# Difference between revisions of "Weirs"

From LID SWM Planning and Design Guide

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<math>Q=\frac{2}{3}C_{d}\cdot L\sqrt{2g}\cdot H^{\frac{3}{2}}</math> | <math>Q=\frac{2}{3}C_{d}\cdot L\sqrt{2g}\cdot H^{\frac{3}{2}}</math> | ||

{{Plainlist|1=Where: | {{Plainlist|1=Where: | ||

− | *''C<sub>d</sub>''= discharge coefficient (default 0.62 for a 'sharp edge). | + | *''C<sub>d</sub>'' = discharge coefficient (default 0.62 for a 'sharp edge). |

*''L'' = Length of the weir (m) | *''L'' = Length of the weir (m) | ||

*''g'' = Acceleration due to gravity (9.81 m/s<sup>2</sup>) | *''g'' = Acceleration due to gravity (9.81 m/s<sup>2</sup>) | ||

*''H'' = Height of water over the weir (m)}} | *''H'' = Height of water over the weir (m)}} |

## Revision as of 17:12, 3 July 2019

The most common form of weir in LIDLow Impact Development. A stormwater management strategy that seeks to mitigate the impacts of increased urban runoff and stormwater pollution by managing it as close to its source as possible. It comprises a set of site design approaches and small scale stormwater management practices that promote the use of natural systems for infiltration and evapotranspiration, and rainwater harvesting. practices is a rectangular weir, in the form of a check dam or flow control in a swale or other open channel.

The flow (Q), may be calculated by measuring the height of water on the sill of the weir\[Q=\frac{2}{3}C_{d}\cdot L\sqrt{2g}\cdot H^{\frac{3}{2}}\]

Where:

*C*= discharge coefficient (default 0.62 for a 'sharp edge)._{d}*L*= Length of the weir (m)*g*= Acceleration due to gravity (9.81 m/s^{2})*H*= Height of water over the weir (m)