The
Manning formula is also known as the
Gauckler–Manning formula, or
Gauckler–Manning–Strickler formula in Europe. In the United States, in practice, it is very frequently called simply
Manning's Equation. The
Manning formula is an
empirical formula estimating the average velocity of a liquid flowing in a conduit that does not completely enclose the liquid, i.e.,
open channel flow. All flow in so-called open channels is driven by
gravity. It was first presented by the French engineer Philippe Gauckler in 1867, and later re-developed by the
Irish engineer Robert Manning in 1890.