Stormwater Drainage

Flow Calculator

Manning's Equation Analysis

Calculate flow rates and hydraulic properties using Manning's equation for open channel flow in trench drains.

1
Channel Properties

2
Flow Rate Results

Cubic Feet/Second

0.00

CFS

Gallons/Minute

0.00

GPM

Liters/Second

0.00

L/s

Cubic Meters/Second

0.0000

m³/s

Flow Characteristics

Velocity

0.00

m/s

Froude Number

0.00

Fr

Flow Regime

subcritical

Fr < 1: Slower, deeper flow controlled by downstream conditions.

Learn more about flow regimes →

About This Calculator

This calculator uses Manning's equation to determine flow rates and hydraulic properties for open channel flow. Results consider channel geometry, slope, and surface roughness.

Q = (1/n) × A × R^(2/3) × S^(1/2)

  • Q = Flow rate
  • n = Manning's roughness coefficient
  • A = Cross-sectional area
  • R = Hydraulic radius
  • S = Channel slope