Understanding flood risk

Flooding is a common occurrence in B.C. Numerous conditions contribute to flooding, either acting alone or in combination with other flood conditions to result in more severe flood events.

Floods can be caused by: 

• Climatic conditions (for example, intense rainfall, rain on snow, ice jams, rapid snowmelt, storm surges)
• Geomorphic processes (for example, debris flows, tsunamis, landslides)
• Structural failures (for example, dike failure, dam failure)
• Human activity (for example, logging, dam releases)

The most common occurrences of flooding in B.C. are the result of: 

• Heavy rain and rain on snow (flash flood) 
• Freshet (melted snow) 
• High tides and strong winds (storm surge) 
• Ice jams 

Floodplain mapping

Floodplains are areas that experience periodic flooding from nearby bodies of water. Floodplain mapping is an important first step in understanding where floods may occur and in developing a flood hazard management plan.

Understanding flood risk and land use 

In 2024, the B.C. government commissioned a report to explore how growing housing needs impacts flood risk in areas prone to flooding. An addendum from 2026 was added to the report and reflects recent updates since the report was completed.

You can read the addendum and entire report or a summary:

• Understanding the Potential Flood Risk of Current and Future Provincial Land Use Policy: Policy Review and Case Study Analysis
  • Full report (PDF, 2.7MB)
  • Summary (PDF, 619KB)