galloway bangkok adb flood management forum 2012

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Flood Risk Management:

Recent US Experiences and Lessons Learned

January 19-20, 2012

Bangkok

Gerald E. Galloway, Jr., PE, PhDWater Policy Collaborative, University of Maryland

[email protected]

International Knowledge Sharing Forum

on Flood Management


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The Bottom Line US Lessons Learned1. Absolute protection from floods is not possible - plan for

exceedence

2. Cannot not rely on single structural approach - implementa portfolio of measures

3. Risks must be identified and decisions made based onrelative risk everyone will not get same protection

4. Decisions must be made with imperfect knowledge - thefuture will be different from the past

5. Responsibilities must be clear - all groups must shareresponsibilities and take local actions

6. Life-cycle infrastructure needs and costs must beaddressed

7. Effective communication of risk is essential


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Floods Have Been Part of North American History


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And People Tried to Deal with the Flood Challenge


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The Mississippi Basin Drains 41% of the

Contiguous United States

Mississippi River Basin3.1 million km2

32% of total US farm acreage

Ohio

Missouri

Mississippi

Mississippi RiverLength - 3730 km

Average flow 12,700,000 m3/sMax Flow -85,000 m3/s


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Levees Became the Way of Life Levees Only


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And More Recent US HistoryA Major Flood Occurred in 1927

and Gained National Attention


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The 12 Month Solution:

Federal Levees, Floodways, Off River

Storage, Revetment, Dredging, Dikes

Dams


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Floodways

andBackwaterAreas


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Miss aerial (memphis)
http://blogs.sacbee.com/photos/2011/05/high-water-pushes-past-memphis.html


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Jeff Roberson/AP
http://blogs.sacbee.com/photos/2011/05/high-water-pushes-past-memphis.html


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LOWERMISSISS

IPPIRIVER

ATCH

AFALAYARIVER

NEWORLEANS

BATON

ROUGE

NATCHEZ

VICKSBURG

GREENVILLE

ARKANSAS

CITY

MEMPHIS

CAIRO

HELENA

NEW MADRID

ST. LOUIS

1,250,000

1,060,000

1,500,000250,000

West

AtchafalayaFloodway

MorganzaFloodway

620,000

600,000

Old

River

250,0001,500,000

2,890,000

540,000400,000

550,000

New Madrid

Floodway

100,000

UPPERMISSISSIPPI

RIVER1

50,000 Project Design

Flood

LAKE

PONTCHARTRAIN

Bonnet Carr

Spillway

LowerAtchafalayaFloodway

30 / 70 Split

Wax LakeOutlet

MORGANCITY


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Birds Point-New Madrid AreaApril 29, 2011


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I

P j D i


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LOWERMISSISS

IPPIRIVER

ATCH

AFALAYARIVER

NEWORLEANS

BATON

ROUGE

NATCHEZ

VICKSBURG

GREENVILLE

ARKANSAS

CITY

MEMPHIS

CAIRO

HELENA

NEW MADRID

ST. LOUIS

1,250,000

1,060,000

1,500,000250,000

West

AtchafalayaFloodway

MorganzaFloodway

620,000

600,000

Old

River

250,0001,500,000

2,890,000

540,000400,000

550,000

New Madrid

Floodway

100,000

UPPERMISSISSIPP

RIVER1

50,000 Project Design

Flood

LAKE

PONTCHARTRAIN

Bonnet Carr

Spillway

LowerAtchafalayaFloodway

30 / 70 Split

Wax LakeOutlet

MORGANCITY


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(68,000 km2)

(26,300 km2)

(40,500 km2)


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BUILDING STRONG

Lessons Learned

The System performed as designed but work is needed to

repair, rebuild, complete and reinvest in the infrastructure

The Nation avoided damages in the 2011 flood of morethan $50 billion

The $13.9B invested in the System has prevented over$350 Billion in damages a 34-1 return on investment

547,000 acres was used for floodways and backwater

storage. The issue of floodways and off-river storage ispolitically sensitive. Communications are critical


