ABOUT THE THRESHHOLD WIND VELOCITY AT QUANTITATIVE ASSESSMENT OF WIND EROSION INTENSITY

Abstract

Short analysis of present empirical dependences introduced for wind soil erosion calculation and generalized empirical model developed by V.M. Gendugov and G.P. Glazunov for the purpose of their further approbation and adaptation for conditions of Belarusian Polesie, where wind erosion is the most intensive and inflict the largest damage to soils, is performed in the article. The main factor influencing the carrying out of soil particles by air stream - friction shear stress invoked by wind on soil surface, is considered. Test of hypothesis about dependence form between friction shear stress and wind velocity at approximation of published experimental data received by V.M. Gendugov and G.P. Glazunov in the wind tunnel is realized. For the first time has established, that wind velocity minus value called by us “threshold wind velocity” having clear physical sense: only during obtaining threshold wind velocity friction shear stress appears on soil surface (and begins to grow with further wind velocity growth), should be used as argument of calculated quadratic dependence. Has determined, that transference and removal of soil particles from surface during obtaining threshold wind velocity are not yet may be observed, but friction shear stress appears and preconditions of wind soil erosion occur. Experimental data statistical analysis has shown, that strength of links of derived dependence higher than of earlier suggested wind soil erosion models with use of cube and squared wind velocity, what authenticates about the competence of the proposed parameter introduction. Substantiation of numerical value of threshold wind velocity is realized, which is permanent for any soil surface with any roughness, size and particles composition density, and is about 4 m/s.