Green Spaces and Permeability
The role of green space in modern cities is multi-faceted. Its aesthetic value can attract tourism, increase urban biodiversity and serve as a gathering space for communities.
Green space also provides a crucial ecosystem service in the form of stormwater management. As cities transform into concrete jungles, their abilities to handle precipitation and runoff take a sharp downturn. When water can’t permeate the soil, it flows across the land, picking up pollutants and contributing to flooding.
The process of increasing the infiltration potential of cities through conserving natural areas, increasing the infiltration potential of surfaces and reducing runoff is generally referred to as Low Impact Development (LID), and cities are increasingly recognizing these benefits; improving watershed health, reducing flood risk, maintaining groundwater levels and reducing potable water consumption chief among them.
The City of Calgary has been implementing LID principles to reduce pollutant and sediment loads into the Bow River and mitigate flooding. They are doing this by using permeable pavers and porous asphalt, enhancing the infiltration capacity of green spaces with rain gardens and bioswales, and installing green roofs, which have the added benefit of mitigating urban heat island effects.
The City of Kitchener, a stormwater management leader in Canada, takes it a step further by offering residents financial incentives to keep stormwater on their properties using rainwater collection, rain gardens, grass swales, infiltration galleries, etc. Kitchener’s innovative stormwater credit program was the first of its kind in Canada, but is now being used as inspiration for other municipalities in Canada and worldwide.
Fortunately, increasing green space and infiltration is often less expensive than traditional stormwater management infrastructure, has very few downsides and the added benefit of making a cities appear more beautiful, clean and inviting.
So, what do you think? Are green cities attractive community centres or productive hubs of ecosystem services?