Developing a soil erodibility map across Mongolia

Wind erosion and dust emissions are land surface processes that characterize drylands globally. Wind erosion depends on the relationship between erosivity and erodibility factors. Soil erodibility measures the relative potential for soils to be eroded by wind. In this study, soil erodibility was estimated from soil and vegetation data. Global soil texture data, a global soil database and a Normalized Difference Vegetation Index (NDVI) dataset were used to evaluate soil erodibility over Mongolia in terms of two parameters: wind erodible fraction of soil (a measure of erodibility related to soil properties) and threshold friction velocity. Threshold friction velocity was estimated using the frontal area of the roughness element that was calculated using NDVI-derived vegetation cover. A novel integrated soil erodibility map over Mongolia was developed using the two erodibility parameters and a soil classification map. The estimated wind erodible fraction of soil showed that erodibility is higher in the desert and the desert steppe regions. The estimated threshold friction velocity exhibited also a regional pattern. The threshold friction velocity was lower in the desert and desert steppe regions and higher in the forest area. The integrated soil erodibility map revealed widespread areas of high erodibility from the desert and desert steppe regions in the south to the sandy areas in the west. Low-erodibility areas extended from western to northern Mongolia, while medium-erodibility areas mostly covered the dry steppe regions and the desert steppe in the west. The integrated map will provide a useful climatological basis for studying dust emission processes and for developing practical dust risk assessment and early warning system applications.