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!

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