Infrastructure Resiliency Planning:

Keeping Downtown Economies Strong

Best Practices for Assessing Climate Risk from Extreme Rainfall Events

Laurens van der Tak

1

Today’s discussion

Why Consider Climate Risk for Downtown Facilities Climate Risk – a Primer Climate Scenarios and Uncertainty Examples

Why consider climate change for infrastructure planning and design? Road drainage, stormwater and wastewater facilities typically are

designed for selected peak design storms, estimated based on historical records

Extreme events consistent with climate change could alter these design criteria resulting in significant over- or under-design of facilities, creating unnecessary capital expense, or non-compliance with permits, and significant economic damage to communities

Businesses close as Duluth faces historic floodingMinneapolis / St. Paul Business Journal

June 20, 2012

What are extreme rainfall events?

Consensus definition: events that are “rare”

When they occur, can have catastrophic effects on human activities, infrastructure, and the environment

Source: Paul Davies, UK Met Office, 2009Orchard Road, Singapore

Extreme rainfall events are becoming more frequent

Louisville, KY 2009: 5” in 90 minutes (1000-yr return interval is 3.83”/hour)

Washington, DC 2006: 11.3” in 6 days

Chicago, IL 2008: 6.7”in 1 day Atlanta, GA 2009: 13” in 1day Nashville, TN 2010: 13.6” in 2days Duluth, MN, 2012: 10” in 1 day

Increases in Amounts of Very HeavyPrecipitation 1958 to 2007 (USGCRP 2009)

What do these changes mean for facility planners:What future conditions will affect the function of our downtown infrastructure and

what questions should planners ask:

Will changing storm frequencies change design storm criteria for transportation and stormwater conveyance facilities? – Could a "10-yr" storm be expected to become a "2-yr storm“? – What liabilities could result from these changes?

Will rising sea level impact facility siting and sizing? - Is your outfall going to be partially or fully

submerged more often?- Will your facility need to be flood-proofed or

moved?

Climate risk is just one among multiple risk factors to evaluate likelihood and consequence of facility failure

High

HighLow

ConsequenceLow

ProbabilityExisting Risk

Reduced Risk

Future Climate Risk

Other Future Risk

Net Future Risk

How do we ID and address these risks: Create future plausible scenarios and consider uncertainty: which GCMs, GHGs, and planning horizons???Planning process should recognize that most underground infrastructure is

expected to have a service life of 100 years or more, so consider: Other plausible changes in the environment that could affect facility function

– population, land use, possible technology changes, possible changes in regulations, Projected climate change

– climate in long term (2100 or later), or, climate in near term (2030-2050), can the facility capacity can be expanded in phases

Creating portfolios of “no regrets” options that are customizable for range of possible future scenarios:– source control through green infrastructure, appropriate grey infrastructure, land use

planning, building codes that include flood proofing

Select a range of GHG emission scenarios to envelope or bookend potential climate uncertainty, ID suitable GCMs/ensembles (IPCC)

“Scenario Family” Description

A1 – Rapid GrowthA1FI - Fossil IntensiveA1T - Non-fossilA1B – Balanced

Second Highest Greenhouse Emissions

A2 – HeterogeneousHigh Population GrowthSlow Economic and Technology Change

Highest Greenhouse Emissions

B1 – Convergent WorldSame Population as A1, more service and information technology.

Lowest Greenhouse Emissions

B2 – Intermediate Population growth, local solutions.

Second Lowest Greenhouse Emission

A1FI

B2

A2

B1A1T

A1B

Scenarios for GHG emissions from 2000 to 2100 in the absence of additional climate policies. (IPCC 2000)

Global Information• Changing Climate science• General Circulation Models• Emission Scenarios• lmpact assessment• IPCC Assessment Reports

Local Concerns • Defensible risk assessment• Temp and precip change• Catastrophic events• Sea level change• Adaptation effectiveness• Cost and timing

Large gap

How do we defensibly and efficiently translate global climate science to local impacts and wet weather planning action

Global-regional

scale

Local-national

scale

Climate science and scientists operate at global scale

Impacts, planning, and action are local

Local-national

scale

SimCLIM—an integrated modeling system for assessing climate conditions that influence risk and resilience for built and natural infrastructure and operations Considers plausible, customized future scenarios for water, sea level and coastal issues, human health, ecosystems, agriculture, transportation, energy, and others Incorporates local data for consideration of local impacts

A solution: a modeling environment to bridge the gap between global climate science and local impacts and action: SimCLIM

Global-regional

scaleGlobal-regional

scale

Local-national

scale

Storm sewer infrastructure planning with climate change risk: A Case Study—Alexandria Virginia

Experiencing repeated and increasingly frequent flooding events

Review of stormwater design criteria and projected impacts of climate change

Using SimCLIM projections and post processing for 2050 and 2100 to assess sea level rise; and rainfall intensity, duration, and frequency

Evaluating infrastructure adaptation options to reduce impacts from sea level rise and flooding from more intense and frequent storms

Hurricane Isabel flooding, September 2003Photo Credit: Mark Young/The Journal Newspapers

Projected Annual Precipitation (Reagan National Airport, DC)Reagan National Airport Projected Annual Precipitation

Median from 5 GCMs, 3 SRES Emissions (B1, A1B, A1FI)

35.00

40.00

45.00

50.00

55.00

60.00

1990 2000 2010 2020 2030 2040 2050 2060 2070 2080 2090 2100Year

Ann

ual P

reci

pita

tion

(Inch

es)

Median 5 GCM B1 (Low) EmissionsMedian 5 GCM A1B (Medium) EmissionsMedian 5 GCM A1FI (High) Emissions

55.9” +44%

52.2” +35%

47.3” +22%

38.8”Total Precipitation projected to increase by 22 to 44% -

Alexandria Virginia: Change in Rainfall Frequency

Daily Rainfall Extremes – Intensity and FrequencyA1FI (highest), 12 GCMs

The intensity of a 10 year event will be 15% higher by 2050

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Best practices for assessing climate risk from extreme rainfall events for drainage infrastructure and downtown businesses

Consider range of plausible futures and risks Integrate climate risk with overall risk assessment Recognize service life of infrastructure Consider uncertainty by factoring in:

– An envelope of GHG emission scenarios (low, medium, or medium-high, high)– A range of GCM models (downscaled to project scale)

Use a science-based, updatable, efficient tool set to implement this approach for defensible outcomes and implementable solutions

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Options for building resilience

Planning Avoidance Green Infrastructure

– Green Streets & Alleys– Green Parks– Green Parking Lots– Vegetated Roofs– Enhanced Tree Planting– Green Schools & Public Facilities

Detention Systems Flood proofing Emergency preparedness

Permeable pavement options fit into downtown streetscapes

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Detention systems can be multifunctional in downtown urban areas

Storage Pond used to Attenuate Storm Run-off in a New Development in Netherlands.

Dual-use Detention Storage Area in an Urban Community in Malmo, Sweden

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Floodproofing can protect high value assets from infrequent but potentially damaging floods

Retrofitted rising flood barriers along Orchard Road, Singapore.

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Source: Climate Adaptation and Transportation, CCAP, May 2012

Infrastructure Resiliency Planning:

Keeping Downtown Economies Strong

Best Practices for Assessing Climate Risk from Extreme Rainfall Events

Laurens van der Tak

22