Work out manning equation flow instantly with clear inputs, formula shown and shareable results.
Manning's equation gives open-channel velocity as (1/n) R^(2/3) S^(1/2). With a hydraulic radius of 1.1 m, a slope of 0.002 and n = 0.035 for a natural channel, velocity is 1.36 m/s and discharge 11.4 m3/s. The Froude number below one confirms subcritical flow, where depth controls from downstream.
Manning velocity
v = (1/n) x R^(2/3) x S^(1/2)
Discharge
Q = A x v
About 0.012 for concrete, 0.025 for a clean earth channel, 0.035 for natural streams and 0.07 or more for heavily vegetated floodplains.
Below one the flow is subcritical and tranquil; above one it is supercritical and fast, and a hydraulic jump forms where the two meet.