PSIAC Based Fuzzy Pattern Recognition Methodology for Watershed Erodibility Evaluation

Document Type : Research Paper


1 M.Sc. of Hydraulic Structures, Iran University of Science and Technology

2 Prof., Civil Eng. Dept., Iran University of Science and Technology

3 Associate Prof., Civil and Environmental Eng. Dept., Amirkabir University of Technology


Various experimental and mathematical methods have been developed to assess the soil erosion potential and sediment yield. Among theses methods, the PSIAC method is one of the well known parametric and index methods. The uncertainty about recognition and decision of erodibility is an ambiguous uncertainty or on the other hand is a fuzzy problem. Furthermore, in PSIAC pattern, the space between input variables is divided into explicit and fixed sets so that the PSIAC indices of the input variables are not continuous. Hence, any variation of input parameter in this space and its effect will not be appeared at the final output PSIAC index. Due to the foregoing matters, in this study a fuzzy recognition approach is presented on the basis of PSIAC parameters. This method has a continuous form and is sensitive to the parameters variation in the discretized schemes. From conceptual point of view, the mentioned variations can be considered in the model output by fuzzy method. As a case study, both PSIAC and fuzzy pattern recognition were utilized to find the erodibility potential of Daryanchai watershed. The obtained results show, although the main trend of the erodibility potential in  both methods is similar, some differences can be seen between the results of the two methods. These differences can be related to the computation schemes of the methods and continuous computational space of fuzzy approach in comparison with the PSIAC method.


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