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					 Infrastructure Resiliency Planning:
Keeping Downtown Economies Strong

  Best Practices for Assessing Climate Risk
        from Extreme Rainfall Events

              Laurens van der Tak

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
§ 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

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

   Orchard Road,
   Singapore                                     Source: Paul Davies, UK Met Office, 2009
Extreme rainfall events are becoming more frequent
§   Louisville, KY 2009: 5” in 90
    minutes (1000-yr return interval is   Increases in Amounts of Very Heavy
                                          Precipitation 1958 to 2007 (USGCRP 2009)
§   Washington, DC 2006: 11.3” in 6
§   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
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
Climate risk is just one among multiple risk factors to evaluate
likelihood and consequence of facility failure

                                      Future Climate Risk         Net Future Risk

                                                  Existing Risk           Other
                    Reduced Risk

              Low                                                             High
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 Growth          Second Highest
A1FI - Fossil Intensive    Greenhouse Emissions
A1T - Non-fossil
A1B – Balanced

A2 – Heterogeneous         Highest Greenhouse
High Population Growth     Emissions                                   A1FI
Slow Economic and
Technology Change

B1 – Convergent World      Lowest Greenhouse
Same Population as A1,     Emissions
more service and                                                            B2

information technology.                                                             A1T

B2 – Intermediate          Second Lowest
Population growth, local   Greenhouse Emission
solutions.                   Scenarios for GHG emissions from 2000 to 2100 in the
                              absence of additional climate policies. (IPCC 2000)
 How do we defensibly and efficiently translate global climate
 science to local impacts and wet weather planning action
Global Information
• Changing Climate science       Global-          Climate science
• General Circulation Models    regional          and scientists
• Emission Scenarios              scale           operate at
• lmpact assessment                               global scale
• IPCC Assessment Reports

                               Large gap
Local Concerns
• Defensible risk assessment
• Temp and precip change
• Catastrophic events            Local-
• Sea level change                                Impacts, planning, and
• Adaptation effectiveness
                                 scale            action are local
• Cost and timing
A solution: a modeling environment to bridge the gap between
global climate science and local impacts and action: SimCLIM
                            § SimCLIM—an integrated modeling
               Global-      system for assessing climate conditions
              regional      that influence risk and resilience for built
                scale       and natural infrastructure and operations
                            § Considers plausible, customized future
                            scenarios for water, sea level and coastal
                Local-      issues, human health, ecosystems,
               national     agriculture, transportation, energy, and
                scale       others
               Local-       § Incorporates local data for consideration
              national      of local impacts
  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
§ 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            Hurricane Isabel flooding, September 2003
                                             Photo Credit: Mark Young/The Journal Newspapers
  frequent storms
Projected Annual Precipitation (Reagan National Airport, DC)




                    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
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

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
 Detention systems can be multifunctional in downtown urban areas

Storage Pond used to Attenuate Storm Run-off   Dual-use Detention Storage Area in an Urban
in a New Development in Netherlands.           Community in Malmo, Sweden

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

Retrofitted rising flood barriers along
Orchard Road, Singapore.
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


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