Thirsty Street Trees: Slow Down Stormwater
When it comes to stormwater, it is time to slow things down. Much of our current stormwater infrastructure was designed to quickly divert water to underground sewer systems. But times have changed. Faced with increasingly unstable weather patterns that bring both frequent flooding as well intermittent droughts, today’s systems are taxed beyond capacity. Where to look for solutions? We suggest looking right under our noses, at a line in the landscape that is so familiar that it seems almost natural: the street curb.
Barriers Become Gateways
This line of travel where water flows at the edge of the street is demarcated by a designed edge that separates water from everything above the curb: trees, plantings, sidewalks, people. What if instead of a barrier, we viewed curbs as gateways. With intentional breaks in the curb, the curb can function to redirect water toward thirsty trees in stressed urban conditions. Consider the ability a tree single has to take up 13,000 gallons of water annually alongside the fact there are an estimated 6,000 miles of curbs in New York City alone. Curb design focused on trees rather than storm drains taps into trees as a natural powerhouse for water uptake, pollutant processing, microclimate cooling, and oxygenation!!
Soften the Urban Landscape
One change leads to another. With this one change in an existing system we initiate a shift toward a softer and more flexible streetscape, one that is more akin to the way natural systems work through connectivity and collaboration. The edge is no longer “hard” but permeable. It invites us to seek other opportunities to break through the continuous concrete surface and recognize the potential of working with the visible (above ground) from what is unseen (below ground).
This is much larger than the curb cut but it can start there. The subtle change gives way to perceptual change of the street and sidewalk as a living system, above and below ground. More green and less grey.
written by Lori Ball Horton