VNotch Weir Discharge Calculation  

Where,
q = Flow Rate
C_{d} = Discharge Constant
θ = V  Notch Angle
g = gravity (9.81 m/s²)
h = Head on the Weir
Example:
Calculate the Flow rate in Vnotch weir for the given details.
V  Notch angle (θ) = 25 degree
Head on the Weir (h) = 20
Discharge Constant (C_{d}) = 15
Solution:
Apply Formula:
q = 8/15 ×C_{d} × (2g)1/2 × tan(θ/2) ×h^{3/2}
q = 8/15*15*(2*9.81)*tan(25/2)*20 ^{3/2
}Flow Rate (q) = 702.6510823885201 m^{3}