Located at the head of Howe Sound, Squamish is frequently exposed to floods and flood-related hazards such as erosion and storm surge. In 2017, Squamish developed an Integrated Flood Hazard Management Plan (IFHMP) to map flood risk areas. Based on guidance from the provincial government, the plan assumes that by 2100, climate change will raise sea levels by 1 metre and peak river flows will increase by 10%. The results from the IFHMP reaffirmed that Squamish is at risk from coastal flooding and determined that the existing dikes will not provide protection during a 200-year return period flood.
In 2019, a Climate Lens Resilience Report was conducted as part of Infrastructure Canada’s funding requirements to determine how climate change would affect the sea dike design proposed by the IFHMP. A PIEVC Practitioner Risk Assessment approach was used to determine the impact of climate change during dike construction (2020) and throughout the dike’s service life (2100). Six climate change parameters and two cumulative events were used; wildfire air quality, extreme heat events, sea level rise, storm surge, wind wave effects, ocean acidification, an increased coastal flood level event and a wave overtopping event. Climate data and trends were obtained from the literature and provincial documents, and current temperature data was sourced from Pacific Climate Impacts Consortium and Government of Canada Historical Weather Data. Ten climate change risk scenarios were assessed based on the likelihood and consequence of a climate hazard exceeding a predetermined threshold value and adversely affecting the sea dike. Of the ten scenarios assessed, three were found to be moderate risks related to ocean acidification, coastal flood level increase, and wave overtopping.