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

8

TE,CHNIQUES OF WATER-RESOURCES INVESTIGATIONS

invert is determined similarly. Always obtain
the elevation of the crown at both ends of
the culvert. Also determine the elevations of
t.he ends of the culvert aprons,
Locate the positions of the culvert, wing--
walls, aprons, and other features, Measure the
length of the culvert and length of aprons
with a tape.

Skewed culverts

A skewed culvert is one in which the head-
wall is not normal to the centerline of the
culvert or, in the event of no headwall, the
end is not cut off squarely. Pipes and pipe-
arches as well as box culverts are sometimes
skewed. Where this occurs, measure the wing-
wall angle as for a normal culvert, as the acute
angle at which the wingwall and headwall join,
Measure the invert elevation for a skewed
culvert on a line normal to the axis of the
culvert and at the point where the full section
of the culvert begins (minimum section),
Measure the approach length, Lw, to the
invert line described above, Measure the
length of the culvert, L, between in vert lines,
the shortest length of the culvert.

5
....
"'
"' 4
LL
~
Z 3
0
;:: 2
0(
>
"'
...J
"'

(hl- z)_
Lwfor--- ->10
D '

(h1- z)
--Lw for ..---- ..;: 1 0 ~--
D '

Mitered culverts

Many pipes and pipe-arches are mitered to
be flush with the highway embankmen t.
Det.ermine t.he invert. elevnt.ion~ fit the extreme
ends of the pipe. Oft.en, t.he first. section of II
mitered pipe is laid 011 a different. slope frorn
the rest of the culvert; therefore, obtain also
the elevation of the invert at full pipe. Deter-
mine the elevation of the crown at both ends
of the full pipe section, :\feasure the total
length of the culvert to determine the slope
(z is measured at ends of the invert), Also
determine the short, leng-th (the full section
of the culvert) and the length of miter.
For headwater-diameter ratios less than 1.0
measure the approach length from section 1 to
the point where the headwater elevation inter-
sects the miter, figure 4. For ratios greater than
1.0, L. is the distance from section 1 to the
beginning of the full section of the culvert. For
outlet control, measure the length, L, to the
point where d, or h, intersects the downstream
miter, or for a culvert flowing full, to the end
of the full section,

,.------->1

12345678910
DISTANCE ALONG CHANNEL, IN FEET

Section 1 at station 0
FLOW TYPES 2,3,4,5, AND 6

: [ - L for types 4, 5. and 6 flow ----------4

ws

------------

ws
---..
--.1'

d2 measured at upstream invert

L for types 2 and 3 flow

d3 measured at downstream invert

Figure 4.-Approach and culvert lengths for mitered pipe.

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