Flood profiles and scenarios

A flood profile is calculated to forecast where and how high waters will rise in the event of a flood. Flood profiles are used in dike engineering and land use planning.

In partnership with the Fraser Basin Council and Northwest Hydraulic Consultants, the B.C. Government undertook a program of one-dimensional hydraulic modelling on the lower Fraser River. The overall objective was to generate an up-to-date design flood profile based on two scenarios:

1. The estimated flow during the 1894 Fraser River flood combined with high spring tide conditions
2. A 200 year winter storm surge with high tide combined with a Fraser River winter flood

View the original hydraulic model report from 2006:

• Fraser River Hydraulic Model Report (PDF, 15.2MB)

Current flood profiles

The original Fraser River hydraulic model was re-calibrated in 2008 to forecast water levels during the spring freshet.

The following model is the current, official Fraser River flood profile from Mission to the sea:

• Fraser River Hydraulic Model Update Report (PDF, 2.7MB)
• Fraser River Hydraulic Model Update Maps (PDF, 28.4MB)

A new hydraulic model was developed for the Hope to Mission reach of the Fraser River based on LiDAR and bathymetry data. The report compares design flood levels with recent dike crest elevation surveys.

The following model is the current, official Fraser River flood profile from Hope to Mission:

• Fraser River Design Flood Level Update – Hope to Mission (PDF, 8.7MB)

Return periods

Since the 1950s, the design of flood protection for the Lower Fraser Valley has been based on the large floods of 1894 and 1948. The 1894 flood was the design flood for the Fraser River dikes. A review was conducted on the magnitude of these two floods at the Hope gauging station and an updated flood frequency analysis was established.

This study concluded that the 1894 flood, previously thought to have a return period of approximately 160 years, would have a return period of approximately 500 years.

• Review of Fraser River at Hope Flood Hydrology and Flows (PDF, 1.2MB)

Climate change

The Fraser River hydraulic model has been used to develop a series of flood profiles to show changes in flood levels that would result from sea level rise and possible changes in peak flood flows, for the 170 km reach from Hope to the river mouth. The hydrological component of the project is attached as Appendix 1 of the report.

• Simulating the Effects of Sea Level Rise and Climate Change on Fraser River Flood Scenarios Phase 1 (PDF, 14MB)

An update to the report shows peak flow quantile projections at Hope by using the most recent global climate models and new emissions scenarios.

• Simulating the Effects of Climate Change on Fraser River Flood Scenarios Phase 2 (PDF, 4.3MB)

These climate change reports are not official policy, but represent current research into the effects of sea climate change, including sea level rise and its potential impacts on the Fraser River flood profile.