A little green can go a long way.
Researchers at the University of Maryland have found that even small patches of urban forest are effective for managing and infiltrating stormwater.
Assessing patches of urban forest in Baltimore, researchers found these areas — no matter how small — infiltrate stormwater at similar rates as rain gardens. Thus they, too, help curb pollution, runoff and nutrient damage to surrounding waterways that in turn feed into the Chesapeake Bay.
Conserving these unmanaged green spaces matters.
“There is a perception that urban soils are very heavily degraded and not as useful for some of these environmental purposes,” wrote Mitchell Pavao-Zuckerman, assistant professor of Environmental Science and Technology, Journal of Environmental Management.
“We found that 60 to 70 percent of the rainfall could actually be infiltrated on-site by these spaces.”
With assistance from Baltimore Green Space, the U.S. Forest Service and the geography department at the University of Maryland, Baltimore County, Pavao-Zuckerman and a graduate student studied not only how well these patches of forest filter stormwater but also explored how we think about green spaces in cities.
“There is always that tension when new development happens between leveling everything and going back to add in rain gardens and green infrastructure versus leaving what’s there and building around it. These results speak to the ability of these spaces, small and large, to act like a rain garden. From an urban planning perspective, it costs more money to put something in than to leave something behind.”
“We want to be thinking about green infrastructure not just as a basin or a rain garden or a patch of trees, but as an actual network of infrastructure,” Pavao-Zuckerman wrote. “How things connect in with the rest of that system is really important.”