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Lower Mainland
Flood Management Strategy Maps

Important:

The regional flood maps in this section were developed in Phase 2 of the Lower Mainland Flood Management Strategy initiative.

These maps are based on modelling a limited number of Fraser River and coastal flood scenarios and are for regional planning purposes ONLY.  These maps are NOT projections of whether or when future flood events may occur and are not of sufficient detail for local-level flood planning or analysis. Moreover, these maps DO NOT TAKE INTO ACCOUNT various measures that local governments or other flood authorities may take to avoid or reduce flooding in a high water or flood event, such as:

  • Current and future flood risk reduction measures, including diking improvements
  • Emergency preparedness and response measures, including emergency diking, that may be undertaken by local governments in the event of a flood event.

Always check with your local government for local flood maps, flood risk reduction and emergency response plans specific to your community.

The regional maps in this section are helpful to show the potential scenarios for Fraser River and coastal flooding in the region in present day, 2050 and 2100 if no flood risk reduction measures are taken. The modelling and mapping work reinforces the importance of local and regional-scale planning and long-term investments in flood risk reduction.

The maps in this section:

  • Should NOT be used for officially designating flood hazard areas, establishing flood construction levels, or designing dikes or other structures. Government authorities require more detailed, local mapping and analysis to designate flood hazard areas for these purposes
  • Do not show flooding from other rivers, streams, and creeks in the region, except backwater effects from a Fraser River flood
  • Show the maximum flood depth (highest level during the flood). Flood depths will vary by location and stage of flooding
  • Are based on the Lower Fraser River 2D Flood Model unless otherwise stated
  • Assume that existing dikes are present unless otherwise stated. In scenarios where the modelled flood level is higher than the dike, the maps account for dike overtopping (i.e., water rising above the height of the dike and flooding the other side). But dikes can fail in other ways, such as piping and seepage, before they are overtopped during a flood—these are not accounted for in these maps. To see illustrations of how select dike breaches might affect flooding in the Lower Mainland, see dike breach scenario maps below
  • The dike breach maps are illustrative examples only. They are not predictions of where a flood event (either dike overtopping or breaching) would occur in the Lower Mainland.

The animation videos in this section:

  • Show the progression of flooding over a 21- or 22-day period
  • Provide a plan view of flood depths, accounting for tide cycles and dike overtopping (but not dike breaching).

Read about it:

Fraser River Freshet (Spring) Flood Scenarios – Present Day

The five maps below show flood depths and extents for Fraser River freshet floods of increasing magnitudes based on the historical record and today’s climate (present-day conditions).

  • 1894 freshet flood event. [Map PDF] [Animation] The 1894 Fraser River flood is considered to be slightly more severe than the estimated 0.2% AEP flood today. This is considered the “design flood” to inform dike design and construction along the lower Fraser River dikes.

Fraser River Freshet (Spring) Flood Scenarios – Year 2050 with Climate Change

The two maps below estimate flood levels under projected climate change conditions in 2050. The conditions include 0.5-metre sea-level rise and changes in peak river flows. A 1% AEP flood in 2050 will be more severe than a 1% AEP flood today. Similarly, a 0.5% AEP flood is projected to be more severe in 2050 than today.

Fraser River Freshet (Spring) Flood Scenarios – Year 2100 with Climate Change

The three maps below estimate flood levels under projected climate change conditions in 2100. The conditions include 1-metre sea-level rise and changes in peak river flows. A 1% AEP flood in 2100 will be more severe than a 1% AEP flood today.

Coastal Storm Surge (Winter) Flood Scenarios within the Fraser River Flood Hazard Area – Present Day 

These two maps show the effects of a coastal storm–caused flood within the Fraser River flood hazard area only. These maps exclude flood hazard areas in the Lower Mainland outside of the Fraser River flood hazard area, such as Boundary Bay, Burrard Inlet, Lions Bay, and Squamish.

Coastal Storm Surge Flood Scenarios – Present Day and with Sea-Level Rise

The two maps produced for these coastal flood scenarios are based on a simplified approach through extending the estimated ocean flood level across the land. The 2D model was not used for these maps. They assume there are no dikes and do not consider localized wind and wave effects, subsidence/uplift, or the tidal cycle. In some cases, more accurate, detailed modelling and mapping may be available from municipalities.

  • 0.2% AEP coastal storm surge flood with current sea level. [Map PDF]
  • 0.2% AEP coastal storm surge flood with 1m sea-level rise. [Map PDF]

Dike Breach Maps

Dike breaches were simulated as part of the Lower Fraser River 2D flood modelling project for the Lower Mainland Flood Management Strategy to develop an understanding of potential flood extents, flood progression, depths and hazard.

The simulations show how severe a flood scenario can be, how quickly it can occur, and why it is important to evacuate early, before a potential dike breach. For emergency planners, it is helpful to see the timing and extent of flooding, water velocity, and flow direction and progression when developing emergency plans. The simulations show that flooding from a dike breach can progress quickly, cutting off evacuation routes and reaching residents, livestock and/or infrastructure within a few hours.

The dike breach locations were selected to provide a range of results, not necessarily because they are more likely to breach. The locations were selected based on criteria including: the breach is capable of being modelled and may create significant local or regional impacts. The breaches are hypothetical and modelled for learning purposes only. Please refer to the notes on each map for more information.

For the following maps, the flood scenario modelled is the 1894 freshet flood event, unless otherwise stated.

  1. Vedder Canal [Map PDF]
  2. Upstream Kent [Map PDF]
  3. Upstream Chilliwack [Map PDF]
  4. Upstream Pitt Meadows [Map PDF]
  5. Queensborough [Map PDF]
  6. Upstream Delta (0.2% AEP freshet flood with 1m sea-level rise) [Map PDF]
  7. Chilliwack and Vedder Canal [Map PDF]
  8. Kent, Chilliwack, Vedder, and Matsqui (0.5% AEP freshet flood) [Map PDF]

Flood Risk and Vulnerability Maps

In 2015, an assessment of flood vulnerability was developed for the Lower Mainland Flood Management Strategy initiative. Flood vulnerability and risk maps were produced to show coastal and Fraser River flood extents in relation to critical infrastructure and facilities, including emergency operations centres, hospitals, schools and airports.

See the 2016 Lower Mainland Flood Vulnerability Assessment maps (PDF, large file, maps on pages 71–82, 85–86).

Lower Mainland Flood and Environment Atlas

The Lower Mainland Flood and Environment Atlas was developed as part of the Lower Mainland Flood Management Strategy. This atlas contains flood extents for the Lower Mainland for select flood scenarios along with a range of environmental values and features along the lower Fraser River and coastal foreshore areas. The atlas is a resource when decision makers are considering potential environmental benefits (and adverse impacts) of floods as well as flood risk reduction projects or policies. The flood levels shown on this portal are based on the 2015 Analysis of Flood Scenarios and mapping from the 2016 Lower Mainland Flood Vulnerability Assessment.