Can We Turn Victoria into a 'Sponge City'?
Don’t worry I know what your first question is. What is a 'Sponge City'? A few days ago I was listening to the Urbanist (which is a great podcast that you really should be listening to as well) and they had on Kongjian Yu, a Chinese landscape architect who is credited with popularizing the idea of the sponge city. Now, I have a fairly good understanding of modern water management practices, but had never heard the specific term 'sponge city' before. This has led me down a deep rabbit hole over the last number of days and got me thinking about how it could and should apply to Victoria. So, a sponge city essentially is an urban planning model the focuses on greener infrastructure to manage the water that passes through our urban environment. While for the most part, sponge city design has been focused on dealing with places that face annual flooding and significant storms, the idea has significant merit within our Victoria context.
As we know, Victoria doesn’t really face flooding on a regular basis, with the large volume of rainwater during the winter months, it does have significant runoff. This runoff which mostly comes from our road system can contain significant pollutants including toxic metals, oil, pesticides and many other chemicals. Slowing the entry of this water into our streams and waterways is a good way of lessoning our impact on the surrounding environment. The sponge city idea proposes to do just that.
What Makes Up a Sponge City?
A sponge city has almost limitless amount of ways to control and slow down water, however, the main ones that are in use are: Holding spaces within urban parks and gardens; natural green spaces and creek renewals; permeable pavement; and nature strips. Within urban parks and gardens this would usually be created through the addition of ponds and rain gardens. These spaces can slow the movement of water and clean it before it continues on to the storm water system. Re-establishing the natural environment is another way to manage water. In Victoria perhaps the best example of this has been the work to restore Bowker Creek and areas around it. You can read my series on Bowker Creek here, here and here. Permeable pavement can also be an easy way to slow water down as it can be absorb into the soil below a pathway or road rather than being collected and funneled into roadway drains. Again, this slows the water’s entrance into the storm water system. A final implementation is within nature strips in the middle of our urban environment. In Victoria, we have seen this be put in place in the form of bioswales alongside roads. Two of the most prominent are surrounding the Atrium building downtown and Hillside Mall in Oaklands. While we do have a few examples in Victoria, we definitely need more.
Benefits of Being a Sponge City
Victoria may not necessarily be the target candidate for being a sponge city, it would still have several significant benefits. Implementing some of the infrastructure could help alleviate local flooding within neighbourhoods, particularly those that are lower lying than the areas around it.
In Oaklands, while still significantly higher than sea level there have been large floods near Haultain and Belmont in the past. Furthermore, keeping water closer to where it falls and out of the storm water system will allow it to be absorbed more locally which could reduce usage from our larger drinking water supply, especially during the dry summer months. Additionally, if water is gathered into ponds, they can provide a cooling effect that could also mitigate some of the impacts of urban heat islands. Even having trees be able to gather more water and grow faster will have a positive impact in protecting us during the summer.
As the water is absorbed into a sponge city system, it will have pollutants taken out of it by the plants and soil meaning that the water entering the drainage system will be cleaner. I imagine that adding all of this green infrastructure would also have a positive impact on the animals that call Victoria home. We have already seen the beginnings of this with the rejuvenation of the Bowker Creek spaces.
Victoria Examples and Ideas
As I have pointed out, we have already seen some elements of a sponge city implemented in the form of bioswales and creek restoration. There are other good examples that you can currently see. A walk around Dockside Green in Vic West will let you follow a long pond and creek that not only works to manage some of the project’s grey water, but also takes in rainwater and holds it before it goes into the storm water system. Another wonderful example is the rain garden at Fisherman’s Wharf Park in James Bay. The park includes a large deep rain catchment pond that can fill up with water from the park and surrounding roads. The pond is full of grasses that can absorb water and some of the pollutants before it continues on into the nearby harbour.
While these examples are great, they are still few and far between. So what could we be doing differently to add more elements of sponge city infrastructure to the city? I think there are really three things that we could easily start doing: mandating bioswales as part of downtown developments; adding new collection ponds and rain gardens and rejuvenation of historical natural drainage systems.
As we can see with the Atrium project at Blanshard and Yates Street, bioswales can easily fit into the urban fabric and still maintain significant pedestrian space, while also providing an area for trees and also a place for stormwater runoff. Unfortunately, outside of a few office examples where the proponent is given benefits for meeting green building standards, water catchment infrastructure is rarely built. There have been numerous new residential buildings added over the last few years in the surrounding Harris Green neighbourhood and they almost all have basic grass boulevard instead of bioswales. I understand the need for areas to have pets use, however these could easily be a smaller area rather than the entire boulevard space surrounding these buildings (I really don’t like these grassy boulevards in general as they take space that could easily be provided to pedestrians as well, but I have complained about that many times in the past). Mandating bioswales in boulevard spaces would be an easy thing for the City of Victoria to put in place and it would do a lot to help manage runoff in the downtown area.
While we can talk about the need for new public spaces in around downtown, there are currently many that already exist, there are even more in the surrounding neighbourhoods. Many of these parks are made up of extensive grassy areas that are generally not used for much even when the grass is dry enough to walk on it. The addition of collection ponds and rain gardens could create some points of interest in these parks while also allowing for some better drainage in these green spaces. One of the biggest benefits would be that if a park was better drained into a collection pond, the surrounding grass space would be drier allowing for more year round usage. A great example of where this would work is in Harris Green at Cook and Pandora. I have written about this neglected green space (that is bigger than many parks in the city) before. You can read an older article and some of my ideas on how to improve it here. As it stands currently, the lower part of this park gets very muddy and almost inaccessible in the winter months. A collection pond located at the bottom of the hill near Cook Street would be a great focal point for the neighbourhood and it would remove a significant amount of the water that currently just makes the grass uncrossable. It would also allow for some of the runoff from the surrounding roads to be collected and kept out of the storm water system. Making rain gardens and collection ponds a part of many of our current parks would be relatively easy to implement.
You get the idea :)
The southern part of the Capital Region used to be crisscrossed by several small creeks and streams. A few of them can still be seen in parts including Bowker Creek, Cecilia Creek and the Colquitz River; though all of them have been covered or changed significantly by our city over the last 150 years. There has been some significant restoration work done on some of these waterways. That said, lots more needs to be done and there are more waterways that you may not know still exist right below our feet. Probably the one that has gotten the most discussion lately is the Johnson Street Creek that used to run from the marsh at View and Vancouver to the foot of the Johnson Street Bridge. You can learn more about this creek here. Doing what we can to restore these creeks and the watersheds that they represent is perhaps the best way we can work to make Victoria into a true sponge city. These creeks when daylighted and restored provide a home for wildlife, plants and trees which all work with the soil to help absorb water runoff. The creeks can also provide natural areas that become destinations for citizens to enjoy. Some of the restored areas along the Bowker Creek are a great example of this.
Sponge cities may have arisen to deal with the harshest impacts of climate change, however the idea also has the potential to make all of our cities more livable as well. I would love to know what you think about the concept and what we could be doing in Victoria to bring it about. Let me know in the comments!