Lower Mainland Flood Maps

• About the Maps
• Flood Modelling & Mapping Primer
• Important: Use of the Maps
• Lower Fraser River Freshet Flood Scenarios Maps
• Learn More

About the Maps

The 2019 Lower Fraser River 2D Flood Modelling and Mapping Project is a major component of the Lower Mainland Flood Management Strategy. The flood model estimated the extents and depths of flooding from a range of flood scenarios.

The Fraser River Freshet flood depth maps linked below are intended to help with regional flood planning. In particular, the maps help those with responsibilities for flood management:

• Better understand current and future flood hazards
• Advance work on risk assessment to help prioritize high-risk areas
• Evaluate flood risk reduction options, and
• Enhance emergency preparedness and response planning.

Flood Modelling & Mapping Primer

An overview of the mapping project can be found in Flood Modelling and Mapping in BC's Lower Mainland: A Project Primer.

Important: Use of the Maps

These regional flood hazard maps are based on modelling a limited number of flood scenarios and are for regional planning purposes only. These are NOT projections of whether or when future flood events may occur and are not of sufficient detail for local flood planning or analysis.

The maps in this section:

• Should NOT be used for officially designating floodplains, establishing flood construction levels, or designing dikes or other structures. Government authorities require more detailed, local mapping and analysis to designate floodplains 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 the following maps.
• Must identify the the Fraser Basin Council (on behalf of the Lower Mainland Flood Management Strategy partners) as owner of the maps.
• May NOT be used commercially in any way without permission of the Fraser Basin Council
• May NOT be modified in any way without permission of the Fraser Basin Council.

Lower Fraser River Freshet Flood Scenarios Maps

Note: While reduced in size for web access, the PDF map files are large and may take few moments to view in your browser or download.

Fraser River Freshet (Spring) Flood Scenarios – Present Day

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

• 2% AEP (50-year) freshet flood. [Note Corrected map to be added]
  
• 1% AEP (100-year) freshet flood. [Map PDF]
• .5% AEP (200-year) freshet flood. [Map PDF]]
• .2% AEP (500-year) freshet flood. [Map PDF]
• 1894 freshet flood event. [Map PDF] The 1894 Fraser River flood is considered to be slightly more severe than the estimated 0.2% AEP (500-year) flood today. This is considered the “design flood” to inform dike design and construction along the lower Fraser River.

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 (100-year) flood in 2050 will be more severe than a 1% AEP flood today. Similarly, a 0.5% AEP (500-year) flood is projected to be more severe in 2050 than today.

• Year 2050 1% AEP (100-year) freshet flood with 0.5m sea level rise. [Map PDF]
• Year 2050 .2% AEP (500-year) freshet flood with 0.5m sea level rise. [Map PDF]

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 (100-year) flood in 2100 will be more severe than a 1% AEP flood today.

• Year 2100 1% AEP (100-year) freshet flood with 1m sea level rise. [Map PDF]
• Year 2100 0.5% AEP (200-year) freshet flood with 1m sea level rise. [Map PDF]
• Year 2100 0.2% AEP (500-year) freshet flood with 1m sea level rise. [Map PDF]

Higher resolution versions of the maps (large files) are available on request.

More Information

For more information about the mapping project and the maps, please contact:

Steve Litke, Senior Program Manager
Lower Mainland Flood Management Strategy
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