climate change workshop - cwwa/acepu · flood protection governance ... • requirement for all...
TRANSCRIPT
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CWWA 16th Canadian National Conference on Drinking Water
Climate Change WorkshopOttawa, October 28, 2014
Sea Level Rise - The Cost of Staying Dry
Adrian Corlett, M.Eng, PE
Parsons
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• Population 4.5 million
• 95 million hectares
• 29 Regional Districts
• 161 Municipalities
• 197 First Nation Bands
British Columbia
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“Road closure” Chilliwack RiverNovember 1989 • Coastal flooding
• Storm surge• Tsunami• Sea level rise
• River and stream floodplains
• Spring freshet
• Rainfall and rain-on-snow floods
• Erosion
Flood Hazards in BC
Boundary BayDelta February 2006
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Flood Protection Governance
Local – Municipalities, Regional Districts and Diking Districts• Statutory obligation, ownership, planning, response
Provincial:
• Ministry of Justice: Emergency Management BC• Coordination, support for mitigation, preparedness, response and recovery,
Flood Protection Program
• Ministry of Forests, Lands and Natural Resource Operations• Dike Safety Legislation, Provincial Dike Safety Program, Standards
• Water Stewardship, Water Act, Dike Maintenance Act
• Ministry of Community, Sport and Cultural Development• Land use planning, Community Charter, Local Government Act
Federal:• First Nations, Environmental and Fisheries
• Disaster Mitigation Funding – Building Canada Fund
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Recent Guidelines – Sea Level Rise
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Further work underway to determine Joint Probabilistic interaction
Recent Guidelines – Sea Level Rise
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1912
2010
2100
Sheltered Exposed
2010
2100
Recent Guidelines – Sea Level Rise
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Geological Survey of CanadaSeismic Hazard Map
High Seismic Hazard
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High Seismic Hazard
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• Developed by Golder Associates in 2011 for MoFLNRO
• Applies to High Consequence Dikes
• Sets maximum allowable displacements
• Requirement for all current and future dike improvements
Recent Guidelines - Seismic
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Scope: To estimate the cost of adapting to sea level rise by 2100
What do we protect against? • Hazard defined by 2011 Sea Dike Guidelines
What standards apply?• 2011 Sea Dike Guidelines • 2011 Seismic Guidelines for Dikes
How much will it cost? • Goal of the project.
Case Study
Cost of Adaptation - Sea Dikes & Alternative StrategiesBC Ministry of Forests, Lands and Natural Resource Operations,
Delcan, October 2012
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Metro Vancouver
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• 75,000 hectares protected by 365 km of dikes
• 58 dike rings managed by 29 diking authorities
• 500,000 people live and/or work in floodplain
• 2 million people depend on infrastructure within floodplain
• Re-occurrence of 1894 flood with dike failures would cause tens of billions of dollars of damage
Metro Vancouver – What’s At Risk?
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Metro Vancouver – What’s At Risk?
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Metro Vancouver – What’s At Risk?
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Metro Vancouver – Sea Dikes
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• 250 km of shoreline (125 currently diked)
• 13 municipalities and dike authorities
• Many different existing conditions – coastal, river, urban, rural
Study Area
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• Divide 250km into 36 reaches
• Develop list of possible protection options
• Select protection option for each reach
• Estimate the cost of the chosen option
Scope and Methodology
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Protection Options
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Protect • Super dikes
• Demountable structures
• Earth dikes
Protection Options
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Protection Options
Protect • Barrier islands
• Dunes
• Marshes
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Accommodate• Flood proofing
• Secondary dikes
• Emergency response
Protection Options
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Protection Options
Accommodate• Room for the River – the Dutch approach
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Protection Options
Retreat• Managed retreat
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Protection Options
Avoid• Planning and development controls
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• Initial elimination
• Stakeholder workshops
• Assess possible options
• Select one option per reach
Selection of Options
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• Protection options favoured for most reaches
• Typically traditional dikes
• Managed Retreat selected for one reach
• Breakwater and surge barrier combinations for several
Results
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The Cost
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The Cost
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• Limited study area – only Metro Vancouver area
• ‘Class D’ estimate
• Only using 36 reaches requires significant generalization
• Costs do not include operations and maintenance
• Seismic Guidelines are evolving – estimate is for current requirements
Limitations
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Next Steps: Long-Term Planning
• Long-term dedicated regional programs are required to 2100 and beyond.
• Adaptation and mitigation to be based on Regional Flood Protection Plans.
• Standardized risk-based design flood level elevations for sea & river dikes (ie. 1:500, 1:1000) should be established as part of an updated floodplain mapping program.
• Funding models must recognize the varying financial capacities of local government and diking districts.
Effective flood mitigation requires time to plan, design and implement ………………
