building resilience to climate change through stormwater
TRANSCRIPT
Building resilience to climate change through stormwater management REBECCA ESSELMAN ● [email protected]
HURON RIVER WATERSHED COUNCIL ● WWW.HRWC.ORG
How is climate changing?
Climate Change in the Great Lakes
www.glisa.umich.edu
Communicating Global Challenges at the Regional, Local Scale
Global trends are more certain than regional trends.
Natural variability plays a larger role at the regional scale.
Local changes in land use can alter the severity of climate change impacts.
What has Changed? Temperature
Averages
Extremes
Seasonality
Precipitation
Averages
Extremes
Seasonality
Scientists often discuss changes in terms of averages, but our environments are managed in terms of timing and extremes.
Rising Average Temperatures
2.0°F Observed 1900-2012
3.5 - 6°F Projected 2041-2070
Longer Frost-free Season
From the 3rd National Climate Assessment, 2014
9-10 Days Observed 1958-2012
1-2 Months Projected 2071-2099
Observed Extreme Precipitation
Following methodology from Groisman et al, 2005, updated.
The amount falling in the heaviest 1% of precipitation events increased by 37% in the Midwest from 1958 to
2012.
Declining Great Lakes Ice Cover
Lake Superior is warming twice as fast as nearby air.
Lake Superior could have little open-lake ice cover during a typical winter by mid-century.
Wang et al., 2012
Austin and Colman, 2007
71% 1973-2010
Average Great Lakes Ice Coverage
glisa.umich.edu
• Southeast lower Michigan climatic division (shown here)
• Climatologies based on station data • Change maps • National Climate Assessment and regional reports
• GLISA Grant Program
Magnitude of change in risk for natural hazards for the region
Implications for stormwater management
With increased extreme precipitation events, we see more intense, flashy runoff resulting in greater overland and concentrated flows. • flooding more places more often • erosion • infrastructure failure • service disruption • public health in the case of CSOs
Strategies • Green Infrastructure • Community planning and regional
collaborations • Education on flooding and mitigation • Inventory current infrastructure • Acquire and manage ecosystems to regulate
runoff • Monitor weather and surface water conditions
• Adopt NOAA Atlas 14 storm definitions when
designing stormwater infrastructure
Changing Precipitation Event Definitions
Atlas 14 database http://hdsc.nws.noaa.gov/hdsc/pdfs
Implications for system design 1-Yr 2-Yr 5-Yr 10-Yr 25-Yr 50-Yr 100-Yr
1-hr 0.88/0.969 [10%]
1.06/1.14 [8%]
1.29/1.44 [12%]
1.47/1.70 [16%]
1.69/2.07 [22%]
1.87/2.38 [27%]
2.05/2.69 [31%]
12-hr 1.63/1.82 [12%]
1.97/2.06 [5%]
2.39/2.50 [5%]
2.72/2.90 [7%]
3.13/3.54 [13%]
3.46/4.09 [18%]
3.79/4.68 [23%]
24-hr 1.87/2.09 [12%]
2.26/2.35 [4%]
2.75/2.83 [3%]
3.13/3.26 [9%]
3.60/3.93 [9%]
3.98/4.50 [13%]
4.36/5.11 [17%]
Outlet restrictions for detention ponds
Common LOS for storm conveyance design FEMA flood ins.
and floodplain boundary
detention basins/ outlet structures
Implications for Planning Our floodplains are expanding. This should be reflected in how we develop and where.
Reconsider locations of critical facilities
Likely to see increase in Repetitive Loss Properties
Insurance burden on private property owners and municipalities
Revisit other aging infrastructure – dams, waste water treatment plants, etc.
How one city is changing… Ann Arbor’s climate informed stormwater management
Code change to follow County’s new stormwater rules.
Created Stormwater Model using Atlas 14 data See impacts of different storm events and potential future events Helps identify problem areas and optimize solutions Mapped floodplain with revised 100 year storm (5.11”) and compared
to FEMA floodplain (4.36”)
What the future holds Priority projects make it into Capital Improvement Plan Making the case for higher stormwater fees Ordinance 1’ above 500 year flood.
Funding the solutions Stormwater Utility – fee for use of stormwater system. Creates funds for infrastructure upgrades
Similar to water and wastewater, all developed properties place a quantifiable demand on a storm sewer system
Taking Stormwater Utilities to the State - Stormwater Management Finance group crafting a proposal to enable the formation of stormwater utilities consistent with the Bolt decision
leveraging resources needed to secure legislation
gaining recognition of the problem and energizing groups around the solution
Thank you
Rebecca Esselman [email protected]
Project page www.hrwc.org/climate-resilient-communities GLISA resources www.glisa.umich.edu