Vertical distribution of grain size for wind blown sand

Farrell, Eugene; Sherman, Douglas J.; Ellis, Jean T.; Li, Bailiang

doi:10.1016/j.aeolia.2012.03.003

Cited by 93 publications

(115 citation statements)

References 58 publications

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“…This result was completely different from that the mean grain size of sediment flux over sand surfaces decreased monotonously (Arens et al, 2002), increased (Van der Wal, 2000) or first decreased then increased with height (Farrell et al, 2012;Tan et al, 2014;Williams, 1964). Theoretically, it is generally believed that grain size decreases with height above the bed surface, while the coarsening trend of mean grain-size with height requires that the coarser grains have higher launch velocities than finer grains.…”

Section: Grain Size Distribution Of Sediment Fluxcontrasting

confidence: 46%

“…Theoretically, it is generally believed that grain size decreases with height above the bed surface, while the coarsening trend of mean grain-size with height requires that the coarser grains have higher launch velocities than finer grains. The mechanism for the coarsen trend in the mean grain size as a function of height is still unclear (Farrell et al, 2012). The clear decrease in mean grain size above 240 mm seems to be connected with the increase of coarser grains (0.125-0.315 mm) in mass weight while the decrease of finer grains (<0.08 mm) in this layer (Fig.…”

Section: Grain Size Distribution Of Sediment Fluxmentioning

confidence: 95%

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Aeolian sediment transport over gobi: Field studies atop the Mogao Grottoes, China

Tan

Zhang

et al. 2016

Aeolian Research

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a b s t r a c tThis paper reports on field studies of aeolian sediment transport over a rough surface-gobi atop the Mogao Grottoes, China, in relation to sediment entrainment, saltation mass flux and transport rate prediction. Wind speeds were measured with five cup anemometers at different heights and sediment entrainment and transport measured with horizontal and vertical sediment traps coupled to weighing sensors, where sediment entrainment and transport were measured synchronously with wind speeds. Four sediment transport events, with a measurement duration ranging between 2.5 and 11 h, were studied. The entrainment threshold determined by the horizontal sediment trap varied between 0.28 and 0.33 m s À1 , and the effect of non-erodible roughness elements-gravels increased the entrainment threshold approximately by 1.8 times compared to a uniform sand surface. Unlike the non-monotone curve shape of sediment flux density profile over gobi measured in wind tunnels, the flux density profile measured in the field showed an exponential form. Aeolian sediment transport over gobi could be predicted by an Owen-type saltation model: q ¼ Aq=gu Ã ðu 2 Ã À u 2 Ãt Þ, where q is sediment transport rate, A is a soilrelated dimensionless factor, u Ã is the friction velocity, u Ãt is the threshold friction velocity, g is the gravitational acceleration, q is the air density. This study indicates that the sediment flux sampling using horizontal and vertical sediment traps coupled to weighing sensors provides a practical method to determine values for A in this model that can provide good estimates of sediment transport rates in gobi areas.

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Section: Grain Size Distribution Of Sediment Fluxcontrasting

confidence: 46%

Section: Grain Size Distribution Of Sediment Fluxmentioning

confidence: 95%

Aeolian sediment transport over gobi: Field studies atop the Mogao Grottoes, China

Tan

Zhang

et al. 2016

Aeolian Research

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“…Our results are consistent with the findings of Raubenheimer et al [60]. They measured water Our results indicate that higher surface moisture content leads to transport over higher heights compared to dry surfaces, as reported in the literature [32,53,47]. Furthermore, the data show that mean saltation height does remain essentially constant with an increase of u H for dry, moist or wet surfaces.…”

Section: Discussionsupporting

confidence: 95%

Temporal and spatial variability in event scale aeolian transport on Ameland, The Netherlands

Poortinga

Keijsers

Visser

et al. 2015

GeoResJ

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a b s t r a c tCoastal dunes are the primary defence protecting the coastline from the destructive forces of the sea in The Netherlands. Aeolian processes are important in this context as they contribute to dune accretion and thus the safety of the coastal hinterland. In this study, we analyze horizontal and vertical variability of event scale aeolian sand transport on a wide beach on the island of Ameland, The Netherlands. Data were obtained from a meteorological station, groundwater monitoring wells and a camera installed on the beach. Fifteen aeolian transport events (two involving onshore winds, seven longshore and six offshore) were measured using a comprehensive grid of 37 customized MWAC traps. The highest sand transport rates and largest variability was found for alongshore events. Surface moisture, governed by groundwater, was found to be an important controlling parameter for aeolian transport rates and vertical flux profiles. Groundwater levels were largely dominated by beach inundation, influencing the groundwater table for a two week period. Variations in vertical flux profiles between traps were larger for wet sand transport events than dry ones. In general, sand transport rates were highest at the foreshore and lowest at the dune toe. Sand transport dynamics are dependent on local conditions such as beach dimensions, beach orientation and also meteorological and surface characteristics. Moderate (high frequency, low magnitude) events are also capable of transporting large amounts of sand. Future studies should include spatially explicit measurements of elevation and surface moisture to obtain a more complete understanding of the complex sand transport dynamics.

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“…As shown in Figure 3, both in wind-tunnel and field measurements the mean diameters of saltating particles above 2 cm height are approximately constant with height. More recently, Farrell et al14 analyzed the vertical distribution of saltating particles, and also found a inflection region between 0.05 and 0.15 m height above the surface, in which the mean diameter is invariant to changes in height. It means that the mean diameters may slightly affect the variation of charge-to-mass ratios with height within the saltation layer.…”

Section: Resultsmentioning

confidence: 99%

Charge-to-mass Ratio of Saltating Particles in Wind-Blown Sand

Zhang

Zheng

2014

Sci Rep

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The electrification of sand particles plays an important role in aeolian events. In this paper, the charge-to-mass ratio vertical profiles of saltating particles in wind-blown sand were measured by a field experiments. By combining the results of field measurements with our previous wind-tunnel measurements, we discussed the factors affecting the charge-to-mass ratio of saltating particles. It reveals that the magnitude of the charge-to-mass ratio increases exponentially with height above the surface. In addition, the charge polarity of saltating particles depends on the relative size between saltating and creeping particles, and the magnitude of charge-to-mass ratio is determined by wind velocity and the relative size difference ratio between saltating and creeping particles.

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Vertical distribution of grain size for wind blown sand

Cited by 93 publications

References 58 publications

Aeolian sediment transport over gobi: Field studies atop the Mogao Grottoes, China

Aeolian sediment transport over gobi: Field studies atop the Mogao Grottoes, China

Temporal and spatial variability in event scale aeolian transport on Ameland, The Netherlands

Charge-to-mass Ratio of Saltating Particles in Wind-Blown Sand

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