Flood Management Study

Serious floods in the City of Courtenay in 2009, 2010, and again in 2014 highlighted our community's vulnerability, and the need to improve existing levels of flood protection.

The City received funding from the Building Canada Fund - Communities Component, Flood Protection Program. With this funding, the city developed updated floodplain mapping with high-resolution orthographic (aerial) photos, hydrologic modelling, and completed an Integrated Flood Management Study.

Consultants McElhanney Engineering partnered with KWL Consulting Engineers and HB Lanarc to develop a hydrological model forecasting flood levels for various climactic conditions and different flood protection configurations.

Reports & Publications

May 4, 2015 Presentation to Council:

The model reviewed three options:

  1. Tsolum River flood wall
  2. Ring dike
  3. Partial ring dike and floodway

 Option 1: Floodwall

  • Construct floodwall to provide protection for smaller more frequent events (20 year events)
  • Ryan Road area will continue to flood during extreme (200 year) events
  • Cost: $750,000

Option 2: Ring Dike/Floodproofing

  • Raise Old Island Highway and Highway 19A
  • Provides improved flood protection for Ryan Road commercial area
  • Requires "managed retreat" or flood proofing of properties within floodplain outside dikes
  • Allows overland flooding across Comox Road into agricultural fields
  • Cost: $5,851,000

Option 3: Partial Ring Dike

  • Similar to Option 2 in raising Old Island Highway and Highway 19A
  • Creates controlled overland flooding on Comox Road - Proposed Floodway
  • Reduced area of flood protection for Ryan Road neighbourhood
  • Requires "managed retreat" or flood proofing of properties within floodplain outside dikes
  • Allows overland flooding across Comox Road into agricultural fields
  • Cost: $5,456,000

Other benefits and costs include:

  • Ancillary mitigation/compensation costs. No negative impacts upstream/downstream
  • Environmental costs to mitigation measures are viewed as minimal because events are infrequent and short duration
  • Benefit to tangible property assets (up to $40 million). Flood emergency costs $500,000 per occurrence

Report Recommendations

The Integrated Flood Management Study recommends the following:

  • Continue to protect the majority of the floodplain in compatible uses that will accommodate floods
  • Consider floodwall (option 1) as an interim solution to an overall flood mitigation strategy as a medium term solution (20 to 50 years)
  • Review emergency plans for today, year 2100 and 2200
  • Identify where and when additional diking might be warranted for consideration - longer term solutions
  • Evaluate diking options including financial and cost-sharing analysis
  • Update regulation for Flood Construction Levels (FCL) and flood proofing of buildings
  • Undertake long-term climate change adaptation planning in coordination with senior governments