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 flooding Minneapolis / 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, 2009 Orchard 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 Heavy Precipitation 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 Low Consequence Low Probability Existing 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 ( ), 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 Growth A1FI - Fossil Intensive A1T - Non-fossil A1B – Balanced Second Highest Greenhouse Emissions A2 – Heterogeneous High Population Growth Slow Economic and Technology Change Highest Greenhouse Emissions B1 – Convergent World Same Population as A1, more service and information technology. Lowest Greenhouse Emissions B2 – Intermediate Population growth, local solutions. Second Lowest Greenhouse Emission A1FI B2 A2 B1 A1T 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 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 2003 Photo Credit: Mark Young/The Journal Newspapers

Projected Annual Precipitation (Reagan National Airport, DC) 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 Frequency A1FI (highest), 12 GCMs The intensity of a 10 year event will be 15% higher by 2050

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 16

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 17

Permeable pavement options fit into downtown streetscapes

Detention systems can be multifunctional in downtown urban areas 19 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

Floodproofing can protect high value assets from infrequent but potentially damaging floods 20 Retrofitted rising flood barriers along Orchard Road, Singapore.

21 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