FLOOD00925

• County: Statewide
• Community: State of Colorado
• Title: Colorado Flood Hydrology Manual - Section 22 Program
• Date: 9/1/1993
• Prepared For: CWCB
• Prepared By: US Army Corps of Engineers
• Floodplain - Doc Type: Educational/Technical/Reference Information

equation:

Equation (13) is solved by trial and error until:

h = he - dc
v

For an ogee spillway, the discharge coefficient, C q' is computed as:

C Q = C c * ( ~ )E
hd

where:

C c = coefficient based on ratio of he to he, Table 1
d. = depth of approach channel in feet
E = exponent based on ratio of he to hd, Table 1

With no tailwater submergence, the spillway discharge is then:

Q=C *L *h
Q E e1.5

Tailwater elevation may be computed from specific energy as:

het = 0.9 * (h . + E ./E . )

where:

het = specific energy at toe of spillway
he = specific energy at crest of spillway
E. = elevation of spillway crest
E. = elevation of spillway apron

(14)

(15)

(16)

(17)

Tailwater depth is then computed by trail and error from the following

(het - D) * D 2 = 1 * (Q/L.)
2g

where:

D = tailwater depth
Q = discharge
L . = width of spillway apron

A submergence coefficient is interpolated from Table 2 using:

hd + D
he

= he + E - E
. .
he

and

7-S0

(18)

(19)