Field Study of Beach Water Content as a Guide to Wind Erosion Potential

Darke, Ian B.; Neuman, Cheryl McKenna

doi:10.2112/00-000.1

Cited by 38 publications

(32 citation statements)

References 24 publications

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“…They are tiny, low cost, rapid, and easily mounted in either air or soil but unfortunately will not provide humidity data when condensation occurs on the chip. A very large number of these also would be necessary for spatial representation and so might be best combined with a remote sensing method [e.g., Darke and McKenna Neuman , 2008].…”

Section: Discussionmentioning

confidence: 99%

Humidity control of particle emissions in aeolian systems

Neuman

Sanderson

2008

J. Geophys. Res.

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[1] Humidity is an important control of the wind speed required to entrain particles into an air flow and is well known to vary on a global scale, as do dust emissions. This paper reports on wind tunnel experiments which quantify this control through placing a polymer capacitance sensor immediately at the bed surface. The sensor measured changes in the humidity (RH) of the pore air in real time. RH was varied between 15% and 80% and the critical wind speed determined for the release of particles to the air stream. The results strongly support earlier suggestions that fine particles are most affected in relatively dry atmospheres, particularly those which are tightly packed. An analytical model is proposed to describe this relationship which depends on determination of the matric potential from the Kelvin equation. The total contact area between particle asperities adjoined by pendular rings is represented as a power function of the number of layers of adsorbed water. The value of the exponent appears to be governed by the surface roughness of the particles and their packing arrangement. Parallel developments in colloid interface science and atomic force microscopy, relevant to industrial and pharmaceutical applications, support these conclusions in principle and will likely have an important bearing on future progress in parameterization of the proposed model.

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Section: Discussionmentioning

confidence: 99%

Humidity control of particle emissions in aeolian systems

Neuman

Sanderson

2008

J. Geophys. Res.

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“…Recently remote sensing of surface brightness has been undertaken using video imagery (McKenna Neuman and Langston, 2006; Darke and Neuman, 2008; Darke et al ., 2009). Whilst this enables surface moisture inference at a high spatial resolution and is particularly useful for long‐term, large‐scale monitoring (e.g.…”

Section: Introductionmentioning

confidence: 99%

Aeolian sand strip mobility and protodune development on a drying beach: examining surface moisture and surface roughness patterns measured by terrestrial laser scanning

Nield

Wiggs

Squirrell

2010

Earth Surf Processes Landf

117

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Ephemeral aeolian sand strips are commonplace on beaches. Their formation during high energy sand transport events often precedes the development of protodunes and their dynamics present interesting feedback mechanisms with surface moisture patterns. However, due to their temporary nature, little is known of their formation, mobility or the specifics of their interaction with beach surface characteristics. Similarly surface moisture has an important influence on sediment availability and transport in aeolian beach systems, yet it is difficult to quantify accurately due to its inherent variability over both short spatial and temporal scales. Whilst soil moisture probes and remote sensing imagery techniques can quantify large changes well, their resolution over mainly dry sand, close to the aeolian transport threshold is not ideal, particularly where moisture gradients close to the surface are large. In this study we employed a terrestrial laser scanner to monitor beach surface moisture variability during a three and a half hour period after a rain event and investigated relationships between bedform development, surface roughness and surface moisture. Our results demonstrate that as the beach surface dries, sand transport increases, with sediment erosion occurring at the wet/dry surface boundary, and deposition further downwind. This dynamic structure, dependent upon changing surface moisture characteristics, results in the formation of a rippled sand strip and ultimately a protodune. Our findings highlight dynamic mobility relationships and confirm the need to consider transient bedforms and surface moisture across a variety of scales when measuring aeolian transport in beach settings. The terrestrial laser scanner provides a suitable apparatus with which to accomplish this.

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“…The influence of soil moisture on wind erosion and fine dust emissions is of greatest relevance for aeolian processes (Cornelis and Gabriels, 2003;Darke and Neuman, 2008) and was quantified in numerous studies: critical soil moisture levels were derived for loessial sandy loam soils (Chen et al, 1996, 4%), a sandy soil (Bolte et al, 2011, 4-5%), and fine sand to clay soils (Selah and Fryrear, 1995). Funk et al (2008) described different soil moisture thresholds for fine dust emissions with sand (2-5%), silt (5-10%), clay (20%), and organic soils (25-45%).…”

Section: Introductionmentioning

confidence: 99%