FLOOD01621

• County: Statewide
• Community: State of Colorado
• Title: Flood Hazard Delineation on Alluvial Fans and Urban Floodplains
• Date: 1/1/2001
• Prepared For: State of Colorado
• Prepared By: J.S. O'Brien
• Floodplain - Doc Type: Educational/Technical/Reference Information

VI. FLO-2D Model Verification

Verification of the FLO-2D model has been established through
a comparison of the results with fi.eld data for a mudflow event in
utah. A comparison was also made wit:h the Army Corps of Engineers I
HEC-2 hydraulic model results for channel flow and flow across a
broad floodplain (USCOE, 1982). Th,e purpose of this comparison was
to demonstrate FLO-2D's capability to replicate predicted flow
hydraulics from a well-established model using an identical data
base.

6.1 River Channel Hydraulics

The channel routing component of the mudflow model was tested
for water using a hypothetical channel 22,500 feet long, with 15
variable geometry cross sections and four different slope reaches;
two steep and two mild reaches (F'igr. 5). Actual river cross
sections from a natural river reach were used, but the roughness
and slope were assigned fictitious values to insure both
supercritical and subcritical flow:;.

FIGURE 5

CHANNEL PROFILE FOR FLO--2D VS HEC-2 ANALYSIS

,-

210

. .
............ .

220

200

. . .
...........".............. .
. . ,

190

180

REAj.:H 2
S ::: 0.001

150

REACH 3
S: = 0.02
. . u, = 0:025-
L~ngth = 2.~lOO'

.-
,,.0
co
>
Il!
-
~"'

140

130 . . . . . . . . . . . , ]
REACH 4' 12
s - 0.003
120 . Ii ',. . 0.035 . . . . . . '. . . ... . ... . , .
!
Length 5.000' 0 Indicf1te~ C~lange in Channel ,
;
110 .... .. -,. " ,].3:.. . . . . . Cro':3s...:..Sectlob'al 'Geon1~tr.y . 1
15 4
100
0 25 50 75 100 125 150 175 200 29-
~;)

Channel Dist.ance in Feet. x 100

24