US Army Corps of Engineers

BUILDING STRONG®

Flood Frequency of a Regulated River 

– The Missouri River

Douglas J. Clemetson, P.E.

Chief, Hydrology Section

USACE, Omaha District

Omaha, Nebraska

30 January 2013
BUILDING STRONG®
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0

10

20

30

40

50

60

70

80

90

100

110

1900 1910 1920 1930 1940 1950 1960 1970 1980 1990 2000

Storage in MAF

Missouri River Basin Reservoir Storage
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0

50

100

150

200

250

300

350

400

1900 1910 1920 1930 1940 1950 1960 1970 1980 1990 2000 2010

Flow (1000 cfs)

Missouri River at Omaha

Annual Maximum Daily Flow
BUILDING STRONG®

0

5000

10000

15000

20000

25000

30000

1930 1940 1950 1960 1970 1980 1990 2000 2010

Flow (cfs)

Missouri River at Omaha

Annual Minimum Daily Flow
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DEFINITIONS

 Unregulated Flow = Historic Flow + Historic Holdouts

 Regulated Flow = Historic Flow - (Present Condition 

Holdouts - Historic Holdouts)

 or, Regulated Flow = Natural Flow - Present Condition 

Holdouts

 Holdouts = Res Storage Change + Irrigation + M&I + GW 

Depletion + Reservoir Evaporation + ...
BUILDING STRONG®

0

10

20

30

40

50

60

1890 1910 1930 1950 1970 1990

Year

Holdout

Historic

Current Level

Comparison of Holdouts

Present Condition
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0

10

20

30

40

50

60

70

Jan Mar May Jul Sep Nov

Flow

0

10

20

30

40

50

60

70

Jan Mar May Jul Sep Nov

Flow

Present Condition Holdouts

Historic Holdouts

Unregulated Flow

Regulated Flow

Definition Sketch of Unregulated and Regulated Flow
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METHODS

 Unregulated Flows (Historical Holdouts)

 Unregulated Flow Development Model (UFDM) 

 Regulated Flows (Present Condition Holdouts)

 Daily Routing Model (DFRM)
BUILDING STRONG®

Year

Annual Peak Discharge in cfs

Sioux City Sioux City Omaha Omaha Neb City Neb City

Regulated Unregulated Regulated Unregulated Regulated Unregulated

1898 62000 175000 63000 168400 79600 206400

1899 64100 254000 76600 241700 142000 273000

1900 49900 131400 66600 122000 69900 177600

1901 59200 150600 56100 144200 75800 182100

1902 49300 132700 50700 124800 68700 166800

1903 53700 152700 62000 152900 125200 223300

1904 57200 180400 84900 184700 74500 184000

1905 56400 239000 38000 175300 84800 244500

1906 51700 184300 75600 200800 82600 195700

1907 52700 184300 70200 194900 94000 231300

1908 64800 188000 89700 232000 107500 260200

1909 71200 174500 132800 217200 126100 236000

1910 49400 204600 115400 231900 98200 207000

1911 48100 141500 69100 158400 94400 175300

1912 62500 194500 84200 204100 181200 225900

1913 62300 200700 122900 208000 106000 205600

1914 64700 158900 57100 140900 101800 239000

1915 64100 181100 70900 178200 92700 210200

1916 65600 186900 71900 176600 86800 212300

1917 63500 201400 86900 206800 94900 223600

1918 57000 183300 73400 188500 85500 211400

1919 40400 141800 79200 151900 83400 150500

1920 40100 201100 115500 233500 133300 270300

1921 46200 180200 72100 215500 126100 296600

1922 38100 163500 62700 180500 80100 216200

1923 64400 157200 96000 190000 106300 230700

1924 61500 134800 77700 151400 125800 213200

1925 55200 173900 77600 205800 79200 218000

1926 37300 114700 72600 122300 78000 156700
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Gavins Point Dam June 16, 2011 – Release=150,000 cfs
BUILDING STRONG® 99 95 90 80 50 20 10 5 1 0.1

2 5 10 20 100 1000

10,000

100,000

1,000,000 Peak Flow (cfs)

Percent Chance Exceedance

Missouri River at Sioux City

Unregulated Bulletin 17B

Unregulated Adopted

Regulated Adopted

1898-1997 Regulated

1898-2011 Regulated

1898-1997 Unregulated

1898-2011 Unregulated

Return Period 

99 95 90 80 50 20 10 5 1 0.1

2 5 10 20 100 1000

10,000

100,000

1,000,000 Peak Flow (cfs)

Percent Chance Exceedance

Missouri River at Omaha

Unregulated Bulletin 17B

Unregulated Adopted

Regulated Adopted

1898-1997 Regulated

1898-2011 Regulated

1898-1997 Unregulated

1898-2011 Unregulated

Return Period 
BUILDING STRONG®

0

50000

100000

150000

200000

250000

0 100000 200000 300000 400000 500000

Regulated Flow cfs

Unregulated Flow cfs

Missouri River at Omaha Regulated-Unregulated Relationship

Paired 1898-2011

Paired 1898-1997

Sorted 1898-2011

Sorted 1898-1997

Design Floods

Adopted 2003
BUILDING STRONG®

Questions/Discussion