OPEN CHANNEL CALCULATOR
The Manning's equation is used to analyse open channel flows. For pressured pipes see the Darcy-Weisbach calculator.
- A = Cross sectional area of pipe, culvert or channel.
- P = Wetted perimeter; the length of the circumference in contact with water.
- S = Slope of the bottom in the direction of flow.
- Q = Discharge (flow rate).
- V = Average velocity across the cross section.
- n = Manning's n; roughness co-efficient.
Manning, R. (1891). "On the flow of water in open channels and pipes". Transactions of the Institution of Civil Engineers of Ireland. 20: 161–207.