Lessons learned: Fixing the 'fixes' following Irene
GUILFORD >> Since Tropical Storm Irene swept across the Northeast, leaving destruction in its wake, Vermont has done an admirable job of cleaning up the debris, rebuilding its bridges and roads and preparing for the next storm. But one unanticipated challenge in the aftermath of the storm is fixing the fixes made in the clean-up efforts.
Following Irene, there were "conflicts between the large number of volunteers and local road crews who wanted or needed to do work in rivers, and the Department of Environmental Conservation's river engineers, who supported the efforts of municipal governments and the Agency of Transportation as they restored major transportation arteries," wrote David K. Mears and Sarah McKearnan in "Rivers And Resilience: Lessons Learned From Tropical Storm Irene," published in the Vermont Journal Of Environmental Law. "Some of the work done in rivers without our Department's authorization, or done contrary to our instructions, increased the risk of future flood damage. In those cases, river channels were straightened, river beds were deepened, and river banks were raised above the floodplain in ways that were not necessary or appropriate."
Following Irene, according to the National Wildlife Federation, "In a rushed attempt to reduce flooding to surrounding areas, streambeds were excavated and their channels were widened and straightened ... (turning) rivers into pipelines that rush floodwaters downstream, rather than allowing water to be absorbed in floodplains. Rivers cannot be contained by walls or deeper channels."
In Guilford, the Windham Regional Commission will soon begin the process of restoring about 700 feet of the Green River that was channelized following Irene. The "flood attenuation project" will demolish a berm that was built and replant shrubs and trees along the river banks, said Marion Major, a planner with the commission.
The funding for the restoration comes from the Vermont Agency of Natural Resources, Department of Environmental Conservation, Ecosystem Restoration Program.
"A floodplain is a valuable place where sediment and water can be 'wasted,'" said Major, explaining that the science behind attenuation is pretty simple. "The energy of the river going downstream gets disbursed over a larger area."
But when heavy equipment was brought into the Green River, a four-foot berm was built, creating a pinch in the river.
"That channelization is causing erosion downstream because the berm is in the way of the floodplain," said Major.
The $32,000 project calls for the removal of the berm to allow the river to access its natural floodplain again and planting vegetation downstream to ameliorate the erosion. The result will be less sediment input into the river and, eventually, an increase in woody debris and shading to improve in-stream habitat and water quality.
The final element of the project will be to secure a conservation easement on the 6-acre floodplain.
"The protection of this field is important to the health of the river and security of the road," stated a press release that was issued Aug. 3. "With this floodplain available, the vulnerability to flood hazards downstream is lessened by giving the water space to spread out."
The work that is being done on the Green River is emblematic of the challenges that faced Vermont communities immediately after Irene and in the five years that have followed, and since then, the state has been taking steps to prepare for a similar storm. But preparations can only go so far when buildings and parking lots still line many of Vermont's waterways, including the Whetstone Brook, which overflowed its banks during Irene and caused considerable damage in downtown Brattleboro.
Kate McCarthy, the Sustainable Communities Program director for the Vermont Natural Resources Council, said Vermont's downtowns and villages remain vulnerable to flooding events.
"These are places we care about, but what do we do about them?" she asked. "We have to think beyond the boundaries of our towns and consider what areas are upstream where we can make changes to slow the water down."
One of the things that can be done to prevent flooding is to protect Vermont's forests from fragmentation and development.
"The best thing you can do for a fast moving natural channel is protect the forests that have spongy soils that can absorb the water, slow it down and let it sink into the ground," said McCarthy.
"Just as a sponge soaks up a spill, these habitats mitigated the impacts of Irene by absorbing immense amounts of water," stated the National Wildlife Federation in a blog posted on Aug. 6. "In addition to providing valuable flood protection, riparian areas naturally enhance water quality by filtering sediment and nutrients as well as maintaining cooler stream temperatures. They also serve as corridors for many of Vermont's wildlife species to move throughout our fragmented landscape."
Downstream from these natural "sponges," said McCarthy, it's important to follow best-management practices when developing land use regulations. "Ideally, we want to prevent new development in the floodplain that prevents the river from its natural movements and functions."
Even though downtown Brattleboro was overwhelmed by the flooding, some of the newer buildings, such as the New England Youth Theatre, benefited from land use and development regulations the town instituted prior to Irene. But, said McCarthy, that didn't help many of the older buildings, which sustained major damage.
"The Whetstone comes down out of Marlboro and by the time it reaches Brattleboro it is moving fast," said McCarthy.
And in towns such as Brattleboro, Bennington and Wilmington, the waterways are channelized and when the rivers overflow their banks, they flood into the streets, into buildings and over bridges.
"The Whetstone Brook has a history of severe, unpredictable, and disruptive flooding," notes the "Whetstone Brook Watershed Stream Geomorphic Assessment and River Corridor Plan," presented in May 2008, three years prior to Tropical Storm Irene. "The underlying geology, soils and topography, combined with considerable and increasing development in the river corridor and a history of intensive channel management have created numerous and frequent human/river conflicts that are costly to both individuals and to the town of Brattleboro."
One of the best things Vermonters can do to prevent widespread flooding again, wrote Mears and McKearnan, "is to resist tinkering with the equilibrium conditions that developed in the millennia before humans settled this region and simply give rivers the room they need to move."
Maintaining the state's forests and restoring floodplains are key to preventing future flooding, but sometimes, the optics of creating floodplains can be deceiving, said Joe Defelice, a documentary filmmaker who founded Riverbank Media in East Dorset, which created the film "After the Flood."
"Down in Bennington, there was quite extensive work being done on the Roaring Branch," he said. "There was a fear that they were creating a moonscape and wrecking a lot of the existing fisheries. But the concept they were working on was establishing long-term flood plains within the river corridor. It might have looked bad while they were working on it, but the future health of the river was dependent on it being able to spill over its banks."
Even though it's been five years since Irene stormed across Vermont, Mears and McKearnan noted that due to climate change, Vermont can expect more storm such as Irene in the future.
"Climate experts predict ... an increased frequency of extreme weather events. ... State agencies should begin to look ahead and determine steps to reduce impacts of flooding and erosion in the face of an increase in the number and severity of natural hazards due to climate change."
Bob Audette can be contacted at 802-254-2311, ext. 160.
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