British Columbia Extreme Flood Project

Last updated on November 6, 2023

Photo of WAC Bennett Dam taken in August, 2013

The British Columbia Ministry of Forests, Water Management Branch, Dam Safety Section initiated and managed a project to supplement available hydrology and hydrometeorological information. The goal was to improve the quality, confidence, and accessibility of baseline data about the magnitude and uncertainty of extreme flood events in B.C. This information will be useful for the design of dams, spillways, and dikes as well as linear infrastructure stream crossings.

The guidance and associated products developed for the entire province (the Project) are available in EcoCat's Ecological Reports Catalogue and include:

  1. Regional Flood Frequency Analysis (RFFA) - ID 59125
  2. Regional Precipitation Frequency Analysis (RPFA) – ID 59231
  3. Probable Maximum Precipitation (PMP) – ID 59232
  4. MetPortal Application Guidance for Freshwater Dams – ID 59799

The Project hydrometeorological deliverables are available from the MetPortal from DTN and include:

  • Probable Maximum Precipitation (PMP) estimates for synoptic-scale storms at the 24-, 48-, 72-, and 96-hour durations and key watershed area sizes for a series of transposition points across BC
  • Probable Maximum Storms (PMSs), the storm spatial and temporal patterns that produced the PMP at a key watershed area size and duration of interest at each of the transposition points to convert the PMP estimates into input for a hydrologic model
  • Point precipitation-frequency estimates for the 24-, 48-, 72-, and 96-hour durations

The Project flood analysis deliverables include:

  • Frequency analysis reports for 816 hydrometric stations in the study region
  • Assignment of flood regions based on the Ecological Land Classification system
  • Regional flood prediction regression equations for ungauged basins
  • Guidance on estimating the magnitude of extreme flood quantiles

Historical flood-related information obtained from local and regional archives was incorporated into the flood frequency analysis of selected streamflow gauges and a methodology for validating such historical information was proposed. In addition, guidance documents have been completed for practitioners to utilize when completing flood studies with the hydrometeorological and flood flow analysis information.

For more information about this project, contact:

Jeff Grass
Senior Dam Safety Project Manager
Dam.Safety@gov.bc.ca