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CHANNEL CONVEYANCE By James Pennaz
Chief, Hydrologic Engineering Branch
Kansas City District
25 April 2012
1
MISSOURI RIVER
CREATION OF SELF SCOURING CHANNEL
• Bank Stabilization and Navigation Project
• Typical changes from Nov 1934 to Nov 2003
2
9 Nov 1934
3
19 Jun 1935 4
5 Oct 1935 5
19 Aug 1936 6
23 May 1946 7
March1977 8
4 Nov 2003 9
KANSAS CITY REACH
10
The Kansas City Reach
11
1920 Dikes and Revetments
12
1952 Dikes and Revetments
13
BUILDING STRONG 14
1994 Dikes and Revetments
15
BUILDING STRONG 16
1951, 1952, and 1993 Floods
17
SAINT JOSEPH REACH
18
~7-ft
~15-ft
19 19
20
FLOW MODIFICATION
Large peak flows no longer occur
21
Hydrograph at Sioux City
22
River Bend Cutoffs
• Steeper Channel
– Velocity Increases
– Channel adjustments
23
24
25
26
LEVEE STORAGE AND CONVEYANCE
DURING FLOODS
27
WATER LEAVING LEVEE SYSTEM 2011 FLOOD
28
Flood of 2007:
“Scientists, government officials and environmentalists agree that a two- decade-long project to restore Missouri River habitat helped reduce flooding last month. They just don't know how much.”
– Associated Press, June 8, 2007
29
Flood of 2011:
“Public lands along the Missouri River don't soak up nearly as much floodwater as previously believed.” … “They do have some effect on downstream flooding, but in a flood as large and as long-lasting as the one this summer, that effect will be insignificant.”
– The Missourian, July 5, 2011
30
Flood of 2011:
“Farmers John Sam Williamson of McBaine and Wayne Hilgedick of Hartsburg say they've noticed a difference. A high river level on the Boonville gauge doesn't seem to affect the river towns like it did before areas such as Overton Bottoms were set up. Brett Dufur, a bed and breakfast owner in Rocheport, also credited conservation areas for lessened flooding effects.”
– The Missourian, July 5, 2011
31
Overton South
Old Island Levee
Set Back Levee
May 11, 2007
Looking upstream 300-ft excavated breach (allows backwater)
Tadpole Chute
Take away: MRRP built a chute, some SWH, abandoned 2 island levees, large scale levee setback. 32
Overton South
0 2000 4000 6000 8000 10000 12000 14000530
540
550
560
570
580
590
600
610
Missouri River Corridor RM 146 to 199 Plan: UMRFFS 1% 3/26/2008 discludes old island levee (abandoned after 1993)
Station (ft)
Ele
vation
(ft)
Legend
EG May07
WS May07
Ground
Levee
Ineff
Bank Sta
.035 .023 .0468
RM 179.9
Old Island Levee abandoned after 1993. Area now floods and conveys water including Tadpole Island Chute.
DRAFT – PENDING PEER REVIEW
33
Overton South
Old Levee
Set Back Levee
May 11, 2007
Looking downstream
Tie-Back Levee (not breached)
34
Levee set back storage area
Take away: Levee set-back functions more as a storage area than significant flow conveyance. 35
Overton North
May 11, 2007
Looking upstream
Overton Chute
Old levee breached / abandoned
Take away: Levee abandoned upstream of I-70, a chute and some SWH / widening completed. 36
BLUF
• MRRP is looking into how Flood Control and Habitat can co-exist
• River widening and levee setbacks can reduce river stages during small floods
• Ability to reduce upstream stages through increased conveyance shows more promise than downstream flow attenuation
• Results vary depending on flow magnitude, type of action (widening/setbacks), etc.
37
Test of Concept
Do levee setbacks and channel widening change river stages?
