Rectangular Open Channel Calculation

Compute velocity and flow for a rectangular open channel (non-full flow).

Inputs

Channel width W m

Water depth H m

Roughness coefficient n —

Hydraulic gradient i —

Result

Velocity v

—

m/s

Flow rate Q

—

m³/s

Flow area A

—

m²

Wetted perimeter X

—

Hydraulic radius R

—

Q = A·v, v = (R^(2/3)·i^(1/2))/n, A = W·H, X = W+2H, R = A/X.