Flow through an orifice

$Q=B\times C_{d}\times A_{o}{\sqrt {2\cdot g\cdot h}}$

Where:

• L is the length of perforated pipe (m)
• B is the clogging factor (between 0.5 (for matured installation) and 1 (for a new perfectly performing BMP)),
• C_d is the coefficient of discharge (usually 0.61 for a plate, or 0.8 for a pipe),
• A_o is the area of the orifice (m²/m),
• g is acceleration due to gravity = 9.81 m/s², and
• h is the head of water over the centre of the orifice.

See also

• Flow through perforated pipe

Best management practice. State of the art methods or techniques used to manage the quantity and improve the quality of wet weather flow. BMPs include: source, conveyance and end-of-pipe controls.