Predicting and alerting for coastal flooding

Publishing Date

In response to increasing coastal flooding risks, the Meteorological Service of Canada (MSC), a branch of Environment and Climate Change Canada (ECCC), recently launched a five-year initiative entitled the Predicting and Alerting for Coastal Flooding (PACF) project. To help advance this work, ECCC is seeking Geographic Information System (GIS) data from municipalities and regional districts that pertains to near-ocean infrastructure.

Coastal flooding occurs when low-lying, normally dry land (situated above the highest tide) is submerged by seawater from a combination of high astronomical tide, storm surge and wave action. It is a relatively common occurrence along the BC coast, especially from November to February during king tide events. Additional critical factors are wind direction, the amount of open water over which the wind travels and storm severity.

Memorable recent examples of severe damage from these events include January 2022 (Vancouver/English Bay, Qualicum Beach, West Vancouver), January 2020 (Nanoose Bay), December 2018 (destruction of White Rock Pier), February 2006 (Beach Grove, Tsawwassen) and numerous events on the east coast of Haida Gwaii from 2003-05. However, it is expected that the number of potential yearly events, the extent of vulnerable coastline and the resulting impact of coastal flooding will increase due to global sea-level rise in combination with the increased intensity of storms.

In response to this, the PACF project was launched. MSC is developing comprehensive coastal flooding prediction and alerting services, with the capacity for meteorologists to disseminate coastal water level alerts for Canada’s entire coastline. Additionally, to support the emergency management community, early notification products of coastal flooding risk are being developed that will articulate the probability and potential impact of coastal flooding out to five days.

The project will leverage ECCC’s high-performance computing resources as well as recent environmental modeling advancements for predicting astronomical tide, storm surge and waves that contribute to coastal flooding. It will also incorporate the growing risks due to climate change, especially where there are key information and service gaps, thereby supporting increased resiliency for coastal communities.

To accomplish these goals, ECCC is engaging stakeholders in many jurisdictions within BC to understand requirements, vulnerabilities and current service levels in order to better predict, prepare for, and respond to coastal flooding events. The data sought - GIS data that can determine tiered elevation flood stage thresholds for coastal infrastructure (buildings/roads/danger to life) – is challenging to acquire, as there is no central repository.

This is why the federal government is seeking help from BC coastal municipalities, regional districts and First Nations communities, particularly planning, public works and/or engineering departments. Stage-level data for infrastructure provided by municipalities and regional districts could play a pivotal role in helping ECCC deliver appropriate coastal flooding alerts to protect life, infrastructure, and property. Alerts are sent when the forecast water level exceeds thresholds provided by coastal stakeholders. Collaboration preceding and during a potential event would occur between MSC’s Warning Preparedness Meteorologists and staff from BC’s Ministry of Emergency Management and Climate Readiness down to municipal/regional EMOs to discuss potential impacts as well as the evolving weather story.

ECCC will be in a position to start testing its products and services this winter and would like to refine appropriate coastal flooding alerts for communities and stakeholders over the next year, as both the coastal flooding alerts and early notifications are expected to be ready by spring 2024. For more information or to understand how your municipality or regional district can deliver data to support the project, please contact Matt Loney, MSC Senior Meteorologist.