture content
fluctuation
agricultural product
gust
Canada
supply
wind direction
experiment
dune
effect

Keywords

  • Aeolian sand transport
  • Beach surface moisture
  • Coastal sand dunes
  • Fetch length
  • Thresholds

ASJC Scopus subject areas

  • Geography, Planning and Development
  • Earth-Surface Processes
  • Earth and Planetary Sciences (miscellaneous)

Cite this

The effects of surface moisture on aeolian sediment transport threshold and mass flux on a beach. / Davidson-Arnott, Robin G D; Yang, Yanqi; Ollerhead, Jeff; Hesp, Patrick A.; Walker, Ian.

In: Earth Surface Processes and Landforms, Vol. 33, No. 1, 01.2008, p. 55-74.

Research output: Contribution to journalArticle

Davidson-Arnott, Robin G D ; Yang, Yanqi ; Ollerhead, Jeff ; Hesp, Patrick A. ; Walker, Ian. / The effects of surface moisture on aeolian sediment transport threshold and mass flux on a beach. In: Earth Surface Processes and Landforms. 2008 ; Vol. 33, No. 1. pp. 55-74.
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