FLOOD06195

• County: Statewide
• Community: State of Colorado
• Basin: Statewide
• Title: Measurment of Peak Discharge at Culverts by Indirect Methods
• Date: 6/1/1968
• Prepared By: G.L. Bodhaine
• Floodplain - Doc Type: Educational/Technical/Reference Information

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MEASUREMENT OF PEAK DISCHARGE AT CULVERTS BY INDIRECT ME,THODS 43

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Use 0.88 for ratios <0.4

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~ 0.90
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....
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LlJ 0.80 -----~--.-
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Mitered pipe

0.70
0,4

0,6 0,8 1.0
RATIO OF HEADWATER HEIGHT TO PIPE

1.6

1.2 1.4
DIAMETER (Lh,7,- Z)j

Figure 25.-Variation of discharge coefficient with headwater-diameter ratio, tvpes 1, 2, and 3 flow in mitered
pipe set flush with sloping embankment.

Wingwall entrance

Pipe culverts set flush with vertical headwall
The addition of wingwalls to the entrance of
pipes 8et flush with a vertical headwall does
not affect the discharge coefficient, which can
he determined from table 5.

Box culverts
For box culverts with wingwalls and a square
top entrance the discharge coefficient is 0.87
for wingwall angles, 0, of 30-75~ and is 0.75
for the special condition when 0 equals 900,
If the top entrance is rounded or beveled, and
0' is between 300 and 750, select a coefficient
from table 5 on the basis of the value of wiD
or riD for the top entrance, but use 0.87 as the
lower limiting value. For the special cas'; when
o equals 900, if the top entrance is rounded, or
beveled, multiply the base coefficient (0.75)
by k, or kw from figure 21 or 22. For 'angl~
bet\veen 750 and 900, interpolate between'
0.87 and 0,75 to obtain the base coefficient and
apply the adjustment for rounding or beveling
as described above.

rProjeding entrance
(orrugctltd-metall pipes and pipe-arches
Determine the discharge coefficient for cor-
rugated-metal pipes and pipe-arches that extend
. .
past a headwall or embankment by first select-

ing the coefficient from table 5 that corresponds
to the particular vala-€ ~andthen mufti:
plying this coefficient by~justment factor
kL.

Concrete pipes with beveled end
The discharge coefficient for concrete pipes
with a beveled end that have a projecting
entrance is the same as for those with a flush
entrance and can be determined from table 5,

Mitered pipe set flush with slopi"g embankment

The discharge coefficient for pipes mitered
and set flush with a sloping embankment is
0.74. For corrugated-metal pipes and pipec
arches that project beyond the embankment,
multiply 0.74 by the adjustment factor kL,

Type 5 flow
Flush setting in vertical headwall
Box or pipe culverts
Determine the discharge coefficient for box
or pipe culverts set flush in a vertical headwall
from w.bleji. This includes square-ended pipe
or box, corrugated pipe, corrugated pipe-arch,
, , concrete pipe with a beveled end, and box
culverts with rounded or beveled sides.
Type 5 flow usually cannot be obtained when
flared pipe end sections are installed, Only for
LID ratios less than 6 and culvert slopes greater