PREDICTION AND MITIGATION OF RIVER BED VARIATION IN A MEANDERING CHANNEL WITH ALTERNATING BARS

In most rivers in Japan, tolerable degradation occurs because of the sediment trap by the reservoirs upstream, and the severe gravel mining which was done during the period of rapid increase in economy.As a result, disasters during flood have been increased due to local scouring around river dykes and other structures.Therefore, it is required to predict and mitigate the river bed variation not only for it' s mean value but also for local scouring, especially for meander channel.The authors investigate experimentally the channel deformation, bed variation and velocity distribution in an experimental meandering channel with flood plain of alternating bars, which was constructed by modeling the channel of the Naka river.More over, the mitigation of local scouring by groins was investigated.An analytical approach was also presented for predicting the river bed variation and for estimating the effect of groins for the mitigation of local scouring.The analitical approach was found to be applicable for the experiment.