multi-use green infrastructure

A recent article outlines how Toronto is building a new flood risk management infrastructure project that will also act as green, open space. This “green infrastructure” is something I have spent a great deal of time working on. Instead of building so called “hard infrastructure” – e.g. levees, dams, dikes, etc. – we build “soft infrastructure” that uses natural processes to manage flood risk (notice that I say flood risk management instead of flood control). That is, we use land to allow water to temporarily claim during a flooding event. Since it is open land, there are no damages to account for. The land is built in such a way with ecosystems such as marshes and geomorphologies such as highly permeable land that the force of floods can be mitigated.


But a really important thing to note is that these “green infrastructures” also act as open, green space such as parks and areas for ecosystems to thrive. That is, they are multiuse. Things such as levees only have one use: holding back water. Maybe there is a running path on top, but that is not the norm. The infrastructure is only in use when it is flooding. The soft path of “green infrastructure” is in use almost all the time. It works during floods, it works when it is not flooding allow people to use it as a place of recreation. And ecosystem services such as cleaning pollution are occurring at all times.


Interestingly, this infrastructure is usually cheaper than the alternative, traditional type. With climate change threatening so many cities, resources including financial ones will be under incredible strain. We could build more defenses for less with “green infrastructure”.


This article also looks at how river restoration and renaturalization are a key component of this strategy. During the past century, agencies such as the Army Corps of Engineers channelized, straightened, and concretized many rivers to control them and thus control their flooding. These rivers lost their identity as natural rivers and were just ugly scars of concrete. And they often did not work causing unintended consequences. Now we are undoing what we did before and returning the river to a natural state but in such a way as to mitigate flooding. The LA River is the largest such project, but I worked on such a project in Denver.


This is something I worked on quite a bit when I was at the US Army Corps of Engineers, especially when I was working in Thailand and Denver. I also did research on how this “green infrastructure” can cause “eco-gentrification” (that’s another post for another time). So this is something I have a great deal of passion about.


That said, sometimes I wonder if the terming of “green infrastructure” is just marketing. What we are in essence is just building out more land and retreating from intensified land use. There’s nothing too special about that. We move away from flood prone areas and change land use. Then again, such marketing is important to getting people to move away from the traditional, “hard” infrastructure that they may feel more safe with.