Burlington Flood Response – Procrastinate or Mitigate?
Many people in Burlington (COB) remember the 2014 flood. It was a precipitation event that dropped 192 mm of rain in 7 hours compared to Hurricane Hazel (October 1954) which dropped 211 mm in 12 hours. Over 3,000 homes reported flooding while many more likely remained silent for fear of reprisal from their insurance companies. Hurricane Hazel has been the benchmark 100-year storm event and has been a standard in stormwater guidelines and regulations for the past 70 years. Provincial and municipal regulations have not been updated to anticipate projections for climate change, an emerging situation and an existential threat to humanity.
The issue is that significant flooding, similar to the 100-year storm event, has now occurred twice in 10 years. In 2014, the cost to the city exceeded $90 million and just 10 years later the cost of the 2024 storm is still being tallied. As temperatures continue to rise with global warming, the intensity, duration and frequency of precipitation events will become more pronounced. How much financial loss can property owners withstand? What is the city doing to mitigate flooding, heat and wind risks?
We witness erosion control projects, bridge reconstruction and creek fortifications in the city but this only addresses 3% of flood risk known as riverine. What about the other 97% of urban flood risk caused by overdevelopment, antiquated infrastructure and land use decisions? All Ontarians who live in a developed area, regardless of proximity to a waterbody, may be at risk.
The Importance of Greenspace
The urban space in the COB is located under the brow of the Niagara Escarpment with 13 creeks providing drainage in the 12 km distance to Lake Ontario. Burlington has historically been recognized for its greenspace but with new developments within the existing urban boundary, smaller lot sizes, increasing lot coverage with hardened surfaces, reduced setbacks, less parkland and paved boulevards, our City is moving away from its greatest protection from flooding. Grading and drainage (that would be dirt!) are increasingly important mitigation measures for climate change yet new developments dig deeper with more substantial basements leaving few spaces in the city which also support new significant trees to replace the degraded tree canopy. It takes decades and generations to replace mature, parkland-style trees.
The details of some engineering reports prepared for the city in the ‘70’s and ‘80s for example, highlight that the Millcroft Golf Course property and Sherwood Park recreational properties also act as floodplains for the City. It seems brilliant that we have dual-purpose land use where trees can grow relative to the new strategy of smaller lots combined with stormwater ponds. Trees can also grow on private lots where adequate greenspace permits but are not sustainable in stormwater ponds due to maintenance requirements. It is interesting that the city has suggested raising sports fields to avoid flooding but have they adjusted the grading requirements between homes?
How has the City Reacted to Flooding?
The COB declared a Climate Emergency (2019) and unveiled several plans including the Climate Action Plan (2020), the Climate Resilient Burlington Plan (2022), the Urban Forest Management Plan (2022), a tree protection By-law and Stormwater Management Plans and an idling by-law to address the changing climate. A lot of plans but what is the progress? Trees are being cut and new drive-thrus are being built!
The previous City Council worked with the Intact Centre for Climate Adaptation after the 2014 storm event. Since that time, the Intact Centre has developed many strategies to protect homeowners from climate change impacts, including preserving greenspace to mitigate flooding and proposing new more resilient building codes. Intact has also contributed to two important policy documents, one for the federal government and the second for the Auditor General of Ontario. Both of these reports recommend improved and updated flood mapping. But rather than continuing to work with Intact, the City, at the same time and in isolation, commissioned its own flood mapping in the form of creek studies using antiquated one and two-dimensional limited mapping which by their own admission is not consistent with insurance company assessments. During this same period, Intact Centre was working with the Insurance companies, the federal government and the provincial government and using newly developed, complex three-dimensional mapping to not only understand riverine flooding (3%) but to consider urban sources (flash flooding) which accounts for 97% of all flooding in Ontario.