Flow depth at the spillway toe

[SMIAH]

This is probably an easy one but...
What is a suitable method for determining the flow depth at the toe of a dam spillway.
Should it be based on Manning formula or an energy method or else.

 

[gbam]

Depends on the spillway slope.

 

[cvg]

also depends on discharge and where you are measuring the depth. is it before or after the hydraulic jump?

 

[SMIAH]

Before the hydraulic jump (the corresponding depth after the hydraulic jump is easy to obtain).

I have this...:

V1 = (2g(Z+Ha-y)^0.5

Where
V1 = Theorical velocity at the toe of the spillway
Z = is the fall or vertical distance in ft from the upstream reservoir level to the floor at the toe
Ha = Upstream velocity head
y1 = Depth of flow at the toe

The actual velocity is always less than the theorical velocity due to energy loss involved.

 

[ropotto]

Equations for hydraulic jump in horizontal rectangular channel (Chaudhry, 1993; Chow, 1959):

V=Q/(yB) F=V/(gy)0.5 y2/y1 = 0.5 [(1+8F12 )0.5 - 1]

L = 220 y1 tanh[(F1-1)/22] h = (y2-y1)3 /(4y1y2)

where:
B=Channel width (m), F=Froude number (dimension-less), g=acceleration due to gravity (9.8066 m/s2), h=Head loss (m), L=Length of jump (m), Q=Discharge (m3/s), tanh=Hyperbolic tangent trigonometric function, V=Velocity (m/s), y=Water depth (m)