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A THEORETICAL AND WIND TUNNEL INVESTIGATION OF THE EFFECT OF CAPILLARY WATER ON THE ENTRAINMENT OF SEDIMENT BY WIND

A THEORETICAL AND WIND TUNNEL INVESTIGATION OF THE EFFECT OF CAPILLARY WATER ON THE ENTRAINMENT... <jats:p> A theoretical model of the effect of small amounts of water on the threshold shear velocity of sand grains has been tested in wind-tunnel studies. The model is based upon the capillary forces developed at interparticle contacts surrounded by isolated wedges of water. These forces (F<jats:sub>c</jats:sub>) are inversely proportional to moisture tension (P) and directly proportional to the geometric properties of the contacts (G). Given[Formula: see text]the cohesion of the material decreases with increasing moisture tension and particle angularity. The incorporation of this capillary force model into Bagnold's threshold model for dry particles gave a general relation which indicated that the threshold shear velocity of wet particles increases as the square root of the inverse of moisture tension. Laboratory measurement of the soil moisture characteristic curve of any sand therefore provides a simple, though indirect indication, of its susceptibility to entrainment by wind under low moisture conditions. Most sands appear to be exceedingly resistant to wind erosion at moisture tensions below 10 MPa or at gravimetric moisture contents above approximately 0.2%. Further work is needed to determine if this potentially practical relationship also applies to more complex agricultural soils. Key words: Aeolian, moisture tension, threshold shear velocity </jats:p> http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Canadian Journal of Soil Science CrossRef

A THEORETICAL AND WIND TUNNEL INVESTIGATION OF THE EFFECT OF CAPILLARY WATER ON THE ENTRAINMENT OF SEDIMENT BY WIND

Canadian Journal of Soil Science , Volume 69 (1): 79-96 – Feb 1, 1989

A THEORETICAL AND WIND TUNNEL INVESTIGATION OF THE EFFECT OF CAPILLARY WATER ON THE ENTRAINMENT OF SEDIMENT BY WIND


Abstract

<jats:p> A theoretical model of the effect of small amounts of water on the threshold shear velocity of sand grains has been tested in wind-tunnel studies. The model is based upon the capillary forces developed at interparticle contacts surrounded by isolated wedges of water. These forces (F<jats:sub>c</jats:sub>) are inversely proportional to moisture tension (P) and directly proportional to the geometric properties of the contacts (G). Given[Formula: see text]the cohesion of the material decreases with increasing moisture tension and particle angularity. The incorporation of this capillary force model into Bagnold's threshold model for dry particles gave a general relation which indicated that the threshold shear velocity of wet particles increases as the square root of the inverse of moisture tension. Laboratory measurement of the soil moisture characteristic curve of any sand therefore provides a simple, though indirect indication, of its susceptibility to entrainment by wind under low moisture conditions. Most sands appear to be exceedingly resistant to wind erosion at moisture tensions below 10 MPa or at gravimetric moisture contents above approximately 0.2%. Further work is needed to determine if this potentially practical relationship also applies to more complex agricultural soils. Key words: Aeolian, moisture tension, threshold shear velocity </jats:p>

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Publisher
CrossRef
ISSN
0008-4271
DOI
10.4141/cjss89-008
Publisher site
See Article on Publisher Site

Abstract

<jats:p> A theoretical model of the effect of small amounts of water on the threshold shear velocity of sand grains has been tested in wind-tunnel studies. The model is based upon the capillary forces developed at interparticle contacts surrounded by isolated wedges of water. These forces (F<jats:sub>c</jats:sub>) are inversely proportional to moisture tension (P) and directly proportional to the geometric properties of the contacts (G). Given[Formula: see text]the cohesion of the material decreases with increasing moisture tension and particle angularity. The incorporation of this capillary force model into Bagnold's threshold model for dry particles gave a general relation which indicated that the threshold shear velocity of wet particles increases as the square root of the inverse of moisture tension. Laboratory measurement of the soil moisture characteristic curve of any sand therefore provides a simple, though indirect indication, of its susceptibility to entrainment by wind under low moisture conditions. Most sands appear to be exceedingly resistant to wind erosion at moisture tensions below 10 MPa or at gravimetric moisture contents above approximately 0.2%. Further work is needed to determine if this potentially practical relationship also applies to more complex agricultural soils. Key words: Aeolian, moisture tension, threshold shear velocity </jats:p>

Journal

Canadian Journal of Soil ScienceCrossRef

Published: Feb 1, 1989

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