Between 2018 and 2023 the Fraser Basin Council supported projects to identify flood hazards and assess flood risk in the Thompson watershed in the Thompson-Nicola Regional District and in areas of the Cariboo Regional District. All floodplain mapping projects have built on previous work and have advanced flood hazard mapping to higher levels of detail. The reports and maps from these projects are available for reference and are intended to support governments in their flood management responsibilities.
An advisory committee — with representation from elected officials and staff from local government, First Nations and the Province of BC — provided guidance on the projects.
Please note and respect, as a condition of use, all limitations on use as set out within these reports and maps.
Aerial of Merritt area, December 2021 by Province of British Columbia
In 2022-2023 the Fraser Basin Council retained BGC Engineering Inc. to complete detailed floodplain mapping (Tier 3) for 15 watercourses and base level floodplain mapping (Tier 2) for three watercourses within the Thompson River watershed.
The total watercourse length mapped in 2022-2023 was approximately 230 km. The project included 13 floodplains subject to clear-water floods and two alluvial fans subject to steep creek (debris flood and debris flow) processes. Through the provision of detailed hazard maps and information, this study can help inform decision-making to reduce the risk of floods to communities.
Flood hazard maps developed for each site show the extent and characteristics (depth, velocity) of different magnitude floods for application in community planning, policy development and emergency response planning in areas subject to flood hazards. Implementation of updated flood hazard maps and flood construction levels (FCLs) for the study areas will lead to greater flood resiliency for communities within high flood hazard areas.
There is a final summary report on the project and 13 final reports, including maps, now available. These will be of interest to local governments and First Nations in the region.
The flood hazard mapping results and GIS mapping layers are also available digitally at www.cambiocommunities.ca.
Note: The Cambio Communities site is hosted by BGC Engineering and offers materials produced by BGC for the flood projects. Access is available to employees of local governments, First Nations or tribal councils in the region and employees of federal departments or agencies.
Following the November 2021 flooding of the Coldwater River, there was an urgent need to estimate the peak flow of the river to inform long-term reconstruction and flood mitigation. The primary objective was to establish a baseline estimate of the frequency-magnitude relationship for the Coldwater River at the City of Merritt.
In 2020-2021 this work was completed:
The 2019-2020 and the 2020-2021 flood hazard mapping projects were funded by the Union of BC Municipalities Community Emergency Preparedness Fund program.
Flood hazard mapping was completed in 2019-2020 to fill basic information gaps identified in the Thompson Watershed risk assessment. The mapping was at a base level, covering 478 square km across 11 floodplain sites in the Thompson-Nicola Regional District and one site in the Cariboo Regional District.
In 2018-2019 the Fraser Basin Council supported a risk assessment on flood, landslide and debris flows throughout the Thompson River watershed – including the North Thompson, South Thompson, Nicola, Bonaparte and Thompson Rivers (from Kamloops to the Fraser/Thompson confluence at Lytton).
The review came at an important time. For over two decades there have been high peak river flows in the watershed during spring freshet, as well as intense summer rainstorms with flash floods in some locations, and winter ice jams in others.
The risk assessment identified flood hazards, potential impacts, and community and infrastructure vulnerabilities as well as the overall flood risk profile for the region. The aim was to raise awareness, support mitigation planning and action, and reduce the magnitude of future emergencies. The project included compilation of data from previous risk assessments and work to fill information gaps so as to have a consistent, regional-scale approach across the watershed. Another component was to identify flood mapping and mitigation planning that is completed or underway.
This initiative brought together representatives of large cities, small municipalities, rural areas and First Nations communities – with the intention of identifying common risks and opportunities to work together across the watershed. The work was funded in equal parts by Emergency Management BC and Public Safety Canada.
The report and maps are intended to inform future planning and development, emergency response during flood and debris flow, and guide future work to fill gaps in information:
For more information, contact:
Alex de Chantal