V-Notch (Triangular) Weir

Units

Notch angle, θdeg

Head, Hft

Coefficient, C_d—

Discharge, Q—cfs

$$ Q = \tfrac{8}{15} \, C_d \, \sqrt{2g} \, \tan\!\left(\tfrac{\theta}{2}\right) H^{5/2} $$

C_d is typically 0.58–0.61 for a fully-contracted thin-plate notch; 0.58 is the usual design value for a 90° weir. H is measured from the notch vertex.

via PE-Calc — V-Notch Weir