Soil Erosion Risk Assessment in the Sincanli Sub-Watershed of the Akarcay Basin (Afyonkarahisar, Turkey) Using the Universal Soil Loss Equation (USLE)

This paper contains research in which the authors applied the Universal Soil Loss Equation (USLE), Geographical Information Systems (GIS), and remote sensing to the mapping of the soil erosion risk in the Sincanli sub-watershed area of the Akarcay Basin, Afyonkarahisar, Turkey. The rainfall-runoff erosivity factor (R) was developed from annual precipitation data and previous studies, soil map and soil survey data was used to develop the soil erodibility factor (K), and a digital elevation model image was used to generate the topographic factor (LS). The cover-management factor (C) was developed based on vegetation, shade, and soil fraction images derived from spectral mixture analysis of a Landsat Thematic Mapper image. A soil erosion risk map with four classes (low, slight, moderate, and high) was produced based on the simplified USLE within the GIS environment. The low erosion category is very common (83%), while, to only a limited extent, the watershed falls within the slight erosion risk category (2%), mostly seen in the central section of the study area. The low and slight erosion risk areas are situated in the flat plain and low slope areas where there is no soil erosion by water. Moderate risk of erosion occurs in a small area (4%) of the watershed, but about 11% of the watershed is under high erosion risk, found mostly in the south-western, southern and eastern, and partly in the north-eastern sections of the watershed where there are mountains consisting of resistant rocks such as limestone, tuff-agglomerate, andesite, and trachyte. It is believed that the results of this study can be used to advise the local authorities/government in prioritizing the areas of immediate erosion mitigation. This research implies that GIS and remote sensing provide promising tools for evaluating and mapping soil erosion risks in the Sincanli area.