climate change workshop - cwwa/acepu · flood protection governance ... • requirement for all...

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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 ………………

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Thank you.

Questions?

Adrian Corlett, M.Eng. P.E.

(604) 438-5300

adrian.corlett@parsons.com