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Research indicates that soil movement commences when wind speeds surpass a critical threshold and the rate of erosion aligns with the cube of the friction velocity. Friction velocity, denoted as U ∗ {\textstyle U_{*}} , is a meteorological term for wind speed at the Earth's surface and can be quantified using the equation:
The stereographic projection, also known as the planisphere projection or the azimuthal conformal projection, is a conformal map projection whose use dates back to antiquity. Like the orthographic projection and gnomonic projection , the stereographic projection is an azimuthal projection , and when on a sphere, also a perspective projection .
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As the name indicates, the UPS system uses a stereographic projection. Specifically, the projection used in the system is a secant version based on an elliptical model of the earth. The scale factor at each pole is adjusted to 0.994 so that the latitude of true scale is 81.11451786859362545° (about 81° 06' 52.3") North and South.
The runoff curve number is based on the area's hydrologic soil group, land use, treatment and hydrologic condition. References, such as from USDA [1] indicate the runoff curve numbers for characteristic land cover descriptions and a hydrologic soil group. The runoff equation is:
Tree, shrubs and ground-cover are effective perimeter treatment for soil erosion prevention, by impeding surface flows. A special form of this perimeter or inter-row treatment is the use of a "grass way" that both channels and dissipates runoff through surface friction, impeding surface runoff and encouraging infiltration of the slowed surface ...
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[34] [35] There is growing evidence that tillage erosion is a major soil erosion process in agricultural lands, surpassing water and wind erosion in many fields all around the world, especially on sloping and hilly lands [36] [37] [38] A signature spatial pattern of soil erosion shown in many water erosion handbooks and pamphlets, the eroded ...