PREDICTION OF SOIL EROSION RISK USING A GIS-BASED USLE MODEL: A CASE STUDY FROM THE SUHUT WATERSHED AREA, AFYONKARAHISAR, TURKEY

Soil erosion is a serious environmental problem in the Suhut watershed which is located in the Afyonkarahisar province, Turkey. The purpose of this study is to apply Universal Soil Loss Equation (USLE) in conjunction with Geographic Information Systems (GIS) in order to estimate potential soil loss from the Suhut watershed. This will allow the identification of areas susceptible to water erosion for land management purposes, so that further soil loss can be minimized. For the USLE model, the following factors were used: rainfall-runoff erosivity (R), soil erodibility (K), slope length and steepness (LS), cover management (C) and support practice (P). The R-factor was developed from annual precipitation data, the K-factor was calculated from soil samples collected from the study area, the LS-factors were developed from a digital elevation model (DEM), and C-factor data was generated from Landsat-5 TM images. All data were integrated using GIS environment and data input, while processing, analysis, display and output tools of GIS were used. Almost half of the watershed falls within the low (69%) and slight erosion category (3%), which is mostly seen in the eastern section of the study area. The low and slight erosion risk areas are situated in flat plain and low slope areas, where soil erosion by water is not active. About 21% of the watershed area, mostly found in the western section of the watershed, is under high and severe erosion risk. The results can be used to advise local government with regard to prioritizing the areas of immediate erosion mitigation.