Flooded urban street with parked cars partially submerged in water, heavy rain, and lush green trees lining the road

Using the curve: getting ahead of extreme weather in Canada

As climate change accelerates, Canada is experiencing an alarming increase in extreme rainfall events. According to the Intact Centre on Climate Adaptation, flooding is Canada's most expensive climate hazard, with heavy rainfall events becoming more frequent and intense due to climate change. Residential flooding risks from intense rainfall, river and coastal flooding is estimated at $2.9 billion per year. Last year, Toronto received nearly 10 centimeters of rainfall in just three hours. This type of surge is overwhelming outdated water management systems, leaving communities vulnerable to devastating floods and water-related disasters.  

The increasing financial burden of extreme weather along with the need for updated water management practices has underscored the urgent need for innovative strategies and tools to deal with it. Traditional methods of predicting rainfall and designing infrastructure are no longer sufficient in the face of changing climate dynamics.  

One promising development in this area is the introduction of a new national standard by CSA Group, supported by the Standards Council of Canada (SCC). The standard, known as CSA W231, Developing and interpreting intensity-duration-frequency (IDF) information under a changing climate, offers comprehensive guidance on creating and interpreting IDF curves. These curves are critical tools that use rainfall data and statistics to assess the likelihood of extreme rainfall events, providing a more accurate basis for infrastructure design and water management practices. 

The CSA W231 standard serves a wide range of professionals, including engineers, urban planners, policymakers, water resource managers, and researchers. By incorporating climate change considerations into IDF curve development, the standard aims to provide a robust framework for designing infrastructure that can withstand the impacts of extreme weather. 

As Canada continues to grapple with the effects of climate change, standards like CSA W231 are crucial for safeguarding communities and ensuring sustainable water management practices. The standard is available online via view-access at no fee for the life of the first edition in both French and English for Canadian electronic or IP addresses.