Assessment of Spatial variabilities of Soil Erodibility by Wind on Margial lands of the Lake Urmia

Wind erosion is one of the most important processes of land degradation and desertification in arid, and semi-arid areas. Due to lowering of Urmia Lake’s water level, large bare land was created, which makes it crucial to assess their susceptibility to wind erosion. This research was carried on according to the geomorphological mapping unit (facies), field sampling, and granulometric measurements, as well as threshold wind velocity analysis. Results showed that the facies including saline and puffy lands (19%), inselberg island (13.5%), salt crust dry-river (12.8%), and abandoned lands (10.7%) have been the most frequent land surfaces over the study area, respectively. Granulometric studies showed that the average particle diameter, sorting, and skewness are 870 μ, 2.91 and -0.15, respectively. Assessment of threshold wind velocity (Vt) according to the Velikanov formula, showed that the highest and lowest value was 18.83 and 8.3 Knots, and the weighted average on the geomorphological facies was estimated 11 knots. The most value of erodibility factor is estimated for the puffy and salty land surface. Although the wind erodibility of the study area is noteworthy, the wind erosion rate cannot be severe due to natural conditions, such as climate and the presence of vegetation. Zonation of soil erodibility showed that the southeastern parts of the Islamic Island and northwest littoral area of Lake Urmia were the most susceptible regions to wind erosion. Evaluation of sand drift potential showed that the highest potential was in Tabriz (DP= 232, UDI= 0.05), Khoi (DP= 130, UDI= 0.49) and Urmia (DP= 63, UDI= 0.59) stations, respectively. Finally, due to lack of sand sources and wind’s energy, the western and northwestern part of the Lake Urmia have more capability for sand dunes formation and wind erosion. However, for salt emission and effecting of the surrounding, lands more research is needed to find out the susceptible area to salt weathering.