1991 年 11 巻 Supplement1 号 p. 161-164
A pair of aerial photographs of flood flow of Ishikari River were analysed by picture processing to obtain two-dimensional distribution of velocity vectors of the flood surface. Streamline patterns, vorticity and divergence were calculated using the obtained velocity data and the structure of the vortices and its relation with river sedimentation were elucidated.
Strong upwellings (boils) in the vortices and strong downflows around the edge of the vortices were shown to be the main cause of the formation of the core of scroll bars.