Abstract: In this study the basic theories of development of the meanders in rivers are described and categorised and the role of sediment balance on the morphological changes in these types of rivers is investigated using the fuzzy method. A supervised clustering fuzzy algorithm was applied to determine the sediment balance in a meandering river. The capability of the fuzzy method in recognition of the sediment transport trend was first checked using two analytical problems and the approved algorithm was then applied to recognise the trend of sediment transport and balance for Karoon River, the largest river in Iran. The predicted results obtained from the fuzzy model were compared with the sediment balance results for three sediment measuring sites along a 140 km reach of Karoon. This research has shown that the sediment balance along the research area was negative before construction of Karoon dam and as a result the bank erosion was continued at that period and after dam operation the sediment transport capacity of the river has decreased and now the river is in sedimentation conditions. The result of this research study was also that sedimentation occurs at the outer banks for this situation and as a result the river sinuosity index decreased and radius curvature of river increased.