Credit Digital Vision/Getty Images
Many gone-green folks grow gardens on their inner-city roofs in order to decrease the effects of urban heat islands and to increase biodiversity. A rooftop garden has another added benefit that is often overlooked. It can decrease storm water runoff.
Storm water runoff isn't problematic in and of itself, but when that storm water flows into the gutters and streets, it picks up chemicals and other bits of filthy detritus and carries that pollution into our streams and watersheds.
A new study from the University of Maryland has shown that these rooftop gardens can reduce runoff by 30 to 75%. The plants filter the impurities out of the water and release clean water back into the water cycle via transpiration. This is the same science that makes rain gardens effective.
Olyssa Starry, the graduate student behind this study, believes that a city that implements a green-roof policy caan save 8 million gallons of water a year. But you don't have to wait for a policy to be enacted; you can start growing plants on your roof today. (Weather and landlord providing.) Learn about how to grow a rooftop garden on How Stuff Works.
Rooftop gardens also reduce the risks of inner-city flash floods which can lead to property and resource destruction.
Like this article? Catch lots more on water and ocean issues in Blue August
