Rectangular Culvert (Full Flow)

Full-flow rectangular box culvert. A = W·H/10⁶, ρ = (2W+2H)/10³, R = A/ρ, v = R^(2/3)·√i/n, Q = v·A.

Inputs

Channel width W mm

Channel height H mm

Hydraulic gradient i —

Roughness n —

Result

Velocity v

—

m/s

Flow rate Q

—

m³/s

Flow area A

—

m²

Wetted perimeter ρ

—

Hydraulic radius R

—

A = W·H/10⁶, ρ = (2W + 2H)/10³, R = A/ρ. Manning velocity v = R^(2/3)·√i/n with fixed n = 0.013; discharge Q = v·A. W and H are entered in mm.