1.
The basic influence exerted by hydraulic grade, and, as a consequence, Froude number, on the value of the coefficient of hydraulic resistance is disclosed; this is reflected by formulas (16) and (18), and has found confirmation in field investigations [3], and in Zegzhda's experiments.
2.
In the design of canals, the coefficient of hydraulic resistance should be determined by calculation as a function of the grade and dimensions of the flow, and not assigned as a function of the frequency with which the surface of the channel is treated.