River bank failure causes a heavy disaster. Many experiments had been conducted. Full-scale hydraulic experiment is very few, because of it has a limit to conduct in terms of space and budget. Therefore, many experiments were conducted in small scale and they need to be compared with the actual phenomenon. The large scale hydraulic experiment on river bank failure was conducted at Chiyoda experiment flume in 2008. We conducted small scale experiments on river bank failure and examined the reproducibility of the small scale experiments by comparison with the Chiyoda experiment. Fine-grained soil strongly influences the widening process of bank failure. In order to reproduce the results of experiment at Chiyoda experimental flume on dike failure, it is necessary to remove the fine material from the material of scaled dikes. And it is found that the time scale of widening process of bank failure follows the Froude similarity law.
