Estimation of cover and crop management factor in soil erosion risk analysis by remote sensing methods

Vegetation cover is regarded as one of the most important protection precautions for controlling soil erosion and increasing quality of water reserves. Numerous articles have been published about the fact that more delicate, practical, and reliable estimations can be made through Normalized Difference Vegetation Index (NDVI), a tool of remote sensing, at the stage of calculating "cover and crop management factor (C-factor)" in Revised Universal Soil Loss Equation (RUSLE), the most widely used model in the world in the estimation of potential surface erosion. In this study, the C-factor map that belongs to the Tortum-North watershed within the district of Tortum in the province of Erzurum was attempted to be produced in GIS with the help of NDVI profile obtained from the WorldView2 satellite imagery with a spatial resolution of 50 cm and by using various C-factor equations in the literature. At the end of the study, equations with the best estimation in terms of land use types were produced with the regression models of linear for pasture, exponential for agriculture and Durigon et al. (2014) for rocky areas. The C-factor map that represents all land use/land cover types together was produced by "linear regression model" (R2=0.798). It was observed that all models used displayed statistically significant differences among themselves. These differences are attributed to steepy and heterogeneous topography and the different growth trends of the vegetation types at different elevation levels.