The Manning's n is a coefficient which represents the roughness or friction applied to the flow by the channel. Manning's n-values are often selected from tables, but can be back calculated from field measurements.

How is Manning's roughness coefficient calculated?

where K=conveyance of the channel, in cubic feet per second, A = cross-sectional area of channel, in square feet, R = hydraulic radius, in feet, and n= Manning's roughness coefficient. The term K, known as the conveyance of the channel section, is a measure of the carrying capacity of the channel section.

What does roughness coefficient mean?

A value used in Manning's formula to determine energy losses of flowing water due to pipe or channel wall roughness.