Flood Hazard Management on the Fraser River
PHOTO: The Fraser Basin Council (FBC) recently worked with local and regional governments in the installation of flood warning (dike crest) gauges on the lower Fraser. In Abbotsford, information on the project and the floodplain are posted for visitors to the dikes. FBC promotes flood hazard management and coordinated efforts by the responsible government agencies. Below is an overview of our work. For more information, visit our Frequently Asked Questions. |
Flood Risk on the Fraser
There are threats of flooding in almost any given year in British Columbia. Perhaps the greatest vulnerability to flood risk is in the floodplain of the Lower Fraser River. The Fraser Valley and other parts of the Fraser Basin have experienced two major floods of record, the largest in1894 and the second largest in 1948. Scientists predict that there is a one-in-three chance that a flood of similar magnitude will occur within the next 50 years.
Over 300,000 people now live in the Lower Fraser River floodplain. A major flood today would result in severe social, economic and environmental impacts. These include risk of injury and loss of life, billions of dollars in damage to private and public property, temporary loss of infrastructure and community services, disruption of business and trade, degradation of water quality and harmful impacts on fish and wildlife habitat.
Floodplain Maps
Where is the Lower Fraser Floodplain?
Click on map to view larger image
Above is an overview map of the Lower Fraser River, with flood plain areas coloured light blue. It is possible for flooding to occur outside the boundary area, and boundaries have been updated in a few locations following recent digital mapping projects requested by local governments in Mission, Kent, Harrison Hot Springs and Abbotsford. If you have questions about a given location in or near the floodplain, contacty your local municipal hall for information.
Maps with floodplain information:
* BC Ministry of Environment (floodplain maps)
* BC Ministry of Environment (Lower Mainland dike and emergency maps)
* BC Ministry of Environment (BC Water Resources Atlas, including flood protection works)
Many municipal governments have posted flood information pages and local floodplain maps on their websites. See our Frequently Asked Questions.
FBC's Role in Flood Hazard Management
The Fraser Basin Council has worked for many years to support government authorities that have responsibility for flood prevention, mitigation and recovery on the Fraser.
A predecessor of the Fraser Basin Council (the Fraser Basin Management Board) brought together an inter-governmental committee that published an "Integrated Flood Hazard Management Strategy." An integrated approach was necessary due to increasing population and development pressures on the floodplain, a decline in funding for floodplain programs, a lack of clear jurisdictional responsibility for flood management, and the recognition that floodplain management must be integrated with land use planning and environmental management.
In 1998 t he Fraser Basin Council initiated the Joint Program Committee (JPC) for Integrated Flood Hazard Management — a multi-party, consensus-based committee that brings together 36 federal, provincial, and local government agencies and organizations to address flood risks. While the FBC itself has no mandate or authority to oversee flood protection works or emergency services, we have been pleased to play a lead role in supporting government authorities through the coordination, facilitation and secretariat of the JPC.
In collaboration with local, regional, provincial and federal governments, the Fraser Basin Council has worked on a number of initiatives, including the development of flood hazard management tools and reports on flood protection works and floodplain management.
2006 Study to Update the Fraser Flood Profile
Many Fraser Valley and Lower Mainland communities are protected by over 300 km of Fraser River dikes between Agassiz and Delta (including the sea dikes). Almost 250 km of these dikes were reconstructed by the federal-provincial Fraser River Flood Control Program between 1968 and 1995.
In 1969 by the federal Inland Waters Directorate established dike design levels based on the estimated flood water levels plus 0.6 m of freeboard. At that time, authorities relied on high water marks from the two largest floods on record, in 1894 and 1948, and limited computer modelling, to create the flood profile. Other flood management plans and decisions also used the 1969 profile. Engineers of the day did not have access to the sophisticated data-gathering and analytical tools that are available today, however. It became apparent that a new study was needed to bring the flood profile up to date.
In 2003 the Fraser Basin Council (FBC) and the BC Ministry of Environment initiated a multi-year study to develop a hydraulic model of the lower Fraser River to update the design flood profile. The study, managed by the Fraser Basin Council, was intended to develop an up-to-date design flood profile based on (a) the 1894 Fraser River freshet flood combined with spring high-tide conditions (Fraser freshet profile), and (b) a one-in-200-year winter storm surge flood with winter high tide conditions combined with a Fraser River winter flow (the winter storm surge profile).
In November, 2006 the results of the study were released. The flood profile computed by the Lower Fraser hydraulic model is higher than the original 1969 flood profile. As a result, the study found that widespread dike overtopping and dike failures would occur throughout the Lower Fraser River should there be another major flood equivalent to the 1894 flood of record. In such an event, diking systems from Chilliwack and Kent to Surrey and Coquitlam would be overtopped at one or more locations, and the Delta dike at Fraser Shore would be overtopped at one location. Freeboard for a winter storm surge flood would be inadequate in Delta and Richmond.
