qathet Regional District is studying coastal risks resulting from climate change to better understand the risks for public safety, infrastructure, environmental and economic values throughout the region.
The effects of climate change pose a serious potential threat to coastal communities. Over the coming years, sea level rise and more intense, frequent storms are predicted to increase the risk to people, property, and critical infrastructure located near the coast. Many coastal communities are recognizing the need to proactively plan for and mitigate these risks.
In collaboration with Tla’amin Nation and City of Powell River, the qathet Regional District retained Tetra Tech Canada Inc. to develop a series of coastal flood maps to better understand the flood and erosions risks for the qathet Region. The primary objective of the project was to develop a set of flood hazard maps showing areas that may be potentially inundated during a large flood event (200-year flood). A secondary objective was to analyze coastal geology and erosion potential. The qathet Regional District Coastal Flood Mapping was completed in two phases between June 2019 and April 2022.
To develop the coastal flood hazard maps, Tetra Tech analyzed the combined effects of sea level rise, tidal fluctuations, storm surge, wind and wave effects, and wave run-up for high priority areas along the coastline. Each report contains two set of coastal flood maps, one showing the coastal flood inundation area under present day conditions and the second showing the inundation area with consideration for 1.0 meter of sea level rise by the year 2100.
Tetra Tech used orthophotographic comparisons and erosion potential rankings based on shoreline type, back beach geology, slope angle, vegetation cover, storm exposure, and specific field observations to assess the qathet region’s coastal erosion potential.
The assessment highlighted the following key results:
- Erosion rates within the study area may range, on average, between approximately 0 and 0.4 meters per year.
- The stretches of shoreline assessed as having a relative moderate to high erosion potential are principally concentrated between Emmonds Beach and the Lois River on the mainland, and on Savary, Ahgykson (Harwood), and Texada Islands, where rock outcrop at surface is non-existent to minimal and storm exposure is greatest.
The maps included in the reports provide a more detailed picture of the potential flood and erosion risks to people, private property, critical infrastructure, and cultural and archaeological sites in high-priority locations. This project directly informed the development of the qathet Regional Coastal Flood Adaptation Strategy, which aims to reduce the risks associated with coastal flooding and erosion and increase the resiliency of coastal communities in the region. qathet Regional District will use the Coastal Flood Adaptation Strategy to guide and inform policy and decision-making related to land use, asset management, emergency preparedness, and community engagement.
The qathet Regional District Coastal Flood Map Reports can be accessed through the links below. Due to their large file size, the reports may take a while to download.
Please note that the coastal flood maps do not represent predicted shoreline positions or areas where flooding has previously occurred or will definitely occur in the future.
Further, the erosion ranking system used in the coastal geology and erosion potential assessment is designed to compare erosion potential between coastal locations and highlight areas of greatest risk to assist planning and mitigation efforts. It is also important to note that erosion is a complex process involving an interaction of variables that cannot be easily modelled. Therefore, the maps presented in the report do not represent where erosion will definitely occur in the future.
An Overview Flood Risk Assessment completed by Tetra Tech Canada Inc. in 2018 identified areas along the coast at the greatest risk for coastal flooding and erosion. The study analyzed the coastline from Lund to Saltery Bay, as well as Lasqueti, Texada, Ahgykson (Harwood), Savary, and Hernando Islands. The risk analysis addressed the impacts to people and society, environmental and cultural impacts, and local economic and infrastructure impacts. The report recommended completing more detailed modelling to properly assess the impacts and inform planning and mitigation work.
Storm surges can cause public safety concerns and property damage to low lying coastal areas.
Tsunamis
Our region’s geography offers protection from the devastating tsunamis generated by earthquakes in distant areas of the Pacific. Our coastline is still vulnerable to strong waves and tides resulting from local seismic events. Remember if you are near the seashore and feel an earthquake, it is important to move to higher ground as soon as the shaking stops.