38
Test of Concept Steady-flow Models
• Scenario A: Pre-recovery model (~1992 conditions)
• Scenario B: River widening - 150 feet
• Scenario C: B + 1,000-feet levee set back
• Scenario D: Levee set back – 1,000 feet
• Scenario E: No levees
39
0 2000 4000 6000 8000 10000 12000540
550
560
570
580
590
600
610
620
Missouri River Corridor RM 146 to 199 Plan: SCENARIO B 5/14/2008 150
Station (ft)
Ele
vatio
n (ft
)
Legend
WS UMRFFS 10-yr
WS UMRFFS 2-y r
WS 75% Exceedance
WS 10% Exceedance
Ground
Lev ee
Inef f
Bank Sta
.1 .023 .0476
0 2000 4000 6000 8000 10000 12000540
560
580
600
620
Missouri River Corridor RM 146 to 199 Plan: SCENARIO A 5/14/2008
Station (ft)
Ele
vatio
n (ft
)
Legend
WS 10-y r (354000cfs
WS 2-yr (204000cf s)
WS 25% (85500cfs)
WS 90% (32300cfs)
Ground
Lev ee
Inef f
Bank Sta
.1 .023 .0476
River Mile 184
River Widening
River Widening Geometry
40
1992 compared to 150-ft of Widening
-2.5
-2
-1.5
-1
-0.5
0
0.5
1
120 140 160 180 200 220 240
River Mile
Dif
fere
nc
e(f
ee
t)
354,000 cfs
85,500 cfs
42,900 cfs
32,300 cfs
River widened in model
DRAFT
10-yr
41
227.00
226.16
224.81
223.27
220.78
219.31
217.69
214.72
212.86
211.55
209.06
207.45
205.30
203.68
200.99 197.43 195.13
192.39
190.42 189.16
186.97
185.024
183.41
182.20
180.68
179.15
177.28
176.72
175.08
173.71
171.77
170.44
169.13
167.81
165.91
163.99
162.04
160.86
159.47
155.37
153.45
151.74
149.92
147.90
146.80
144.60
143.14 141.73
139.20 136.10 133.12
130.37
127.98 126.04
124.47 122.09
119.93 117.70 114.96 112.09
Legend
WS May07
Ground
Levee
Ineff
Bank Sta
Study reach SCENARIO A 1992 conditions
10-yr flood inundation
42
227.00
226.16
224.81
223.27
220.78
219.31
217.69
214.72
212.86
211.55
209.06
207.45
205.30
203.68
200.99 197.43 195.13
192.39
190.42 189.16
186.97
185.024
183.41
182.20
180.68
179.15
177.28
176.72
175.08
173.71
171.77
170.44
169.13
167.81
165.91
163.99
162.04
160.86
159.47
155.37
153.45
151.74
149.92
147.90
146.80
144.60
143.14 141.73
139.20 136.10 133.12
130.37
127.98 126.04
124.47 122.09
119.93 117.70 114.96 112.09
Legend
WS May07
Ground
Levee
Ineff
Bank Sta
Study reach SCENARIOS C&D 1,000-ft levee setback
10-yr flood inundation
43
-4
-3.5
-3
-2.5
-2
-1.5
-1
-0.5
0
0.5
1
130 140 150 160 170 180 190 200 210 220
Wat
er
Surf
ace
Dif
fere
nce
(fe
et)
Missouri River Mile
Widen Widen and setback Setback Levee Removal DRAFT
10-yr flood Scenarios vs. 1992 Model DRAFT – PENDING PEER REVIEW
River geometry modified in model
44
Additional Research Needed!
• Impacts of Revetments and Dikes
• Increased Roughness from Vegetation
• Upstream Reservoirs Impacts – Flow modification
– Sediment trapping
• River Bend Cutoffs (Steeper Channel)
• Constrictions (Levees, Bridges, Embankments)
• River Widening
• Impacts from Major Floods
45
Discussion
• Next Steps
– Do we want to do anything with this information?
– Ideas?
– Suggestions?
46 46
Thanks for your participation in today’s meeting!
47
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