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mLine 1:
Line 1: − + − *''L'' is the length of perforated pipe (m)+ − − + − +
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Orifices are simply holes which restrict the flow of water. They may be used at the bottom end of an LID practice to add some [[flow control]].
Orifices are simply holes which restrict the flow of water. They may be used at the bottom end of an LID practice to add some [[flow control]]:
<math>Q= B\times C_{d}\times A_{o}\sqrt{2\cdot g\cdot h}</math>
<math>Q= B\times C_{d}\times A_{o}\sqrt{2\cdot g\cdot h}</math>
{{Plainlist|1=Where:
{{Plainlist|1=Where:
*''B'' is the clogging factor (between 0.5 (for matured installation) and 1 (for a new perfectly performing orifice)),
*''B'' is the clogging factor (between 0.5 (for matured installation) and 1 (for a new perfectly performing BMP)),
*''C<sub>d</sub>'' is the coefficient of discharge (usually 0.61 for a plate, or 0.8 for a pipe),
*''C<sub>d</sub>'' is the coefficient of discharge (usually 0.61 for a plate, or 0.8 for a pipe),
*''A<sub>o</sub>'' is the area of the orifice (m<sup>2</sup>/m),
*''A<sub>o</sub>'' is the area of the orifice (m<sup>2</sup>),
*''g'' is acceleration due to gravity = 9.81 m/s<sup>2</sup>, and
*''g'' is acceleration due to gravity = 9.81 m/s<sup>2</sup>, and
*''h'' is the head of water over the centre of the orifice.
*''h'' is the head of water over the centre of the orifice (m).
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