FLOOD01385

• County: Statewide
• Title: Guide for Selecting Roughness Coefficient n Values for Stream Channels
• Date: 12/1/1963
• Prepared By: USDA Soil Conservation Service
• Floodplain - Doc Type: Educational/Technical/Reference Information

. .

Back Swamp Dredged Channel near Lumberton, North Carolina. Approximate
bottom width 15 feet. Picture taken in 1915.

I Date of obser.
I \'StlOD

M.1
'I",J!.'l,.

A\'er. .
.,.
maxI-
mum
depth

Coeffi.
cientol
rough-
n."
n

rn

~

Description of channel

Apr. 22,1916 "' 22.' "" 25.3 1.13 1.22 0. 000792 '.038 Qmr8t. straight; 250 feet long. OrOS8 sedi01l, abrupt variations in shape; for
Feb. 10,1915 2. 23.1 4{).' 32' 1.2' 1.4fi . 000880 .042 variation in size, see fig. 11, B. Side ,lopu fairly regular. Bottom, fairly
May 17,1916 U 23.3 "'". 35.6 1.65 1.67 . 000880 .034 regular. some holes. &Jilt sandy clay. COndition, mat of overhanging
Feb, 3,1916 ,., 24.6 129.6 66.' 1.96 251 .000024 .034 rBgged roots on both side slopes; no weeds or grass in channel; some roots
Jan. 20,1916 6.1 ".2 171.9 83.1 207 2.98 . 000600 .036 in bottom. Conltructed, winter 1913. (PI. 13, C Bnd fig. 10, n.)
May 13,1916 ., 25.' ""' 98.. 23' 3.34 . 000700 .038
Jan. 25,1915 ." 26.. 235.1 ".3 237 3.34 .00064<> .036
____n_..'...n '.. .u..._' unnn_. un_n" _n____ ..un._ .n.__'_" .n.___.

Mean
hy-
draulic
radius

Aver-
.,.
""'"
section

Aver.
sur:.f:ce
widtb

Slopeo!
water
surface

Moan
veloc.
Ity

Dis.
charge

-----

I Average mEUlmum depth at bankful stage.

Chawappah Creek Dredged Channel near Shannon, Mississippi. Approximate
bottom width 15 feet, Picture taken 1913,

I Date of obset.
I ,"Btion

Feb. 6,1913
Apr. 5,1913
Feb. 28, un3

Aver.
...
mell-
mum
depth

I Coeffi.
Slope of cient of
water rougb-
surface ness
n

Aver.
...
"""
section

Moan
veloc-
ity

Mean
hy.
draulic
radius

Aver-
su':oo
width

D1s-
cblU'ie

28
7.3
11.1
112.0

1&7
31.2
36.4

7.5.0
"""
1,162.6

41.0
156.0
282'

1.83
Ul
.....

1.95 0.000850
4. 20 . 000400
6. 05 . 000935

nnnn nnnnn _nn.._ .._un _h_n__ n.n_nn n.n_u

I Average maximum depth at banktul stage.

11

DMcrlption of channel

~036
.03'
.038

Cour,e, straight; 320 feet long. 0/'0&1 lection, very little varietlon in shape;
for variation in size, see fig. 2, D. Side llopu, quite regular except near
top and along edge of bottom. Bottom, quite remiar. Soil varies trom B
sandy loam at top to a waxy clay at bottom. Conditiont very little vega-.
taUon in channel; Irregularity of upper part of channel due to erosion.
Comtruc:Ud, May, 1911. (PI. 2, B and fig. I, D.)