Wind erosion is considered as one of the main processes of land degradation in different parts of the world, including Iran. The best and most effective way to control wind erosion is to cover the surface of the earth by natural vegetation, and the more vegetation, the more protection. The basis of the biological and mechanical soil conservation, in particular, the construction of a windbreak, is the wind erosion threshold calculation. When the wind speed is less than the wind erosion threshold, there is no need to wind erosion control. In this study, the Envi-met Headquarter model was used to design a biological windbreak, and wind tunnel test was used to determine the wind erosion threshold. Based on the simulation results, in the pattern designed for the Prosopis juliflora species, although the wind speed decreases in the front of the windbreak, it returns to the initial speed in a longer distance behind the windbreak. Therefore, the designed windbreak for the this species will be able to reduce the wind speed to a far distance while in the designed windbreak for the Haloxylon aphyllum species the wind is returned to the initial speed in a shorter distance. According to the results, it seems that the designed windbreak for the Prosopis juliflora species, protect the longer distance behind the windbreak and more effectively reduce the wind speed and can be proposed as a suitable windbreak for the study area. Of course, more studies are needed in this field and all aspects of the matter, including economic issues, groundwater level, etc., should be considered. Also, it can be concluded that the wind speed reduction is directly related to the height of the windbreak, and the higher the windbreak, the more wind speed reduction and less wind erosion rate.
