How cities can use rain gardens to help prevent flooding

A rain garden in Calgary, Alberta. A rain garden, or bioretention cell, is a shallow sloped area filled with plants and soil. (Maureen Flynn-Burhoe), CC BY

The Canadian capital of Ottawa was bombarded with 167 millimetres of rain in five hours earlier this summer in what the city called a one-in-200-year event. Close to 5,800 basement-flooding reports followed, and the worst of it hit the city’s west end, including the Crystal Beach neighbourhood.

Climate change is expected to make rainfall heavier. Short, intense downpours overwhelm drainage systems. Our research focuses on how rain gardens can help prevent flooding, and where cities should put them.