Adapting to Future Hurricane Risk Under Climate Change Uncertainty:

Developing and Implementing Robust Strategies for a More Resilient New Orleans.

David Groves, PhD, Rand Corporation; Jordan Fischbach, PhD, Rand Corporation; Henry Willis, PhD, Rand Corporation; Lauren Andrews, Rand Corporation; David Johnson, Rand

Corporation; Amy E Lesen, PhD*, Dillard University; Earthea Nance, PhD, University of New Orleans; Mark Davis, J.D., Tulane University; Courtney Hill, Dillard University.

5 April 2013

HBCU Student Climate Change Conference

Dillard University

Funding provided by the NOAA SARP program

Study Explored Three Components of Managing Long-term, Uncertain Risks

1. New Orleans flood risk assessment

2. Risk mitigation decision-support for New Orleans

3. Risk communication to support locally-managed risk mitigation programs

Study Explored Three Components of Managing Long-term, Uncertain Risks

1. New Orleans flood risk assessment

2. Risk mitigation decision-support for New Orleans

3. Risk communication to support locally-managed risk mitigation programs

NOLArisk Model Estimates Flood Risk toNew Orleans from 2011-2060

• BUILDS ON OTHER MODELS USED BY FEMA AND OTHER AGENCIES

• Included climate change data in the model, which is different from other models used to this point

Allows decision makers to:• Test location-specific strategies• Consider a wider range of uncertainty than recent Army Corps

estimates

Model Covers Many Scenarios and MeasuresUncertainties Policy Options

Coastal degradation by 2060Relative sea level rise (RSLR in mm/year)Protection system maintenanceResidential growth rate (homes/yr)Growth dispersion (in/out of OM basin)Program participation rateProgram lengthEnforcement parameter Induced development multiplier Elevation cost multiplierBuyout/easement cost multiplierAmphibious housing cost multiplier

Lift slab-on-gradeElevate existing pier-foundationSecond-story conversionDemolish and reconstruct on-siteAmphibious housingBuyoutsPermanent easementsDry flood proofingBarriers/bermsFacility relocation

Different modeling approaches Storm damage scenarios

Flood hazards moduleFlood consequences moduleMitigation strategies module

100, 400, and 1,000-yr. equiv. ann. damagesExpected annual damagesImplementation costsCost effectiveness (400-yr. risk vs. cost)Benefit-cost ratio

Legend

100-year damage in 2060 (low/low scen., 2009$)$0

$1-8 million

$8-16 million

$16-32 million

$32-64 million

$64-128 million

>$128 million

Lake Pontchartrain

Mississippi River

St.Bernard Parish

Jefferson Parish

0 1 2 3 40.5Miles±

LACPR “low/low scenario” assumptions:• Relative sea level rise = 2 mm per year (0.1 m by

2060)• No additional landscape degradation• Declining population (-0.32% per year)

Under Favorable Assumptions, Estimates for 100-yearFlood Damage in 2060 Remain the Same as in 2011

FrenchQuarter

Lower 9th

Ward

New Orleans East

Lakeview Gentilly

Viavant / Venetian Isles

Legend

100-year damage in 2060 (adverse scen., 2009$)$0

$1-8 million

$8-16 million

$16-32 million

$32-64 million

$64-128 million

>$128 million

Lake Pontchartrain

Mississippi River

St.Bernard Parish

Jefferson Parish

0 1 2 3 40.5Miles±

Adverse scenario assumptions:• Relative sea level rise = 10.7 mm per year (0.5 m by 2060)• Substantially degraded landscape (81% of LACPR worst-case)• Increasing population (0.62% per year)

Under Less Favorable Assumptions, Damage Increases

FrenchQuarter

Lower 9th

Ward

New Orleans East

Lakeview Gentilly

Viavant / Venetian Isles

Study Explored Three Components of Managing Long-term, Uncertain Risks

1. New Orleans flood risk assessment

2. Risk mitigation decision-support for New Orleans

3. Risk communication to support locally-managed risk mitigation programs

We Worked With the New Orleans branch of the Louisiana Governor’s Office of

Homeland Security and Emergency Management

• Provide support implementation of New Orleans Master Plan as part of FEMA mitigation grant program

