Basic formula for calculating the discharge through a weir is:

Correct option is A

• Q represents the discharge or flow rate (in cubic meters per second).

• C is the discharge coefficient, which depends on the type of weir and the flow conditions.

• L is the length of the weir (in meters).

• H is the head, or the height of the water above the crest of the weir (in meters).

• m is a constant that depends on the type of weir and the flow characteristics, typically 1.5 for sharp-crested weirs.​