Engineering History and 2008 Operation of the Bonnet Carré Spillway:A Controlled Levee Crevasse on the

Lower Mississippi River

Christopher G. Brantley, Ph.D.Christopher G. Brantley, Ph.D.

June 2008June 2008

Mississippi River Drainage BasinMississippi River Drainage Basin

Floods in the Lower Mississippi Valley Levee construction begins in 1718Levee construction begins in 1718 Increasing state and Federal involvementIncreasing state and Federal involvement Rising flood heights and larger leveesRising flood heights and larger levees Floods cause crevasses (breaks in the levees Floods cause crevasses (breaks in the levees

which flood adjoining areas)which flood adjoining areas) The Bonnet Carré Crevasses occur between 1849 The Bonnet Carré Crevasses occur between 1849

and 1882and 1882

The Great Flood of 1927

Floodwaters cover 27,000 square milesFloodwaters cover 27,000 square miles Approximately 250 - 500 people dieApproximately 250 - 500 people die 700,000 people are homeless700,000 people are homeless 137,000 buildings damaged or destroyed137,000 buildings damaged or destroyed $347 Million in damages ($4.4 Billion in 1993 dollars)$347 Million in damages ($4.4 Billion in 1993 dollars) 13 major levee crevasses occur13 major levee crevasses occur Levee at Caernarvon is purposely breached to save New Levee at Caernarvon is purposely breached to save New

OrleansOrleans

Corps abandons “Levees only” Policy

Corps recommends Jadwin Plan which drops Corps recommends Jadwin Plan which drops “levees only” policy“levees only” policy

1928 Flood Control Act gives Corps jurisdiction 1928 Flood Control Act gives Corps jurisdiction over flood control in Lower Miss. Valleyover flood control in Lower Miss. Valley

Bonnet Carré selected as site for controlled Bonnet Carré selected as site for controlled spillway to protect New Orleans spillway to protect New Orleans

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NEW ORLEANS

NEW ORLEANS

BATONROUGEBATONROUGE

NATCHEZNATCHEZ

VICKSBURGVICKSBURG

GREENVILLEGREENVILLE

ARKANSASCITY

ARKANSASCITY

MEMPHISMEMPHIS

CAIROCAIRO

HELENAHELENA

NEW MADRIDNEW MADRID

ST. LOUISST. LOUIS

1,25

0,00

01,

250,

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1,20

0,00

01,

200,

000

300,

000

300,

000

Wax LakeOutlet

Wax LakeOutlet

1,50

0,00

01,

500,

000250,000250,000

WestAtchafalayaFloodway

WestAtchafalayaFloodway

MorganzaFloodwayMorganzaFloodway

RED RIVER

RED RIVER

620,000620,000

600,000600,000

OldRiverOld

River

250,000250,000

1,50

0,00

01,

500,

000

YAZOO RIVERYAZOO RIVER2,

890,

000

2,89

0,00

0

540,000540,000400,000400,000

TENNESSEE RIVER

TENNESSEE RIVER

OHIO RIVER

OHIO RIVER

2,250,0002,250,000

550,000550,000

New MadridFloodway

New MadridFloodway

100,000100,000

MISSOURI RMISSOURI R

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150,

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150,

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490,000

490,000

Project DesignFlood

GULF OF MEXICOGULF OF MEXICO

LAKELAKEPONTCHARTRAINPONTCHARTRAIN

LAKELAKEPONTCHARTRAINPONTCHARTRAIN

Bonnet CarréSpillway

Bonnet CarréSpillway

LowerAtchafalayaFloodway

LowerAtchafalayaFloodway

BATONROUGEBATONROUGE

MORGANCITYMORGANCITY

NEWORLEANS

NEWORLEANS

Old River ControlOld River ControlOld River ControlOld River Control

Morganza FloodwayMorganza FloodwayMorganza FloodwayMorganza Floodway

Bonnet Carré SpillwayBonnet Carré SpillwayBonnet Carré SpillwayBonnet Carré Spillway