• Develop web-based tool to enable city staff members to evaluate analysis results

– Assess potential effect of different mitigation strategies– Analyze wide range of plausible future conditions

… Against Scenarios Reflecting Uncertainties

Uncertainties• Coastal degradation by 2060• Relative sea level rise (RSLR in

mm/year)• Protection system maintenance• Residential growth rate

(homes/yr)• Growth dispersion (in/out of OM

basin)• Program participation rate• Program length• Enforcement parameter • Induced development multiplier • Elevation cost multiplier• Buyout/easement cost multiplier• Amphibious housing cost

multiplier

254 different combinations of scenarios

Scenarios

Exploration Over Neighborhood Reveal Areas of High Risk and Mitigation Potential

Consider aspecific neighborhood:Tall Timbers / Brechtel

100-yr Equivalent Annual Damage

400-yr Equivalent Annual Damage

Additional Elevation Reduces Residual Risk Under Nominal Assumptions…

400-year damages100-year damages

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…but Much Higher Damages Are Estimated Under Other Plausible Future Scenarios

400-year damages100-year damages

100-

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400-

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Study Explored Three Components of Managing Long-term, Uncertain Risks

1. New Orleans flood risk assessment

2. Risk mitigation decision-support for New Orleans

3. Risk communication to support locally-managed risk mitigation programs

Risk Communication Must Give People What They Need To Make Informed Decisions

• Present best available understanding of risk– Be honest and open about uncertainty– Reveal what can be done to reduce risks– Discuss what residual risks will remain

• Address all issues that people feel are relevant– For example, how might new elevation standards affect

neighborhood livability?

• Identify and correct common misconceptions

We used the Mental Models Approachto Risk Communication

1. Describe the “expert view” of the problem

2. Conduct open-ended interviews eliciting people’s beliefs about the problem

3. Contrast expert and public views and refine the “expert model”

4. Draft, evaluate and revise communication materials

Source: Morgan et al, 2002

We completed the first three steps of this process

We completed the first three steps of this process

Expert Model Describes Factors Affecting Decisions About Mitigating Flood Risk

We Interviewed 20 New Orleans Homeowners• Age

– 31-40yrs (3)– 41-50yrs (3)– 51-60yrs (11)– >61yrs (3)

• Race– African American (9)– Caucasian (11)

• Education– At least BA/BS degree (10)– Less than BA/BS degree (10)

• Gender– Female (9)– Male (11)

• Race– African American (9)– Caucasian (11)

• Flooded during Katrina (13)

Preliminary Analysis Suggests Several Hypotheses About Risk Communication

• Interview protocol revealed discussions of the entire expert model

– 80%-100% of expert model topic areas mentioned across interviews

• Several topics may be not relevant to decisions or poorly understood, for example

– National flood programs (10%)– Link to sea level rise (5%)– Link to coastline maintenance (15%)

Some Concepts Mentioned Were Outsideof the Expert Model

• Belief that Katrina flooding may have been caused by human action (there is historic precedence for this – 1927 flooding)

– Must address these interactions (environmental and climate justice work)

• Perception of inequity in protection across race or economic status– Must address these inequities (environmental and climate

justice work.

• Belief that public doesn’t have enough information about choices– Must address unmet demand for risk communication

• Ownership and use affects decision-making.– Is property inherited and owned outright?– Is property rented or lived in?– These incentives may have import for program design and

implementation

Summary• Modeling and analysis can help risk managers account

for long range, uncertain risks

• Mental models approach can identify topics to address through risk communications

• Models, analysis, and risk communication can be used in an integrated manner

• Opportunities exist to extend these findings– Apply method in other areas (e.g., Miami or

Charleston)

Future Work• Participatory and collaborative work with local

communities

• Look further into decision-making processes of local residents

• Continue work with Governor’s Office of Homeland Security on how to communicate risk to residents and increase participation in hazard mitigation programs