The Province of BC accepted the results of the FBC study and adopted a new flood profile for dike design and construction. In March, 2007 the Province provided $33 million for diking authorities throughout BC to undertake urgent flood mitigation works that could be completed prior to the spring freshet .
The Fraser Basin Council remains committed to encouraging government authorities to make flood hazard management a priority in the long term.
To see the results of the Lower Fraser hyraulic model, see News Release/Backgrounder and Summary of Results.
The full study, in four volumes, has been posted on the BC Ministry of Environment website.
For more information, contact Program Manager Steve Litke at (604) 488-5358 or slitke@fraserbasin.bc.ca.
2008 Review of New Roles and Responsiblities in Flood Hazard Management
In 2007 the Fraser Basin Council began a review of floodplain management policies and practices in BC, with funding from the BC Ministry of Environment. The review followed provincial legislative changes in 2003 and 2004 that altered the respective roles and responsibilities of the Province of BC and local governments in flood hazard management. Most notably, local governments no long require approval from the Ministry of Environment in establishing floodplain bylaws and subdivision approvals in flood hazard areas.
The purpose of FBC’s review was to learn what changes local governments have made under the amended legislation, what is working well, what challenges or concerns exist, and what improvements are needed. Local governments and others involved in making land use decisions in flood hazard areas were invited to participate in an online survey. The final report on this review is now avalable: Flood Hazard Area Land Use Management.
Other Flood Hazard Management Projects
Although nature controls the timing and severity of flood events, communities can reduce the extent of flood damages by managing flood protection works, preparing emergency flood plans, and introducing floodproofing measures and floodplain bylaws. Combined, these activities provide an integrated approach to flood hazard management.
In its 2005 -2006 fiscal year, the FBC undertook the following flood hazard management projects and initiatives, with financial support primarily from the BC Ministry of Environment:
- Dike crest gauges: Installation of flood warning gauges (dike crest gauges) in various locations throughout BC, in cooperation with 16 local and regional partners.
- Digital floodplain maps: Digital floodplain maps for the communities of Kent-Agassiz, Harrison Hot Springs, Abbotsford and Mission, as requested by local governments.
In addition, the FBC has been involved in the following :
- Education and outreach – Published and distributed maps, educational brochures, newsletter articles and online flood information. Presented to local government in many communities on the 2006 flood study and its implications, and did extensive media outreach.
- Participation in flood management initiatives – Participated in flood management meetings, workshops and seminars and submitted consensus-based recommendations in relation to the Provincial Floodplain Management Program Review, the National Disaster Mitigation Strategy, the Union of BC Municipalities and the Lower Mainland Municipal Association and graduate research on flood management approaches.
Contact:
Steve Litke, Program Manager
Integrated Flood Hazard Management
Fraser Basin Council
1st Floor - 470 Granville St.
Vancouver, BC
V6C 1V5
Tel: (604) 488-5358
Fax: (604) 488-5351
Email: slitke@fraserbasin.bc.ca
Terms and Definitions
For a better understanding of floods and flood hazard management, take a look as some common terms and definitions.
Brief History of Fraser Floods
The largest Fraser River flood on record occurred in May of 1894 when rapid snowmelt caused river levels to rise dramatically, triggering flooding from Harrison to Richmond. The flood was massive; however, property damage was limited because settlement was sparse. The next largest Fraser flood of record occurred in 1948. Due to increased development and population growth within the floodplain, the impacts were much greater than in 1894, including:
- Evacuation of 16,000 people
- Damage or complete destruction of 2300 homes
- 1500 residents left homeless
- Recovery costs of about $150 million (current values).
Since 1948 the Fraser River has not had a flood of this magnitude, although there have been many close calls. Since the early 1970s, the joint federal-provincial Fraser River Flood Control Program has spent nearly $300 million improving and expanding flood protection through an extensive diking system. Today in the Fraser Basin, there are about 600km of dikes, 400 floodboxes and 100 pump stations to protect communities and infrastructure from flooding. For a recap of recent flood hazard management initiatives, see Recent Study to Update the Lower Fraser Flood Profile and Other Flood Hazard Management Projects above.
Where to go for more information
Here are some helpful sites for information on flood risks in BC and emergency preparedness. Also see our Frequently Asked Questions.
BC Ministry of Environment (Water Stewardship Division)
River Forecast Centre - BC Ministry of Environment
Provincial Emergency Program (PEP)
Public Safety and Emergency Preparedness Canada
Emergency Preparedness Information Exchange (EPIX)
Brochure - Floodproofing in Historic Settlement Areas
This brochure provides useful information to help understand the benefits of floodproofing, the challenges associated with floodproofing in historic settlement areas, practical floodproofing design options, and a list of flood resistant building materials:
Floodproofing Historic Settlement.
