Which stream(s) within the City of Vancouver would be most suitable to use as an experiment in daylighting urban streams?

     Background
     Hydrological Concerns
     Public Realm Concerns
     Summary
     Data Sources
     References / Acknowledgements

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    What is underneath the city? What - or who - was in your neighbourhood before it was urbanized? What types of inhabitants? What types of vegetation? I wonder if you can find any "clues" in your neighbourhood, as to what the climax species would have been? In other words, what would be growing there, had it not been "re-developed"?
    So many of our urban land areas are quite literally "stamped" overtop of the landscape - so much so that their design (and their accompanying technologies) have allowed us to continue labouring under the delusion that "nature" is somehow foreign to our lives, and that it has become irrelevant. By way of illustration, consider the bumper sticker "Without nature, you are nothing!" What kind of a society would need to be reminded of this seemingly obvious reality?

    This issue has caused much recent interest in initiatives aimed at "Greening the City". This phrase, however, (like all politicized catch-phrases) invites confusion, as it means different - perhaps conflicting - things to different people. One thing we forget is that the city was already "green" before we got here. So, when we speak of "Greening the City", then - what exactly do we mean?
    The traditional response to "greening" has been to use natural elements to invoke images of "green-ness", images which may actually be more ecologically damaging. We mow down wildflowers and plant botanical gardens, and then spray these with toxic chemicals. We clearcut forests and plant street trees imported from half a world away. We tear out blackberry bushes and plant ornamental fruit trees that don't bear fruit.
    The reasons for this seemingly ironic approach to urban ecology may range from human attitudes to legitimate engineering concerns, bit where does this leave our attempts to "Green the City"?

    One recent trend in urban ecology and urban planning has been the "daylighting" of urban streams. Generally, re-development has required that formerly free-flowing streams become channels flowing through underground pipes. For example, it took me by surprise to learn that the street I live on was actually built overtop of a creek, which - if still alive - would be trickling sheepishly through an underground pipe. I was shocked that even my neighbours - some of whom have been here since our neighbourhood was urbanized - did not know of this.

    Our urban design permits us to go on believing in the (perhaps reassuring) myth that cities (and the human world in general) exist independantly of ecosystems. This belief has led to numerous ecologically irresponsible beliefs that are only now being called into question.

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    Another issue highlighting the need for urban stream restoration is the trouble associated with runoff. Goudie (1993: "The Human Impact on the Natural Environment") and several others including Ann Riley, (author of "Restoring Streams in Cities", 1999) note the hydrological problems caused by conventional urbanization and its traditionally impermeable surfacing. Think of your neighbourhood. How much of the surfacing is impermeable (eg. concrete, asphalt, etc)? When it rains, how many materials are washed away into storm sewers? We map land use, but rarely do we map land cover, which, from a hydrological point of view, is far more important.

    When we were in elementary school, our teachers taught us about the "Water Cycle". Under natural circumstances, rain would fall on a wooded or vegetated area, and slowly seep into the ground. Flowing as groundwater (or, in extreme conditions, as overland flow), water would slowly spring up and contribute to streamflow over a long period of time. This moistens the soil, and ensures a relatively constant flow of streamwater over time, ensuring that plants and animals get the moisture they need, and helping to maintain a diverse, healthy ecosystem.
    Unfortunately, impermeable surfacing interrupts the water cycle at its most crucial point: the interface between rainfall and vegetation. It seems ironic that in Vancouver, a city known for its mild and rainy climate, we have built a city on the assumption that it does not rain - so much so that during our winter rainstorms, our storm sewers exceed capacity, causing raw sewage to spill over into the Strait of Georgia, yet in the summer dry spell, they sit empty!
    As in most cases, we are unsuccessfully trying to replicate a service that nature provides for free: the management of stormwater.
    And, as in most cases, nature does it better.

    Even in a rainforest city like Vancouver, conventional urban development generally views rainwater as a "nuisance" that must be removed from the site as quickly as possible, hence the construction of the storm drains and expensive piping infrastructure mentioned above. This means that rainwater is moved very quickly through the system and out to sea, leading to an increase in the "extremities" of the flood hydrograph (i.e. streams will either be overflowing, or almost completely dry) Not only does this destabilize local ecological systems, but (from a human perspective), but our current attitude toward drainage also causes serious property damage due to flood erosion, and also (as alluded to above) required expensive and often redundant infrastructure. Consider that during the summer dry spell, storm drains simply "sit there costing money", whereas during the winter storm season, they are operating over capacity!

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    The daylighting of urban streams would also provide opportunity for developing a linear park or a focal point in a neighbourhood. It would similarly provide a focus for neighbourhood interaction and community services. Perhaps the attendant linear park could be integrated with a walking path, or a bikeway of some sort (depending, of course, on the nature and width of the required riparian zone.)
    Daylighting might also provide space for stewardship groups (eg. stream keepers), through which school groups would be provided with a hands-on opportunity to learn about urban ecology and environmental issues in general.

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    Many other cities have experimented with bringing such "buried streams" back up to the surface, to accomplish several goals:

• the re-introduction of habitat (especially avian habitat),
• to deal with stormwater more effectively and cheaply,
• the improvement generally of the public realm and the provision of a neighbourhood focal point,
• to foster a greater understanding of urban ecology in general,
• to develop financial savings in engineering budgets and maintenance.

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    Data Requirements:

1. A DEM of Vancouver
2. A map of "Buried Streams of the GVRD", (Dept of Fisheries and Oceans)
3. Zoning information for the City of Vancouver
4. Land use data for the City of Vancouver
5. Various datasets on civic infrastructure
6. Rainfall data (or surrogate?)
7. Soils or geological data for the City of Vancouver
8. Socioeconomic (census tract) data
9. The data I collected for a previous GIS project (Geog. 354)

Adams, L. 1994 "Urban Wildlife Habitats: A Landsape Perspective"
    University of Minnesota Press - Minneapolis

Goudie, A. 1993 "The Human Impact on the Natural Environment"
    Blackwell - Oxford

Knighton, D. 1998 "Fluvial Forms and Processes: A new perspective"
    Arnold - London

Acknowledgements to:
    Department of Fisheries and Oceans, Pacific Division
    City of Vancouver
    Greater Vancouver Regional District

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