Mannings

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.
Reference 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.

I want to find the of my

Cross Section Input

Bottom Width m
Rectangular channel diagram

Cross Section Input

Bottom Width m
Left Side Slope (H:V) m/m
Right Side Slope (H:V) m/m
Trapeziodal channel diagram

Cross Section Input

Bottom Angle °
Triangular channel diagram

Cross Section Input

Pipe Diameter m
Circular channel diagram

Cross Section Input

Area
Wetted Perimeter m

Other Inputs

Flow Depth m
Channel Slope m/m
Manning's n

Outputs

Flow Velocity m/s
Flow Discharge m³/s

Inputs

Flow Depth m
Manning's n
Flow Discharge m³/s

Outputs

Channel Slope m/m

Inputs

Flow Depth m
Channel Slope m/m
Flow Discharge m³/s

Outputs

Manning's n

Other Inputs

Channel Slope m/m
Manning's n
Flow Discharge m³/s

Outputs

Normal Depth m
Flow Velocity m/s

Sorry not possible. Please try another combination.