Rain gardens could cut Ottawa flooding by up to 50 percent, Carleton study shows
Researchers modelled how nature-based solutions like rain gardens could significantly reduce flooding impacts in Ottawa neighbourhoods affected by storms like the July 1 deluge.
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As the city looks for ways to manage flooding after the July 1 storm, researchers at Carleton University are pushing for nature-based solutions alongside infrastructure upgrades. A study published in July found that rain gardens — specially designed to collect and absorb stormwater into the ground — could dramatically reduce flooding impacts.
Jennifer Drake, Canada Research Chair in stormwater and low-impact development, and her team modelled rain gardens in the Crystal Beach and Byron and Golden neighbourhoods. They simulated how these gardens would perform during the August 2023 storm and a hypothetical 100-year storm.
Simulations showed rain gardens reduced flooding areas by as much as 50 per cent. The gardens work by holding water longer before it enters sewers, preventing those systems from being overwhelmed during heavy rainfall. They also reduced the total volume of runoff, the flow rates of water, and the amount of land inundated.
The researchers tested three scenarios: rain gardens on private property only, on city-owned right-of-way land only, and on both. "We have to use every tool in our toolbox to just even maintain the risks," Drake said, noting that climate change means more intense rainfall and extreme storms.
PhD candidate Ali Zoghi, who worked on the flood modelling as part of his thesis, noted that effective flood resilience doesn't necessarily require billion-dollar projects. Green infrastructure offers a cost-effective complement to traditional sewer upgrades.
The facts
How much could rain gardens reduce flooding in Ottawa?
Rain gardens could reduce flooding areas by as much as 50 per cent in Ottawa neighbourhoods, according to a Carleton University study published in July.
Which Ottawa neighbourhoods did researchers study for rain gardens?
Carleton University researchers modelled rain gardens in the Crystal Beach and Byron and Golden neighbourhoods.
How do rain gardens prevent flooding?
Rain gardens are specially designed to collect and absorb stormwater into the ground, holding water longer before it enters sewers and preventing those systems from being overwhelmed during heavy rainfall.
