Thompson Watershed Risk Assessment

A Disaster Mitigation Project on the Risks of Flood, Landslide and Debris Flows

• About the Risk Assessment
• Thompson Watershed Map
• Project Deliverables
• Key Project Results
• Risk Management Support for Communities
• Report & Background Materials

The 2018-2019 work of the Thompson Watershed Risk Assessment is complete, and the project deliverables are available.

The Fraser Basin Council encourages all orders of government with flood-related responsibilities in the Thompson River Watershed to make use of the project report, online geohazards map and other deliverables. These will interest regional districts, municipalities, First Nations governments, tribal councils, and provincial and federal government agencies.

Also see Thompson Flood Projects for a look at work in 2019-2020.

The blue waters of the Thompson River meet the sediment-rich brown flow of the Fraser River at Lytton – an iconic scene. Photo: Picture BC/Province of British Columbia

About the Risk Assessment

In 2018-2019 the Fraser Basin Council led 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 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.

Formally launched February 14, 2018, the risk assessment was managed by FBC’s Thompson Regional Office. Work completed in March 2019.

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. Over 200,000 people live in the Thompson watershed, which spans 5.6 million hectares.

The Thompson Watershed Risk Assessment fell within Stream 1 (Risk Assessment) of the National Disaster Mitigation Program.  Other streams were: Stream 2 (Flood Mapping); Stream 3 (Mitigation Planning); Stream 4 (Investments in Non-structural and Small Scale Structural Mitigation Projects). The assessment was funded in equal parts by Emergency Management BC and Public Safety Canada.

Thompson Watershed Map

The map Jurisdictions within the Thompson Watershed shows administrative and watershed boundaries. View a larger version (PDF).

Project Deliverables

Here are the final 2018-2019 deliverables for the Thompson Watershed Risk Assessment, as completed March 31, 2019 by BGC Engineering, with project coordination by the Fraser Basin Council.

Thompson River Watershed Geohazard Risk Prioritization Report.

This report summarizes the methodology and results of the risk identification and prioritization, with details in the appendices.

Read the report (PDF: 16 MB).

Interactive Geohazards Map of the Thompson Watershed

An online map is available view and interact with the results of the assessment. The map features layers on political boundaries, hydrology, hazard areas (by hazard type, hazard rating, priority rating and consequence rating), other hazards in the watershed, elements at risk, flood infrastructure, transportation routes & lifelines, and environmental values.

LEARN MORE

Geodatabase with Prioritized Geohazard Areas

This database is available to download. Download the database (Zipped GDB: 13 MB).

Excel Spreadsheet with Summary Statistics

Appendix J of the report is an Excel spreadsheet with summary statistics of results and attributes of prioritized geohazard areas. Download the spreadsheet  (XLSX: 2MB).

Key Project Results

BGC Engineering Inc. (BGC) carried out a clear-water flood, steep creek (debris flood and debris flow), and landslide-dam flood risk prioritization of the Thompson Watershed, with the support of Kerr Wood Leidal Associates (KWL), with funding provided by Emergency Management BC (EMBC) and Public Safety Canada under Stream 1 of the Natural Disaster Mitigation Program (NDMP, 2018).

BGC Engineering characterized and prioritized the flood, steep creek and landslide hazards in the watershed that might impact developed properties. The goal was to support decisions that prevent or reduce injury or loss of life, environmental damage, and economic loss due to geohazard events.

In the assessment, BGC Engineering identified and prioritized 6225 geohazard areas encompassing over 4,000 km 2 (7%) of the watershed. About 30% of the watershed’s population, 50% of assessed building values, 30% of business locations, and most of the major transportation routes are within or cross these geohazard areas.

The risk assessment provides the following information for the Thompson River Watershed:

• Identification and prioritization of flood and steep creek geohazard areas based on the principles of risk assessment (based on a consideration of both hazards and consequences)
• An online interactive map to view prioritized geohazard areas and supporting information
• An evaluation of the relative sensitivity of geohazard areas to climate change
• Gap identification and recommendations for further work.

Risk Management Support for Communities

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 in gaps in information.

Those with flood management responsibilities may draw on the information for one or more of the following:

• Operate under existing flood-related policies and bylaws, but base decisions on improved geohazard information and information management tools
• Review and potentially revise Official Community Plans (OCPs) and related policies, bylaws, and land use and emergency management plans
• Undertake flood resiliency planning, that is, “to prepare and plan for, [resist], recover from, and more successfully adapt to adverse events” (NRC, 2012)
• Develop a framework for geohazard risk management, including detailed hazard mapping, risk assessment, and mitigation planning
• Prepare funding applications to undertake additional work related to geohazard risk management within the Thompson River Watershed.

Local and First Nations governments are welcome to share these deliverables with their planning and development staff, and their emergency response staff. The online map can be used to explore the areas of risk identified, and detailed geospatial files and spreadsheets for use by mapping staff.  See the detailed report for specific recommendations.

Report & Background Materials

The final risk assessment report is available. Read the report.

An interim deliverable in the risk assessment was a report from BGC Engineering Inc., which set out a list of candidate project areas for which to pursue funding under the National Disaster Mitigation Program (NDMP) - Stream 2 in 2019/20. The funding would be used to complete flood mapping and acquire LiDAR data to support detailed flood mapping. See:

• NDMP 2019 Stream 2 Project Site Long List

Here are summaries and presentations from meetings of the project Advisory Committee

• Advisory Committee meeting - September 16, 2019 Meeting Summary
• Advisory Committee meeting - March 5, 2019 Meeting Summary
• Advisory Committee meeting - March 5, 2019 Presentation of Draft Results
• Advisory Committee meeting - August 16, 2018 Meeting Summary

The risk assessment initiative was launched February 14 at a Community-to-Community Forum in Kamloops, which brought together representatives of local governments and First Nations in the Thompson. Here is a forum summary and presentation slides (PDF):

• Summary: Community-to-Community Forum (February 14) on the Thompson Watershed Risk Assessment
• Project Overview
  Mike Simpson, MA, RPF, Senior Program Manager
• Flood Mitigation in BC
  Jasal Shah P.Eng., Director, Disaster Mitigation Branch, Emergency Management BC
• What the [Blank – Censored] Just Happened?
  Dwayne Meredith, P.Ag., Kerr Wood Leidal