applicationThis study reports the resultus of velocity measurements among super dikes in River Chikuma. Two large vortices contribute to flowing in, settling and heaping of suspended particles. The uppside vortex of the impermeable super dike has a characteristic life cycle. It has a negative correlation with fluctuation of a water level. In time of flood, streamwise vortices released from lowerside of the impermeable super dike rise and flush humus mud on a river bed.departmental bulletin pape