Open Channel Section Design

Trapezoidal open channel (sewage/rainwater), non-full flow, n=0.025. Section design and earthwork volume.

No. Start End Length L (m) Design Qs (m³/s) Channel H (m) Water depth h (m) Bottom width b (m) Side slope a Slope i (‰) Invert ↑ (m) Top width (m) Earthwork (m³) v (m/s) Capacity Q (m³/s) ΔH (m) Invert ↓ (m) ΔQ
Max velocity
m/s
Design flow ΣQs
m³/s
Capacity ΣQ
m³/s
Earthwork ΣV

Trapezoid flow area A = b·h + h²/a. Manning velocity v = (A/(b+2·(h²+(h²/a)²)))^(2/3)·√(i/1000)/n with n=0.025; capacity Q = A·v. Top width = b + 2·H/a; earthwork = (b·H + H²/a)·L. Capacity must be no less than design flow.