Today, cities face substantial barriers to effective water management due to the sheer extent of non-permeable surfaces such as pavement and concrete. During rain events, the main function of these impervious surfaces is to concentrate and dispose of water as quickly as it arrives, sending it to storm sewers where it inevitably ends up in creeks, rivers, lakes, and oceans. Not only is this poor water management, but unfiltered water can cause major damage to ecosystems! Here in Calgary, it is not uncommon to see the consequences of poor water management in the form of major flooding events after large thunderstorms.
|Here is an example of a tree system that has been placed above the surface of the road which means it will never get access to run off and perpetually require city irrigation to keep it alive.|
This isn’t surprising, given that we have systematically removed close to 80% of our wetlands and paved a very large portion of the city. Thankfully, Calgary has started to re-install some wetlands around the river, but there is so much more that can be done!
The good news here is that this is an easy problem to fix. The really good news is that others around the world are already making progress and providing excellent examples for us to learn from and use in our own city.
On our recent trip to Australia, Michelle and I were amazed at how readily storm water harvesting features were integrated into the urban landscape.
During this trip we travelled to CERES (Centre for Education & Research in Environmental Strategies), a world class urban permaculture demonstration site right in the heart of Melbourne.
CERES is a thriving community that was built into an old quarry and is surrounded by the concrete jungle of the city. In order to showcase positive water management, they have installed a water-harvesting feature called a curb cut into one of the main entrances. A curb cut is literally a cut in the curb that allows water to flow laterally into a mulched basin, swale or other water infiltration device.
|Michelle is standing right in behind a curb cut. If the rain was falling right now she would be standing in a stream of storm water.|
In this case the water is diverted from the main entrance road and travels through a series of check dams, constructed wetlands and finally a pond.
|Look to the right to see a series of level check dams which receives the water from the curb cut above. The check dams lead to the pond on the left which is designed to clean the water for reuse.|
|Here is an up close shot of the check dams. Notice the grass growing on the level spots. This is where the infiltration occurs and water is stored.|
This system slows the water down and allows for de-silting and total infiltration into the soil. This seamless feature would likely go unnoticed by untrained eyes, but since we are permaculture geeks, we had no trouble spotting it! We observed the feature at length, trying to get the best photo for this blog.
Also during our trip to Australia, Nick and Kirsten from Milkwood Permaculture in Mudgee took us on an adventure to Sydney to celebrate National Permaculture Day. NPD gives permies all over the country a chance to share their projects with others, and allows for ideas and solutions to be exchanged by bringing people who care about permaculture together. It was great to see all of the budding and mature permaculture projects in Sydney, and we look forward to sharing some of them with you in a future blog!
While travelling through Sydney we had the good fortune of stumbling upon a discreet curb cut that fed into a constructed wet land. Nick and I were drawn to it immediately and decided that it had to be documented.
|Nick Ritar admiring the urban drool harvesting/cleaning device. Notice the concrete gabions by Nicks foot which allow the storm water into the infiltration and filter bed.|
The neat thing with these features is that they are integrated so well into the city landscape, and they also clean and slow down the storm water for the benefit of creeks, rivers, lakes and oceans.
|Another shot of the same curb cut.|
|The infiltration bed.|
With proper design, the water should exit the system dramatically cleaner than how it entered. Watch below as Nick describes how this feature works.
Another example comes from Tucson, Arizona where Brad Lancaster from www.harvestingrainwater.com is teaching people how to green desert cities by using low tech curb cuts to re-hydrate the verge also known as the nature strip, the space between the road and the sidewalk. I took Brad’s rainwater harvesting course in October of 2009 in Tennessee where he shared photos of his home before he started to harvest storm water in a serious way. It looked exactly like what you would expect a city that gets less than 305mm (12 in) of rain per year to look like - a desert.
|Brad's front yard in 1994 before he started passivly harvesting storm water. Photo courtesey of www.harvestingrainwater.com|
|The same shot in 2006 after the curb cuts, mulched basins and landscaping. Photo courtesey of www.harvestingrainwater.com|
Brad set out to show the world that green space is not limited to wet, temperate areas of the world and began cutting his curbs and creating mulched infiltration basins.
|Cutting the curb in Tuscon Arizona. It can be as easy as this. Photo courtesey of www.harvestingrainwater.com|
|Curb cuts along the gutter. As water flows down the stree durring a rain event some of the water will flow into the mulched basins behind the curb and infiltrate. Photo courtesey of www.harvestingrainwater.com|
These features passively harvest water from the roads during storm events and create benefits for the city as well as the ecology. These benefits include:
Within a few years, the desert landscape on his verge became an oasis of lush vegetation and a picturesque centrepiece of his community.
Brad travels around the world teaching others how to incorporate the same methods into their communities. It seems that many cities are beginning to follow suit. Portland, Oregon and Seattle, Washington have both introduced programs to build similar water harvesting features throughout their cities. Check out Brad’s website to see more examples of curb cuts and other innovative water harvesting features.
I know for a fact that Alberta could benefit tremendously from these ideas! For example, it always strikes me as quite daft when I drive down Memorial Drive and look at the newly planted tree median. The trees look beautiful, but why use drip irrigation to water the trees, when there is a huge, rather obvious rainwater catchment surface running directly beside them – I’m referring to Memorial Drive itself. Also, an amazing opportunity to filter the water collected on the road through wetlands and mulched basins is being missed. Such a system would ensure that the water entering the river is clean. Implementation of a simple water management feature, such as a curb cut, could solve this dilemma and others like it.
These types of opportunities are endless! I am just waiting for the chance to cut a curb and passively harvest water to make the city a better place!