Aeolian vertical mass flux profiles above dry and moist sandy beach surfaces

Rotnicka, Joanna

doi:10.1016/j.geomorph.2012.12.032

Cited by 52 publications

(42 citation statements)

References 36 publications

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“…Furthermore, the data show that mean saltation height does remain essentially constant with an increase of u H for dry, moist or wet surfaces. This is in agreement with the finding of Namikas [51], Namikas et al [50], Rotnicka [65] and the model proposed by Namikas [52], that increasing saltation impact energy levels that occur with large u H are dissipated by bed deformation and increased impact entrainment rather than contributing to larger saltation hops. The cohesive forces imparted by water allow wet grains to resist entrainment considerably more than dry grains, so that more impact energy is retained on wet surfaces and thus higher saltation paths are generated.…”

Section: Discussionsupporting

confidence: 93%

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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Section: Discussionsupporting

confidence: 93%

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

Poortinga

Keijsers

Visser

et al. 2015

GeoResJ

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“…Flow compression up the windward side of the dune leading to near‐surface overspeed regions at the crest may have significant ramifications for the shape of these particle flux profiles and the overall structure of saltation layers. Nevertheless, the general trends shown in Figures and are not unlike those described by other researchers [e.g., Williams , ; Rasmussen and Mikkelsen , ; Li and Ni , ; Gu and Guo , ; Xing , ; Ellis et al ., ; Dong et al ., ; Rotnicka , ] in the sense that the profiles can be well described statistically by an exponential decay function (equation ), despite having a prominent foot region.…”

Section: Resultsmentioning

confidence: 99%

“…In contrast, Dong et al . [] interpreted the differences in flux profiles as originating in the character of the dune surfaces (i.e., presence of biocrusts, bedforms, and vegetation) over which measurements were taken, whereas surface moisture content has also been shown to exert a strong control on the vertical flux profile [ Rotnicka , ]. Ho et al .…”

Section: Introductionmentioning

confidence: 99%

Aeolian particle flux profiles and transport unsteadiness

Bauer

Davidson‐Arnott

2014

JGR Earth Surface

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Vertical profiles of aeolian sediment flux are commonly modeled as an exponential decay of particle (mass) transport with height above the surface. Data from field and wind-tunnel studies provide empirical support for this parameterization, although a large degree of variation in the precise shape of the vertical flux profile has been reported. This paper explores the potential influence of wind unsteadiness and time-varying intensity of transport on the geometry (slope, curvature) of aeolian particle flux profiles. Field evidence from a complex foredune environment demonstrates that (i) the time series of wind and sediment particle flux are often extremely variable with periods of intense transport (referred to herein as sediment "flurries") separated by periods of weak or no transport; (ii) sediment flurries contribute the majority of transport in a minority of the time; (iii) the structure of a flurry includes a "ramp-up" phase lasting a few seconds, a "core" phase lasting a few seconds to many tens of seconds, and a "ramp-down" phase lasting a few seconds during which the system relaxes to a background, low-intensity transport state; and (iv) conditional averaging of flux profiles for flurry and nonflurry periods reveals differences between the geometry of the mean profiles and hence the transport states that produce them. These results caution against the indiscriminate reliance on regression statistics derived from time-averaged sediment flux profiles, especially those with significant flurry and nonflurry periods, when calibrating or assessing the validity of steady state models of aeolian saltation.

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“…In addition, individual researchers use various measurement methods of aeolian transport on the beach and foredunes, which complicates the comparison of the results. Typically, vertical sand traps having various sizes and shapes, and thus different efficiency, are used (Arens, van der Lee 1995;Borówka, Rotnicki 1999;Borówka 1980Borówka , 1990Borówka , 2001Leatherman 1978;Łabuz 2005;Riabichin 1969;Rotnicka 2011aRotnicka , 2011bRotnicka , 2013a.…”

Section: Study Areamentioning

confidence: 99%

Influence of meteorological conditions on aeolian processes along the Polish cliff coast

Hojan

Więcław

2014

Baltica

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This article presents aeolian landforms and meteorological parameters affecting aeolian processes on the south Baltic coastal cliffs of Poland. The analysis was conducted for two weather stations at different locations. The bluffs in the vicinity of the stations have similar geological structure, but differ in height. Velocity and direction of the wind, as well as precipitation, are of dominating importance. Dispelling the cliff starts at wind speeds of two-three ms -1 . At this speed, the distance at which the material is transported is short and is only a few meters, while for the transport of fine sand and dust on the top of the bluff the wind speed must be over 10 ms -1 . It was observed that such speeds of the wind or gust is characteristic of days with an average wind velocity of at least six ms -1 . The number of days with potential deflation on the bluff is four times higher in the area of Ustka than in the Świnoujście region. On average, the bluff in Ustka can be dispersed by wind throughout 33 days in a year, while the one on Wolin Island in less than eight days. Erosive and accumulative eolian forms are small, their sizes are generally less than one meter, only with rhythmic swelling to the size of several meters.

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Aeolian vertical mass flux profiles above dry and moist sandy beach surfaces

Cited by 52 publications

References 36 publications

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

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

Aeolian particle flux profiles and transport unsteadiness

Influence of meteorological conditions on aeolian processes along the Polish cliff coast

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