Power formula for open-channel flow resistance

This paper evaluates various power formulas for flow resistance in open channels. Unlike the logarithmic resistance equation that can be theoretically derived either from Prandtl's mixing-length hypothesis or von Karman's similarity hypothesis, the power formula has long had an appearance of empiricism. Nevertheless, the simplicity in the form of the power formula has made it popular among the many possible forms of flow resistance formulas. This paper reexamines the concept and rationale of the power formulation, thereby addressing some critical issues in the modeling of flow resistance.