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National Science Foundation (USA) 2004

The Effect of Atmospheric Humidity on the Susceptibility of Dry Soils to Wind Erosion

Humidity Soils Wind Erosion


Titre : The Effect of Atmospheric Humidity on the Susceptibility of Dry Soils to Wind Erosion

Organismes NSF : Division Of Earth Sciences (EAR)

Durée : September 1, 2004 - August 18, 2004

Wind erosion is a widespread process in arid and semi-arid regions, and contributes to loss of soil fertility, alteration of atmospheric radiation, and air pollution, with important impacts on global and regional climates, agriculture, and human health. Erosion occurs when wind speed exceeds a certain threshold, the value of which depends on a number of factors, including surface soil moisture. It is argued that in arid regions, under air-dry conditions, variations in surface soil moisture can be significantly affected by changes in atmospheric humidity, with an important effect on wind erosion potential, and that this effect is not currently well understood or quantified.
It is argued that in fact the effect of soil moisture on susceptibility to wind erosion is opposite in the air-dry range of soil moistures to its effect in the capillary range, i.e., that the drier an air-dry soil is, the less susceptible it is to wind erosion. The proposed research will test this hypothesis and quantify the effect by analysis of several important agricultural soils of the United States, which are strongly subject to wind erosion, as well as well-sorted, clean sands, which will function as "reference" soils. In particular, the project will (1) investigate the dependence of surface soil moisture (i.e., in a few grain layer) on air humidity and temperature ; (2) determine the relationship between threshold wind velocity, and near surface air humidity and temperature by means of a number of wind tunnel tests, and (3) interpret the results in terms of a theoretical framework that will account for the dependence of interparticle forces on absorbed layer bonding on interparticle forces and soil matric potential. This approach will provide a theoretical equation expressing threshold wind velocity as a function of air humidity for air-dry soils. The parameters of this equation will be determined through the results of the wind tunnel experiments. The assessment of the type of dependence existing between soil erosion potential and surface moisture content is crucially important to the understanding and modeling of wind erosion and dust emission from dryland landscapes.

Partenaires : Thomas Over tmover (Principal Investigator)

Financement : $73,581.00

Présentation (National Science Foundation)

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