Segmented Weir Flow Equation

Simple Weir Flow Calculator
Irregular, Variable Depth Segmented Weir Flow Calculator

The equation for flow over a weir is


where (in US units)

Q = flow in cfs
Cw = weir coefficient (about 2.5 to 3 for a broad-crested weir)
L = length of weir in feet
H = height of ponded water above lip of weir in feet

The equation for a sloped segment of an irregular weir is


My online calculators for weirs are located at

The original document is available at