Soil Roughness Factor (SR)

This is the availability of features on the surface that act as barriers and dissipates against the erosive force of wind.

Surface roughness often shortened to roughness, is also a component of surface texture. It is quantified by the deviations in the direction of the normal vector of a real surface from its ideal form. If these deviations are large, the surface is rough; if they are small, the surface is smooth. Thus, it becomes a function of the rise and fall of land (Digital Elevation or terrain Model)

Surface roughness can also be defined by the availability of various land use classes such as vegetation cover that has a sheltering effect on soil particle against detachment and transportation by wind. For this reason, the availability of land cover data was guranteed, and was used as a proxy to surface roughness factor. Land cover classes was reclassified into five major classes i.e. water, forest, perennial croplands, sparse vegetation and bare areas to define the surface roughness as prescribed by Fryrear et al. (1998) and Swanker et al. (2018). The reclassified land classes will be assigned surface roughness values as captured in table below.

The figures represent C factor values as treclassification values for soil roughness factor derived from land use land cover.

To factor in the inverse relationship between surface roughness and wind erosion, the assigned values will be further fuzzified on a 0 to 1 scale using a reducing sigmoidal function, which assigns the highest sensitivity (1) to the bare areas and the lowest sensitivity (0) to the forested areas.