In natural river, river-bed change is greatly influenced by the various factors such as river improvement, change of watershed land use, construction of dam and reservoir, gravel mining, and so on. The knowledge about river-bed change in the river is essential in the river modification, wetlands plan, and maintaining stable alluvial rivers. In this study, river-bed change in the future was predicted by investigating river channel characteristics which play dominant role in the formation of channel and based on the numerical model through river survey and the grain size analysis. The Proposed investigation and model was applied to the Geum river and the Miho stream which have been experienced river degradation due to river aggregate dredging and now seams to be stable. The result of potential river-bed change which was estimated by investigating channel characteristic including slope of channel, friction velocity, and so on is similar to that which was estimated based on the numerical model. It was found that the Geum river and the Miho stream will be stable. In the future, if considering the characteristics of river channel which is estimated by the river-bed scour, sediment, and so on, it is possible that river improvement and wetland restoration plan are established stably and naturally.