|VADDELLA, VENKATA - Texas A&M University|
Submitted to: Aeolian Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/8/2014
Publication Date: 9/8/2014
Citation: Sharratt, B.S., Vaddella, V. 2014. Threshold friction velocity of crusted windblown soils in the Columbia Plateau. Aeolian Research. doi: 10.1016/j.aeolia.2014.08.002.
Interpretive Summary: Wind erosion occurs when the wind velocity exceeds the threshold wind velocity of particles lying on the soil surface. Our ability to predict wind erosion is therefore dependent on estimating the threshold wind velocity of soils. Although soil crusting is an important factor affecting the threshold wind velocity, no information exists that describes the relationship between soil crusting and threshold velocity of soils in the Columbia Plateau. We found threshold wind velocity increased exponentially with crust thickness, with little or no erosion of soils having crusts >2 mm in thickness. Model developers can use the relationship developed between soil crust thickness and threshold wind velocity to improve the performance of wind erosion models in the Columbia Plateau.
Technical Abstract: Wind erosion processes are governed by soil physical properties and surface characteristics. Erosion is initiated when the friction velocity exceeds the threshold friction velocity (u*t) of soils. Although u*t is influenced by soil physical properties such as wetness and crusting, there is little information available that describes the effect of soil crusting on u*t. Knowledge of the relationship between soil crusting and u*t is required to improve our ability to predict wind erosion and PM10 (particulates less than or equal to 10 µm in diameter) emissions from crusted soils. Threshold friction velocity was assessed on five soil types commonly found across the Columbia Plateau. These soils were subject to various rainfall amounts to promote crust formation and then exposed to winds inside a wind tunnel. Emission of soil particulates and PM10 as a function of wind speed was monitored by saltation and aerosol sensors. Threshold friction velocity was determined by systematically increasing wind velocity until there was an observed increase in airborne particulate or PM10 concentration. The development of a soil crust dramatically affected u*t; u*t increased exponentially with an increase in crust thickness. Soils with a crust thickness of >2 mm appeared stable, resulting in little or no emission of particulates under the most extreme winds generated by the wind tunnel. The relationship between u*t and crust thickness will aid in simulating wind erosion of agricultural soils.