Economics of Green Infrastructure in Adapting to Extreme Precipitation ERG: Arleen O’Donnell, Tess Forsell, Lauren Scott Horsley Witten Group: Nate Kelly and Kathleen McAllister NOAA Coastal Services Center Association of State Floodplain Managers Army Corps of Engineers, Institute of Water Resources Communities of Toledo Ohio and Duluth, MN Minnesota Sea Grant American Rivers
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Economics of Green Infrastructure in Adapting to Extreme Precipitation
ERG: Arleen O’Donnell, Tess Forsell, Lauren Scott Horsley Witten Group: Nate Kelly and Kathleen McAllister
NOAA Coastal Services Center
Association of State Floodplain Managers
Army Corps of Engineers, Institute of Water Resources
Communities of Toledo Ohio and Duluth, MN
Minnesota Sea Grant
American Rivers
Great Lake Pilot Projects: Duluth and Toledo
• Duluth - damages from rarer, high intensity events • Toledo - damages from frequent, low intensity events
• Experiencing precipitation more as rain, less as snow
• Projecting more intense precipitation in short durations, with extended periods of drought
3
Sidewalk Superintendent Assessing Damages
After the Sun Comes Out…
$55 million in costs for approximately 700 repair jobs from one storm event in 2012
We can’t afford to keep doing this
Communities interested in using green infrastructure to help reduce flooding,
but need to know…
• What are the options?
• What do they cost?
• What benefits do they provide?
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Project Objectives
• Identify green infrastructure flood reduction options and the costs and benefits of these options
• Create an approach to inform decisions about future infrastructure investments
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HOW MODELS WERE USED
•Historical climate data
• Projected climate data
CREAT
•Peak flow
•Runoff volume
•Base flood elevation
H&H Flood
damage costs
HAZUS
$
3. Estimate flood damages
Future land use
Damages to buildings, infrastructure, recreation, land
=
Scenarios: Estimate Flood Losses
2. How much runoff? 4. Losses
Current land use
1. How much rain? Historical Future
Scenarios: Estimate Flood Reduction
1. Rain
Historical Future
2. How much runoff with green infrastructure?
3. Estimate flood damages to buildings
Costs = green infrastructure implementation and maintenance ($)
Benefits = reduced damages ($)
$
4. Estimate costs & benefits
Benefit of this happening less?
Benefit of less homes damaged?
Benefit of being able to use the park?
Benefit of not having to fix damaged land?
What Did the Modeling Show Us?
• The probability that Duluth will experience damage from 100 year storm events will nearly double based on future growth (increased runoff) and future precipitation in 20 years
• Next Question: How can green infrastructure help reduce damage?
GI Cost
Change in Flooding
Overall Storage
GI Options What are the feasible GI options for the watershed?
What is the amount of storage desired to reduce flooding?
How does flooding change if the desired GI storage is implemented?
What would it cost to get the storage we need using different types of GI?
Our Approach to Assessing GI
Target: reduce peak discharge by
20% DULUTH
How much green infrastructure storage is needed to reach this target?