Solutions for adapting to heat and heavy rain

“Heat islands” are urban areas where the ambient temperature is higher than in surrounding areas. These spaces are generally highly mineralized, i.e. paved with asphalt or concrete. Demineralizing our living environments by replacing asphalt and concrete with plants and green infrastructure is an excellent way to reduce the impact of heat.

Vegetation and green infrastructure (retention basins, vegetated walls and bioswales, etc.) help to create “cool islands”, i.e., areas where people can cool off. For example, mature trees in the city create shade, and climbing plants protect walls from the sun’s rays and bad weather. In these vegetated cool islands, it can be up to 12 degrees cooler than elsewhere in the city. This can make a big difference to people’s health during heat waves.

Asphalt surfaces also prevent rainwater from being absorbed by the soil. Planting vegetation can help absorb precipitation, reduce rain runoff into sewers and prevent flooding in urban areas. This can prevent excess water from ending up in the basements of homes, for example.

As well as reducing the impact of heavy rain and heat, green infrastructure offers many other advantages. These developments help to create living environments that are conducive to physical and mental health (french only) by improving air quality, the water quality of certain watercourses (plants can act as natural water filters) and pedestrian safety (with a wider sidewalk and plants separating the street from the sidewalk, for example). Moreover, contact with nature helps reduce stress in humans.  

Green infrastructure also benefits the environment by helping to conserve ecosystems and preserve biodiversity. 

Several projects are helping to make Québec more resilient to heat and rain. Here are just a few examples.

Place des Fleurs-de-Macadam, on avenue du Mont-Royal, was formerly occupied by a gas station. It has now been transformed into a floodable public square with green infrastructure, street furniture and a suspended work of art. The site can receive up to 30 cm of water, which will be directed to the ground within 48 hours rather than down the drain. It can also be used to cool the population in very hot weather with its water jets.

Avenue Champagnat (french only) was redeveloped to include a bioswale (a shallow ditch with vegetation, often in a strip, which allows rainwater to infiltrate into the ground). This absorbs large quantities of rainwater, reducing the risk of flooding. The greening of the avenue and the widening of the sidewalks make it even safer and more pleasant for pedestrians.

The greening of rue Saint-Maurice (french only), in Trois-Rivières, reduced heat islands in the area and improved rainwater management over a 1.3-km surface area. Several rainwater drainage infrastructures were installed, and over 1,000 shrubs, 135 trees and 18,000 other plants were planted. All these installations contribute to improving the quality of the groundwater, as well as beautifying the neighbourhood.

The Sous les pavés (french only) project by Montréal’s Centre d’écologie urbaine aims to transform asphalted living environments into green, sustainable spaces with the participation of local communities. Since its launch, the project has removed over 3,000 m² of asphalt, thanks to the efforts of over 1,300 volunteers. Over 300, trees and almost 3,500 other plants have been planted. The project fosters civic engagement, helping to strengthen community solidarity in the face of the impacts of climate change.

To promote the well-being of its citizens, the Ville de Saint-Charles-Borromée is developing green spaces to counter the effects of heat islands on the population and facilitate stormwater management. The city’s infrastructure is also being redesigned to support active mobility.

The Gouvernement du Québec has released an interactive map of urban heat and cool islands (french only), in collaboration with the Institut national de santé publique du Québec and the Centre d’enseignement et de recherche en foresterie. 

The aim of this geomatic tool is to help locate urban heat and cool islands. It also aims to present a surface temperature gradient for each in order to target locations where priority action needs to be taken to reduce risks.