1949 年 58 巻 6-7 号 p. 198-203
Mean velocity of the river flow is proportional to the depth of the water and the slope of the water surface.
It is said that the velocity is greater at the upper course with steeper slope than at the lower course with gentler slope in the normal i.w water level.
In case of the good of the river Kitakami in 1948, however, the author examined the velocity of the transmission of the flood wave, finding that it is slower at the steeper slope in mountains and canyons than that of the lower flood plains. The reason for the decrease of the velocity in the flood flow in mountains has been explained as the result of the increase in the content of gravels and sands in the flood water.