FLOOD09931

• County: Statewide
• Community: Urbanizing Areas of Colorado
• Basin: Statewide
• Title: A Guide for Erosion & Sediment Control in Urbanizing Areas of Colorado
• Date: 1/1/1973
• Prepared For: State of Colorado
• Prepared By: USDA Soil Conservation Service
• Floodplain - Doc Type: Educational/Technical/Reference Information

IBased on Handbook of Channel DesiQn, SCS-TP-61)

. 3:1 Slde SlaDe.
~D~ Retardance

TrianQular .. bot.toa wldt.b .. bot.t.o. width lO' bo t to. width 12' bottolll widt.b.
Grade 0.2 0.3 0.0 0.. 0.2 0.3 0.0 ,. . 0.2 0.3 0.0 0.' 0.2 0.3 '.0 0.. 0.2 0.3 0.0 0.'
Q-cfs . : A . . . lA- . . . . . :4 . ' . . . . . . . . . . . . . . A . A . A . 1 A . ;4 . :4 . A
10 1.9:11 1.8:10 1.7: . 1.6: . 1.3: 12 1.1:tO 1.0: . :l.9: . 1.2:13 1.1:11 1.0110 0.9: . 1.1!14 1.0!1.2 0.9!11 0.81~ 1.0114 0.9;12 0.8111 C.7! 10
20 2.2j15 2.1113 1.. 11 1.ail0 1.S; 16 1.4 j14, 1.2112 1.1;10 1.4jl'1' 1.3:16 1.2114 1.1;12 1.3: 18 1.2:16 1.::>:13 ::>.9:11 1.2:19 1.1:1'1' 1.0h5 0.9h3
30 2.5:19 2.3116 2.2 10 2.0;1.2 1.8121 1.6 ;17 1.5116 1.3113 1.7122 1.:d19 1".4j 1'1 1.2114 1.5;22 1...12::> 1.2ltO 1.1!15 1. 3 ~21 1.2:19 1.2:t9 1.1! 17
., 2.. '" 2.5: 19 2.3 1. 2.2:15 2.:): 24 1.8 :21 1.7:19 1..5:16 1.8:24 1.'1'122 1.5:19 1.4:1'1' 1.7;26 1.5122 1.4120 1.2116 1.6j2'1 1.5;25 1.3j21 1.2119
"" 3.0 27 2.' .. 2.7 22 2.5:19 2.3;:1) 2.11ze 1.9122 1.7:19 2.1;30 1.9j26 1.9;24 1.6:21 2.:l :32 1.9128 1.'1':26 1.5:22 1.9:31 1.6:27 1.5125 1.3:21
., 3.1 .. 2.. .. 2.7 22 2._'" 2.313:) 2.1126 1.9122 2.4137 2.2132 2.::d28 1.8:24 2.3;39 2.1 ,. 1.9!3:l 1.7!26 2.1138 1.9 j3.. 1.8:31 1.6127
100 3.1 .. 2.. .. ... 40 ?" :""4 2.3:00 2.1:26 2.61.., 2.4b'1' 2.2:32 2.:) 128 2.4;41 2.2 37 2.113.. 1.9;3:> 2.3:44 2.1;38 1.9134 1.7;29
120 3.0 27 3.0 OS 2.. 00 2.,,!.:a 2.3 30 2.. o. 2.51-m 2.3134 2.1:30 2.6i46 2.0 41 2.2";37 2.0:32 2.5:50 2.3 :44 2.1:38 1.9:34
140 2.. '3 2.. 311 2.' 32 2.. ,. 2.7 " 2.5:39 2.3134 2.7 o. 2.' .. 2.3;39 2.1134 2.. 52 2.4146 2.2141 2.0.1313
100 3.' ,. 2.. '" 2.. 311 3.1 51 2.. ,. 2.7 .. 2.51~ 2.. .. 2.7 ,. I ^.51.... 2.3:39 2.7 .. 2;5:5:) 2.3144 2.1138
100 2.. 41 3.0 07 2.. 51 2.. ,. 2.4141 2.. 07 2.. 52 2.4:46 2.21,41
200 I ?5!44 2.. .C 2.7 ., 2.5150 .2.3144
2'" 3.0 .3 2.. 07 2.7 ., 2.5:5:)

liaTE: Par dlverslons bullt on slopes uDder 24 Ue avallab1e cro.....
sect.lonal area above nor.al Qro~d wlll allow a reduct.lon In
duUn depth aa followlI:

6" dept.b
of flow
\.",

I Freeboard
-*7----

m
"
:r
g:
-

'-^
""

""

.

por land slop.s of 1" or less rltduce deptb of fiow (taken frolll
DesiQn Table I 204.
Par land slopes of 1... to 2" redu~e dept.h of flow I t.aken froa
Desl QIl Table I 104.
Par land slopes Qreat.er than 2,. use depth of now taken froll
Deslgn Table.

Moraal
ground

.

l.-b---l

'or ElEaaple: A. diversion 6 feet. wlde wit.h a 2.15 toot. dept.h of now
is required t.o reaove un c',f.!!.. on a 0.4" grade. If tbls is
bu11t. em a 110 slope t.he depth ..,. be reduced ~'" t.hus obt.alnlnli
a now dep.b of 2.0 feet. The requlred cross_sectlonal area of
t.be channel plus t.hat. above noraal ground llne wlll be 34 square
f.et. correspondinQ t.o t.he 2.5 foot. depth. The (JII"erall heiil~t. of
dlversion wlll be 2.0 feet. plus 0.5 foot. freeboard or 2.15 feet.,
IDl~,t.ead of t.he orlQlnal 3.::> feet..

IS _ dept.h of now, feet.
b _ bot.toa wldt.b of channel, feet
A _ cbanne1 capacit.:r. sq. ft.., Including area below 0.5' freeboard
and excluding aI17 area less t.han :).5' depth of now
z _ side slope of channel (horlzontal to vert.lcal)

Il/lURTANT: To.ll desi,.ed dopths 'I II"", odd l,ubOGrd required by
State Standards and specifications to obtain ov,nJll heipt of temJCe
abow bottom of channel. For finaL check Oft cross-uctioncll area
subtruct required frnboard /rM settled height of diversion and
PrtltIich for cross-sectional area shOkll in table.

Diversion design table - "D" Retardance (V and Trapezoidal Section)
(Sheet 1 of 2)

3/2?'/53

4-L-861B-1