Gully erosion and its complex and variable characteristics have led to challenging and many problems for creation of erosion maps with the most commonly used methods of satellite imagery analysis. The fuzzy algorithm-based object-based image analysis (OBIA) method is one of the most effective methods for classifying satellite imagery, which aims to integrate the spectral satellite imagery and provides the necessary facilities for the use of environmental and spatial information as well as a geometric feature of land surface phenomena. The purpose of this study was to apply and evaluate the implementation of different classification algorithms and fuzzy functions membership detecting and mapping of gully erosion. For this purpose, satellite images of Sentinel-2 were employed and accordingly the soil erosion map of Lighvan watershed was developed within the semi-automated approach by applying fuzzy-OBIA features and techniques. The obtained results from the accuracy assessment of the methods indicated that the accuracy of gully maps obtained by fuzzy- OBIA features including: length/width, asymmetry, density, and shape index algorithms with the respective kappa coefficient of 0.78, 0.91, 0.85, and 0.89 is higher than other algorithms. Also, the results obtained from the study of the degree of membership of fuzzy functions indicate the high role of this factor in the accuracy of the results, so that the highest classification accuracy (kappa coefficient greater than 0.91) was related to the length/width algorithm, in which the fuzzy functions B, D, H and L with the highest degree of membership (0.685, 1, 0.972 and 1, respectively) were employed. Results of current research are great of important for decision makers and authorities by means of providing detailed information regarding the soil erosion in the study area as well as GIS sciences society for applying and introducing the most efficient methods and techniques.
