qathet Regional District Coastal Flood Mapping

qathet Regional District / Powell River, BC, Canada
Submitted by:
Daniel Potts
Hydrotechnical Engineer at Tetra Tech
Project URLs:

Project Description

Tetra Tech is working with the qathet Regional District (qRD) to prepare coastal flood maps for emergency management, community planning and public information. The study area includes about 350 miles of coastline on the Salish Sea ranging from steep, rocky shores to low, sandy beaches. Human uses of the coastline include nature reserves, recreation, industry and residential waterfront, both urban and rural. Funding for the first phase, an overview-level risk assessment of coastal hazards, was provided by the National Disaster Mitigation Program. Funding for the second and ongoing phase, assessment of coastal flooding and erosion potential, is from Emergency Management British Columbia.

The project scope involves the collection and synthesis of observations from regional tide and wind stations, field geological surveys, wave buoys, and historic aerial imagery. Nearshore bathymetry and coastal Lidar data were collected to support detailed flood mapping. Numerical modelling by the project team generates predictions of extreme wave run-up elevations with and without sea level rise. Future mean sea levels and extreme wind intensities were interpreted from modelling and research by others.

Detailed flood mapping (1:5000 scale) for present and future extreme conditions was prepared in GIS format, and is expected to be shared with the public by municipal officials.

Key Successes

Identified areas of greatest coastal risk; in those areas, made maps of potential inundation at flood construction reference plane


Collection, processing and merging of bathymetry and Lidar data
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