Okayama has many three-sided waterways and many people have lost their lives there, so the danger of three-sided waterways was investigated through flow velocity distribution. In three-sided waterways, even if the average water level drops to a certain extent, there is little difference in average flow velocity, whereas in rivers there is a tendency for differences to be more pronounced than in three-sided waterways. In three-sided waterways, the distance from the point showing the highest flow velocity to both banks is short, whereas in rivers the opposite tendency is seen. When teaching about flowing water in relation to natural disasters, it is necessary to consider improvements in the presentation of data and model experiments.
