Numerical simulation of the natural processes of river meandering over realistic time scales

In this study, the numerical flow and sediment-transport model including sub-models for bank erosion considering slump block, land accretion and cut-offs, is developed. And its validity has been investigated by calculating the meandering evolution process. It has been conducted under an unsteady discharge condition using experimental scale flume. Result shows that the bank erosion expands the channel width at along outer bend. On the other hand the land accretion narrows it along inner bend. Due to repetition of big and small discharge both phenomena have been repeated, and a meandering shape is developed and migrate from upstream to downstream. Further, the channel shape is changed drastically at the time when bank lines are crossed so called as cutoff. Results of this study indicate that a variation of discharge is key role to create complex a meandering shape which can be seen in a natural river.