New Orleans DistrictNew Orleans DistrictNew Orleans DistrictNew Orleans District

GULF OF MEXICOGULF OF MEXICO

LAKELAKEPONTCHARTRAINPONTCHARTRAIN

LAKELAKEPONTCHARTRAINPONTCHARTRAIN

NEW ORLEANS

NEW ORLEANS

BATONROUGE BATONROUGE

MORGANCITY

MORGANCITY

OLDRIVEROLD

RIVERWESTATCHAFALAYA

FLOODWAY

WESTATCHAFALAYA

FLOODWAY

WAX LAKEOUTLET

WAX LAKEOUTLET

MORGANZAFLOODWAYMORGANZAFLOODWAY

BONNET CARRE’SPILLWAY

BONNET CARRE’SPILLWAY

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600,000600,000

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RED RIVER

RED RIVER150,000

150,000

350,000

350,000

Project Design FloodProject Design Flood Project Design FloodProject Design Flood

3 million cubic feet per second at Old River

The Bonnet Carré Spillway

Component of the Mississippi River & Tributaries Component of the Mississippi River & Tributaries Project authorized in 1928Project authorized in 1928

Built between 1929 and 1936Built between 1929 and 1936 Protects New Orleans by diverting flood waters to the Protects New Orleans by diverting flood waters to the

Gulf of Mexico via Lake PontchartrainGulf of Mexico via Lake Pontchartrain Operated first in 1937 and eight times thereafter (1945, Operated first in 1937 and eight times thereafter (1945,

1950, 1973, 1975, 1979, 1983, 1997, 2008)1950, 1973, 1975, 1979, 1983, 1997, 2008) Design capacity is 250,000 cubic feet per secondDesign capacity is 250,000 cubic feet per second

Design and Construction

Design ConcernsDesign Concerns Preliminary InvestigationsPreliminary Investigations Temporary Hydraulic Laboratory on-siteTemporary Hydraulic Laboratory on-site Concrete TestingConcrete Testing Simple and enduring designSimple and enduring design

7,000 foot concrete weir7,000 foot concrete weir 350 bays, each with 20 wooden timbers350 bays, each with 20 wooden timbers

174 low @ 15 feet NGVD174 low @ 15 feet NGVD 176 high @ 17 feet NGVD176 high @ 17 feet NGVD

Construction Photos

Untreated wooden pilings

Concrete Piers

Project Operations

Decision ProcessDecision Process Numerous factors are consideredNumerous factors are considered Predicted river stages and velocities are most Predicted river stages and velocities are most

important factorsimportant factors Operation ProceduresOperation Procedures

Two cranes lift needles over 36 hoursTwo cranes lift needles over 36 hours Design allows tight control over flowsDesign allows tight control over flows

Spillway Opening DataYearYear Dates OpenDates Open Gates Gates

OpenOpenPeak FlowPeak Flow

19371937 Jan 30 to Mar 7Jan 30 to Mar 7 285285 211,000211,000

19451945 Mar 23 to May 18Mar 23 to May 18 350350 318,000318,000

19501950 Feb 10 to Mar 19Feb 10 to Mar 19 350350 223,000223,000

19731973 Apr 8 to Jun 21Apr 8 to Jun 21 350350 195,000195,000

19751975 Apr 14 to Apr 26Apr 14 to Apr 26 225225 110,000110,000

19791979 Apr 18 to May 21Apr 18 to May 21 350350 191,000191,000

19831983 May 20 to Jun 23May 20 to Jun 23 350350 268,000268,000

19971997 Mar 17 to Apr 18Mar 17 to Apr 18 298298 243,000243,000

20082008 Apr 11 to May 8Apr 11 to May 8 160160 115,000115,000

Bonnet Carré Spillway

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ubic

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Discharge

USGS Discharge

Other Activities

HuntingHunting FishingFishing ATV ridingATV riding Dog trainingDog training CampingCamping CyclingCycling ArcheryArchery BoatingBoating CrawfishingCrawfishing Borrow (sand and clay)Borrow (sand and clay)