Abstract
There is a flood terrace formed by the flood in 1986 off the Abukuma River mouth. On the terrace, a channel develops year by year, which has an important effect on the sandbarrier development by refracting waves. The cause of the channel development is estimated to be runoffs of the river but the buoyancy effect of seawater is against the erosion. As the first step to study the channel formation, we have searched the condition that the fresh water erode the seawater around the sandbarrier, expecting the effect of wake from the barrier. We get Ri≤0.5 for the erosion from the hydraulic experiments. Then we apply the result to the Abukuma River mouth.