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10 Million acre

feet = 12,300

Million cubic

meters


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Precipitation March 2011


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= 73,800 MM3


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20,000 MM3


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Lessons Learned


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BUILDING STRONG

Lessons Learned The Dam System performed as designed. It serves (8) multiple

purposes and therefore cannot capably handle the most extremeof flood events

Passing a major flood is expensive. Funds are needed to repair,rebuild, and reinvest in the infrastructure

There is a lack of public understanding of how floods are handledand personal responsibilities in handling

Flood risk can be mitigated beyond creating more space in theexisting Dam System designating floodways, establishing flood

corridor easements - structural and non-structural

Must organize around a common vision and with true purpose andacceptance of shared responsibility


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http://www.nwd.usace.army.mil/docs/MRIndependentReviewPanel.pdf

Dam Operation Review

Operators must follow manuals Operators must try to meet

needs; early release may harm

future needs

Operators must always protectstructures

Do not see how significant

changes could be made without

longer term forecasting


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Lessons Learned - Mississippi vs Missouri

Governance:

On the Mississippi, one agency (MRC) has primaryresponsibility for management of the flood and was able toexercise authority

On the Missouri, the responsibilities are divided among

many agencies

System Since 1927, the Lower Mississippi River has been

addressed as a single funding unit with flexibility inoperation

The Missouri operates for fiscal purposes as a series ofunconnected parts.


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What is USA Doing to

Deal with Floods?


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Katrina -2005 $120B Damages


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Failed Levees


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Failed Levees


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A willingnessto live withfloods

Individual and small

communities adaptto the naturesrhythm.

A desire toutilise thefloodplain

Fertile land in

floodplain is drainedfor food production.

Permanentcommunities areestablished on thefloodplain.

A need tocontrol floods

Large scalestructural

approaches areimplementedthrough organisedgovernance.

A need toreduce flooddamages

A recognition that

engineering alonehas limitations.

Effort is devoted toincreasing theresilience ofcommunities shoulda flood occur.

A need tomanage risk

A recognition thatnot all problems are

equal.Risk management isseen as an effectiveand efficient meansto maximise thebenefit of limitedinvestment.

From Living with Floods to Flood Control toManaging Risk

From Sayers et al , 2012


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Risk = f ( (p) Hazard * (p) Consequences))

Identify risks and make decisions based on relative risk recognize not all will get the same protection

R d i Ri k Absolute protection from floods


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Reducing Risk

Building Codes

Risk Communication

Evacuation Plans

Insurance

Natural Storage

Non-Structural (Floodproofing, Elevation, etc)

Structural (Levees, Dams, Floodways)

ResidualRisk

LocalState, Local

Federal, State, Local

Federal, State, Local, Individual

IndividualFederal, State, Local



Zoning

Initial Risk

Identify risks and make decisions based on relative risk recognize not all will get the same protection

Modified from USACE

Risk

is not possible must plan forexceedence (Residual Risk)

Cannot rely on single structural

approach - implement aportfolio of measures


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Recognise that decisions must be made with imperfectknowledge and that the future will be different from the past

49Climate Change and Development


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Life-cycle Infrastructure Requires Support

160,000 KM of LeveesOverall Condition = D-Update Cost= $50B

84,000 Dams

Overall Condition = DUpdate Cost= $50B

Th B Li US L L d


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The Bottom Line US Lessons Learned1. Absolute protection from floods is not possible - plan for

exceedence

2. Cannot not rely on single structural approach - implementa portfolio of measures

3. Risks must be identified and decisions made based onrelative risk everyone will not get same protection

4. Decisions must be made with imperfect knowledge - thefuture will be different from the past

5. Responsibilities must be clear - all groups must shareresponsibilities and take local actions

6. Life-cycle infrastructure needs and costs must beaddressed

7. Effective communication of risk is essential


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The Memory of a

Flood Is VeryShort

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Thank You

galloway bangkok adb flood management forum 2012

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