Restricting river’s flow has long-term consequences for property, roads

BRATTLEBORO — On the face of it, it sounds like a reasonable idea to build a concrete barrier along Whetstone Brook to protect the buildings of Melrose Terrace. It would be wonderful to preserve those apartments for future residents, if we could do so safely and economically.

However, the lessons of Tropical Storm Irene and the increasingly destructive hurricanes of recent seasons show the futility of trying to restrict stream flow with artificial barriers like walls, levees, and berms.

In the first place, there is a connection between what happens upstream and damaging changes that happen downstream due to attempts to control the flow of water.

When barriers are built to restrict flooding in one place, the stream or river is confined and flows faster, scouring and deepening the channel and eroding banks downstream.

Eventually these changes cause the bank to collapse during a high-water event, and then these barriers, and the structures they are meant to protect, are lost or damaged.

This process is graphically illustrated on one of the many Vermont websites dedicated to flood resilience: floodtraining.staging.vermont.gov/sites/floodtraining/files/documents/river-corridors-chart-1.pdf.

We now know that letting streams and rivers meander in their natural floodplains is the best way to minimize flood damage when big storms occur. This means limiting the kinds of structures that can be built in river corridors.

This critical issue is on the minds and agendas of conservation and planning commissions all over Vermont. If you'd like to learn more, come to the Green River Watershed Alliance's special event, “Resilient Roads and Watersheds,” on Wednesday, May 30 at Broad Brook Community Center, Guilford Center, from 6 to 8 p.m. Our road crews - first-line defenders - will share the stories and challenges of their work and discuss flooding problems facing our roads.

Mark Twain said it best: “[T]en thousand river commissions [...] cannot bar [a river's] path with an obstruction which it will not tear down, dance over, and laugh at.”