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Trees act as both ‘worst storm problems, best storm solutions’

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Trees act as both ‘worst storm problems, best storm solutions’

In the wake of Hurricane Sandy, dismembered branches obstructed roads, shattered windows and pulled on power lines. While trees can become a liability during a storm, they also play a role in mitigating its impacts by controlling runoff and flooding, as well as reducing water pollution, according to a plant and soil science professor.

Sue Barton, an ornamental horticultural specialist at the university, said trees are not only one of our worst storm problems but one of our best storm solutions. She said trees, shrubs and other vegetation intercept water partly from the physical barrier they create and partly by absorbing it through their root systems.

While engineered solutions, such as storm drains, permeable pavement and sand levees also effectively manage storm damage, Barton said these solutions are costly and invasive. Trees work preemptively while engineered solutions focus on efficient rain collection, but floodwater can become dangerous once it is consolidated, she said.

“Trees can do it in a much less disruptive way, and they’re just more effective at it,” Barton said. “It’s kind of the way nature designed it. It just makes more sense.”

Floodwater travels through the tree’s roots, where it is filtered and transpired into the atmosphere, according to Barton. The more quickly the water is absorbed, the less time it has to travel and accrue sewage and other organic material that can later be dispensed into water systems, she said.

Barton said trees are especially critical in urban areas, where most surfaces are pervasive and do not absorb runoff. The capacities of underground storm water systems are often insufficient for even relatively minor storms, she said. Water then bypasses the treatment center and goes into streams, according to Barton.

Carmine Balascio, a bioresources engineering professor, said urbanization can result in flooding, stream channel erosion, and associated ecosystem damage. He said it strips away natural vegetation that is useful in intercepting rain and preventing water from reaching the ground immediately. Soil absorbs water before it can runoff, he said.

“In this region of the country, the pre-colonial state of the land would have been forest,” Balascio said. “Natural landscapes aren’t as vulnerable to the deleterious effects of severe rainfall and runoff events that would be experienced in urban areas.”

While there are many useful engineered stormwater control practices, like curbs, gutters and storm drains, those that incorporate “natural” features, like bio-infiltration basins, rain gardens and buffer strips are most effective at slowing and filtering runoff, he said. The filtering removes contaminants picked up by runoff from urbanized areas, he said, which improves water quality.

A recent study by the Stroud Water Research Center concluded the most effective method of cleaning storm water is planting a 30-meter forest beside a water catchment center, according to Barton. She said this allows the water to be absorbed by the trees before entering the stream and potentially contaminating it.

Junior wildlife conservation major Lily Newton said there is a need to plant large trees with full root systems in spacious areas, rather than in areas with confined root spaces, such as in between sidewalks.

“People are more interested in aesthetics than making them practical,” Newton said “Not all plants, especially decorative ones, are capable of withstanding a storm.”

Contrary to what most people assume, tree root systems are actually very shallow, usually occupying the top 12 inches of soil, Barton said. When space is restricted, roots are both shallow and narrow, making them easily uprooted, she said.

Junior Kathleen Grimes, president of Students for the Environment, said planting trees not only lessens the impact of storm damage, but it also reduces the levels of carbon dioxide in the air. She said if more people knew storm damage could be lessened by planting trees, they would grab a shovel and do their part.

“Today many surfaces are covered in impermeable pavement,” Grimes said. “I don’t think people realize that the earth cannot properly bounce back from storms as it used to.”


Written by vaphc

December 5, 2012 at 5:03 am

Posted in Uncategorized

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