A Flood of Concern in Roanoke: After an Urban Ecosystem Analysis, Officials Agree Increasing Tree Cover Is the Best Way to Alleviate Long-Standing Problems
Brzozowski, Carol, American Forests
Roanoke, Virginia, sits at the head-waters of three major water systems: the New River on one side of the watershed flows into the Mississippi River, the Roanoke River flows to the Outer Banks, and the Upper James River flows to Chesapeake Bay. Over the years major flooding problems, caused by Roanoke's valley location together with urban development that has increased impervious surfaces, has prompted government officials, private agencies, and citizens to establish efforts that will address the flooding.
The solution centers on trees.
It's an age-old, natural answer to the problems that appear when human development disturbs nature's sense of balance. "The city's founding fathers initially didn't understand the conditions inherent with building at the bottom of a 'bowl,'" says Tom Cain, executive director of Project Impact, an initiative of FEMA (the Federal Emergency Management Agency).
"One of our approaches is to rethink that," he says. "The city is only about 125 years old. We are really trying to get to a large-scale cultural understanding that if we are going to live here permanently, how would we design a city to go about doing that?"
Roanoke has had 18 floods in 125 years--one every seven years--causing more than $200 million in damage. Cain's organization, whose hazard mitigation team has worked with AMERICAN FORESTS' urban forestry department, is implementing an environmental approach working from the traditional disaster-management point of view.
"We are trying to change the culture and the way it preserves our water quality," Cain says. "We either have floods or drought. The other potential for damage here is wildfire and each of those is water-quality related. By using a low-impact approach, which we are trying to teach foresters, farmers, builders, and developers, we are hoping to not just restore the hydrology of the watershed, but to also clean the water at the same time."
Because trees slow stormwater runoff, allowing water to soak into the ground rather than run off into streams or storm sewers, trees are an important natural tool for areas prone to flooding. In a rural area the runoff rate might be only 10 percent; in a more urban, downtown situation that percentage can easily soar to 55 or 60 percent or greater.
Dan Henry, Roanoke's urban forester, worked with AMERICAN FORESTS on an Urban Ecosystem Analysis, conducted in 1998, that showed tree cover slipping from 40 percent in 1973 to 35 percent in 1997. A second, more detailed analysis in 2002 used high-resolution imagery to evaluate the city's current 32 percent canopy. As part of that analysis AMERICAN FORESTS also created a digital "green data layer" for the city to use with its Geographic Information Systems (GIS) data. These data and tools will help city officials plan future development while keeping nature in mind by calculating the dollar value of the "ecosystem services"--stormwater control and air and water quality--its trees provide.
FROM ANALYSIS TO ACTION
After the presentation of the UEA, Roanoke's city council and planning commission formed a volunteer, citizen-based urban forestry task force. Its goal: to develop a basic urban forestry plan that addressed canopy loss. The group's comprehensive urban forestry plan was approved by the planning commission and adopted by the city council in April 2003.
That action made Roanoke the first community to adopt a tree canopy goal--40 percent citywide within 10 years--as a result of Urban Ecosystem Analysis findings. Another goal is to plant enough trees on public ground to reverse the current annual net loss.
The UEA's findings have prompted other changes as well: revisions in public policy, a new urban forester position, and support for greenways and low-impact development. …