Parametrization of the increase of the aeolian erosion threshold wind friction velocity due to soil moisture for arid and semi-arid areas

[摘要] Large-scale simulation of the soil-deriveddust emission in semi-arid regions needs to account for the influence of thesoil moisture on the wind erosion threshold. Soil water retention consists ofmolecular adsorption on the soil grain surface and capillary forces between thegrain. Interparticle capillary forces (characterized by the moisture tension)are the main factor responsible for the increase of the wind erosion thresholdobserved when the soil moisture increases. When the soil moisture content isclose to but smaller than the maximum amount of adsorbed water, w'(depending on the soil texture), these capillary forces are considered as notstrong enough to significantly increase the erosion threshold. An expression ofthe moisture tension as a function of soil moisture and w' is derivedfrom retention curves. From this expression, a parametrization of the ratio ofthe wet to dry erosion thresholds has been developed as a function of soilmoisture and soil texture. The coefficients of this parametrization have beendetermined by using experimental data from the literature. An empiricalrelationship between w' and soil clay content has been established. Theerosion threshold ratios simulated for different soil textures were found to bein good agreement with the experimental data.

Key words. Atmospheric composition and structure(Aerosols and particles) · Hydrology (soil moisture)

[学科分类] 地球科学(综合)