Today’s discussion

1. Infrastructure Resiliency Planning: Keeping Downtown Economies StrongBest Practices for Assessing Climate Risk from Extreme Rainfall EventsLaurens van der Tak

2. Today’s discussion • Why Consider Climate Risk for Downtown Facilities • Climate Risk – a Primer • Climate Scenarios and Uncertainty • Examples

3. 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

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

5. 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)

6. 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?

7. High Probability Low Low High Consequence Climate risk is just one among multiple risk factors to evaluate likelihood and consequence of facility failure Net Future Risk Future Climate Risk Existing Risk Other Future Risk Reduced Risk

8. 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

9. Select a range of GHG emission scenarios to envelope or bookend potential climate uncertainty, ID suitable GCMs/ensembles (IPCC) A1FI A2 A1B B2 A1T B1 Scenarios for GHG emissions from 2000 to 2100 in the absence of additional climate policies. (IPCC 2000)

10. Global-regional scale Local-national scale How do we defensibly and efficiently translate global climate science to local impacts and wet weather planning action • Global Information • Changing Climate science • General Circulation Models • Emission Scenarios • lmpact assessment • IPCC Assessment Reports Climate science and scientists operate at global scale Large gap • Local Concerns • Defensible risk assessment • Temp and precip change • Catastrophic events • Sea level change • Adaptation effectiveness • Cost and timing Impacts, planning, and action are local

11. Global-regional scale Global-regional scale Local-national scale Local-national scale A solution: a modeling environment to bridge the gap between global climate science and local impacts and action: SimCLIM • 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

12. 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 Storm sewer infrastructure planning with climate change risk: A Case Study—Alexandria Virginia Hurricane Isabel flooding, September 2003Photo Credit: Mark Young/The Journal Newspapers

13. 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% -

14. Alexandria Virginia: Change in Rainfall Frequency

15. Daily Rainfall Extremes – Intensity and Frequency A1FI (highest), 12 GCMs The intensity of a 10 yeareventwillbe15% higher by 2050

16. 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

17. 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

18. Permeable pavement options fit into downtown streetscapes

19. 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

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

21. Source: Climate Adaptation and Transportation, CCAP, May 2012

22. Infrastructure Resiliency Planning: Keeping Downtown Economies StrongBest Practices for Assessing Climate Risk from Extreme Rainfall EventsLaurens van der Tak