m
m
m
m3/s

## Formula

q = Cd × b × h2 × (2g (h1 - h2)) 1/2

Where,
q = Water Flow Rate
Cd = Discharge Constant
b = Width of the Weir
g = Gravity (9.81 m/s2)

Broad Crested Weir refers to the flow measurement and regulation of water depth in rivers, canals and other natural open channels. Broad Crested Weirs are a robust structure used to measure the full width of the channel. A broad crested weir is normally a flat topped object which obstructs and extends across the entire channel.

An overflow structure on which the nappe is supported for an appreciable length in the direction of flow is called as broad crested weir. It is a flat-crested structure, with a long crest compared to the flow thickness of water in canals and rivers.

Example:
Calculate the Broad Crested Weir for the given details.
Width of the Weir (b) = 5 m
Head 1 on the Weir (h1) = 3 m
Head 2 on the Weir (h2) = 1 m
Discharge Constant (Cd) = 10

Solution:
Apply Formula:
q = Cd × b × h2 × (2g (h1 - h2)) 1/2
Water Flow Rate (q) = 313.20919526731655 m3/s