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OtherEnvironmental Health - Part 3: Urban Growth By Karen Munro, M. Sc., Environmental Scientist
Ah, life in the city. We love it, and we love to get away from it all, too. Urban growth appears to be inevitable, especially among planners and developers.
Having seen the impacts of sprawling cities, decay of the inner city and suburbs that now overlap, recognizing that we have lost and continue to lose significant amounts of valuable farmland and forest and realizing that we can hardly afford to drive our cars around all those places, many communities are starting to talk about alternative growth strategies.
There are many options and approaches, but they all include densification – putting more people into the same area. We can build up, build more multi-family complexes, plan “complete communities” so we can work close to where we live. The approaches are called many names, including smart growth, livable region strategy, sustainable development … There are a lot of benefits to such planning initiatives, and they really are necessary.
My main worry about these strategies is that they don’t get to the root of the problem and deal with how we live, locally and globally. I worry that we will set aside green space now but want to use it later. Assume we start out now and keep 50% of the land for conservation, agriculture and resource use. Within a couple of decades, as we get a little more crowded, we may decide we need some of that green land for housing so begin to shave just a bit more off (say another 50%, in the name of compromise and for affordable housing, of course) - we now have only 25% green space left. Then, a couple of decades later, we’re just getting a little too crowded again, so … you get the picture. For smart growth strategies to work, communities will need to commit to preserving the green spaces for a long, long time.
On to streams, though. What happens when communities grow, or when new developments happen in a watershed? The effects of urban growth on streams are well documented now, particularly in British Columbia and Washington, but applicable everywhere. Two key indicators are increased impervious area (paved areas like roads, patios and rooftops) and loss of streamside vegetation (discussed in Part 2 of this series). Along with increased population size comes increased incidents of storm drain abuse (Part 1) and wear and tear on the habitat (Part 2).
As the percentage of impervious area increases, the amount of rainfall that can get into and filter through the soil to naturally recharge the stream decreases. This leads to higher peak flows in the rainy season and lower low flows during the summer, changing the stream channel (bank erosion, altered substrate characteristics) and making it more difficult for salmon and other native species to survive. Effects on salmon populations are noticeable at 12% impervious area. Suburban areas easily have 50% impervious. New York City – close to 100% if you don’t think about Central Park or that tree that might still grow in Brooklyn.
What can we do to help? At home, we can adopt ways that step more kindly on the earth, for example, using water wise and natural gardening methods, disconnecting downspouts off your roof (this allows water to drain to the soil to be filtered before entering the creek rather than entering directly to the storm drain system), and consider using permeable surfaces (pavers, wood decks) instead of asphalt and concrete in our yard or business.
On a broader scale, we can examine our own priorities, listen critically to other opinions and participate in development of official community plans and neighbourhood plans. We can challenge our city and regional planners to strive for truly sustainable communities and to set aside valuable green spaces in ways that are not easily lost in future generations. Here in British Columbia, for example, there are periodic challenges to remove land from the Agricultural Land Reserve, especially near populous Vancouver, where the Fraser Valley land contains much of the usable farmland in the area.
Like many other issues, the ongoing conversation and involvement in contributing to our communities is essential. We cannot be sure of the outcome, but we know that if we don’t speak about what is important, we may lose it. The relationship to human health should be obvious.
Some starting places for resources:
http://earth.google.com/ (great aerial shots of everywhere, close-ups of your community)
www.smartgrowth.org/ (North American wide organization with local offices)
www.gdrc.org/uem/footprints (ecological footprint calculation)
www.envisiontools.com/ (planning tools and scenarios)
www.gvrd.ca (sustainability efforts, storm-water management planning, livable regions strategy for the Greater Vancouver Regional District)
www… your town (check out what your community offers)