Charlie Hohn, a graduate student from the University of Vermont, is spending this summer investigating what happens to water that falls on the Four Mile Run watershed of Pittsburgh, including Schenley Park and much of Squirrel Hill and Oakland. He shares some of his research with us below.
Do you ever wonder what happens to water that falls on the city during storms? At first glance, it seems to just disappear down drainspouts and culverts. In truth, the fate of rainfall and snowmelt that occurs in Pittsburgh has effects that reach beyond our backyards and drains.
As it turns out, when water rushes down the drain during storms it can overwhelm the aging sewage system of the city, and cause raw sewage to spill into the city's rivers. There are, however, a variety of things local residents can do to slow down this water and keep it out of the sewer. Larger scale actions in Schenley Park are also very helpful in meeting this goal.
One of the things I love about runoff and hydrology is that EVERYWHERE on land is part of a watershed. When it rains, or when snow melts, water anywhere on Earth has a path it will follow, either to the ocean, or sometimes to a salt lake or salt flat. Water that falls on Pittsburgh and isn't used or evaporated ends up in the Gulf of Mexico! That is about 1000 miles by road but significantly further along the twisty Ohio and Mississippi rivers. And every bit of that huge river (except rain that happens to fall in the river itself) comes from little tiny tributaries somewhere upstream (including those that travel underground in the form of groundwater).
On June 9th, I ventured into Schenley Park during a steady summer rain, to see evidence of water moving through the park. A significant portion of this water ended up in my hair and inside my raincoat, but it was a warm day so this was not too much of a problem.
Water was also pouring off bridges...
leaking out of overwhelmed storm drains...
passing through a rain garden where some hopefully soaks in and is filtered and released during a drier time into the creek...
... pausing in Panther Hollow Lake before it makes its way underground, through the sewer system, into the river.
In nature, things slow down water on its path to the ocean, and this water is used by the ecosystem, rather than just washing away. Plant roots, leaf litter, permeable soil, beavers, wetlands, and numerous ecosystem components "slow down" water before it runs off. In the city, where many of these factors are absent or reduced in scope, water just rushes away, causing floods and not sticking around during droughts. There are, however, many ways to slow down water and keep it around in the city for longer, and reduce flooding. For more information on ways to slow down water in your neighborhood or in Schenley Park, visit my blog at slowwatermovement.blogspot.com.