Threshold Velocity as Related to soil Physical and Chemical Properties in Iranian Central plain (Case study:yazd.;.Ardakan Plain)

Wind erosion is one of the main and important natural phenomena in arid and hyper-arid regions.
Wind erosion is due to blow of erosive wind on dry, soft and erodible soil. Soil particles are
transported in three mechanisms: creeping, saltation and suspension , Wind .erosion causes serious damage to the environment. In this research,the investigators try to recognize soil physical and chemical properties as related to threshold velocity. Threshold velocity was measured in a natural soil surface condition by a portable wind tunnel (wind erosion meter). soil,samples were air dried .Desert pavement, mean diameter of soil particles, electrical conductivity, sodium adsorption rate, gypsum, organic matter 'and lime were determined. The relationship between desert pavement and mean diameter of soil particles is more significant than the relationship of other factors to threshold velocity.
The mathematical function detected is presented in two models, on the basis of main .physical
properties and main physico-chemical properties.