FLOOD03466

• County: Statewide
• Basin: Statewide
• Title: Stream Channel Erosion Protection at Roadway Crossings
• Date: 8/1/1987
• Prepared By: USGS
• Floodplain - Doc Type: Floodplain Report/Masterplan

10.0

...
<D
Ie> ~
~ 0 1.0
<: '"
'0

J
n

rr
<:5
I-
U
<
u.
'"
'"
w
Z
:I:
<!>
::l
o
II:

0.10

0.01
1

n IZ 0.020
From laboratory flume study data.
curve published In HEC - 15
(Normann. 1975) and NCHRP
Study 108 (Anderson. 1970)

Range In roughness
coelflclent, n, for gravel,
cobble, and boulder bed
channels
n a 0.151

.

NOTES

CURVE
~-rg a l,26~)-0.5
d .167 0
a 50
d* . 0.20
a
no-19 0.525
de .167.0.794 + 1.85109 (~)
n ..jg 50
d 0.167 . 0.105: n a 0.0185 da 0.187
a
~ fj., (da )0.187
d' . 0.225 0
a 50

LIMITS
1.5<~ <35
050
da
35 < ~O < 30.000
50
da
1.5 <0: < 185
50

185 < d a < 30,000
050

1.5 < da <185
050

n . 0.041

.

.
.

-

.. Data From FHWA Study,
Culbe"aon (1984), Barnes (1967),
L1merlnos (1970), and Jarrett (1984)

CURVES A AND II ARE ENVELOPING LINES

A

.

n. 0.013
Range In roughness
coeHlclent. n. for
sand bed channels

II

c

D

E

A.6i&;& ~ui"'...& 1c:"

gravel bed channels

.

.-

.
.

..
-.

.
.

.

d
Lower limit ot ratios 0:: for sand bed channels (050<0.00328 feet)

100,000

FIGURE 7. Comparison of Manning~ roughness coefficient, n, derived from laboratory and natural channel data.

.

.

- '.
.- .... .
.... . .

o

. . .
. .
. .

.....- .
-".- . .
r ___
....- ......

Average curve for
sand bed channels

Upper 111M of ratios g:o
for gravel bed channels
(050>0.00328 teet)

10

100

1,000

dB
050 '

~

10.000

RELATIVE ROUGHNESS.