scope:

This method covers the measurement of the rate of flow <;Jf water and waste water in open channels or streams at or near the ground surface using the triangular (V-notch), rectangular and trapezoidal type weirs having end and bottom contractions.

Weirs are particularly applicable where there is low head flow at liquid ·discharge outlets for relatively clear water containing a minimum of suspended solids which, on low flows, tend to settle out upstream.