Higher temps mean heavier rainfalls and more flooding for Vermont; do we head for the hills?

A scene from Route 11 between Chester and Springfield. Photo by Peter Miller

Olive Branch, Ill., has decided to move.

Yes, that’s a town, population roughly 800. The whole town will relocate, according to professor Nicholas Pinter at Southern Illinois University in Carbondale, who is advising town officials in the effort. Last May, the town, which sits on low-lying land along the Mississippi River, was under water for days.

It wasn’t the first time, and not likely to be the last. Starting over again in the same place seemed impractical, not to mention very expensive. So Olive Branch is heading upland.  With the help of the Federal Emergency Management Administration (FEMA), the existing buildings will be demolished and replaced on higher ground. Olive Branch is getting out of the flood plain.

An idea that might interest – if not exactly appeal to – many a Vermonter about now, especially those whose towns had been flooded once or twice before Tropical Storm Irene inundated them again last month.

Floods, to be sure, are less common in Vermont than in the Mississippi Valley. The last big one was 84 years ago.  Having to muck out once a century or so would not seem to justify violating what professor Pinter called the “emotional attachment to the current site” of a town or village, not to mention the expense and inconvenience of relocation.

Besides, this isn’t the Midwest, where one can go upland and still be on level terrain. Nor is it the Rockies, where rivers flow past mountains, but mostly through public land where no one lives, farms or drives. More than most states, Vermont is settled in towns and on farms with a river on one side and steep slopes not far away on the other.

Moving a town halfway up a mountain would seem both impractical and disagreeable.

But suppose that in the future flooding is more a once-a-decade than a once-a-century event. Even without another storm with Irene’s power and range, a rainier climate could bring repeated floods to several Vermont towns.

How many muckings-out is too many, both for the residents and for FEMA’s budget?

The question is appropriate because a rainier climate is just what many predict for the next few decades, if not beyond. Among the predictors is Gov. Peter Shumlin, who blamed the storm on global warming.

“We understand that the flooding and the extraordinary weather patterns that we’re seeing are a result of our burning of fossil fuels,” Shumlin said in a radio interview just before the storm hit. “We didn’t used to get weather patterns like this in Vermont. We didn’t get tropical storms.”

The governor is a bit ahead of the science here. The proposition that recent extreme weather results from global warming has not been conclusively demonstrated.

On the other hand, it hasn’t been conclusively refuted, either. If anything, dismissing the connection seems more irresponsible than accepting it. In regions with moderate or heavy rainfall (and that includes the Northeastern U.S., but not, say, Texas), warmer usually does mean wetter. If the temperature is going to be higher from now on – and that has been conclusively demonstrated, well-funded attempts at denial notwithstanding – more rain is likely to fall, perhaps enough to create more floods.

We’ve been collecting data for at least eight years. We have a flood disaster in Vermont almost every year in some locale or other.”
- Michael Kline
ANR

Even without moving whole towns, this possibility – added to the damage done by Irene – could have a substantial impact on how Vermont plans, develops and regulates in the future. Probably not moving towns, but possibly support for stricter regulations on covering up flood plains with buildings, roads or even cropland.

Some of that might be controversial.

“It can be a significant change,” said Michael Kline, manager of the Agency of Natural Resources River Program. “The 1927 flood changed Vermont quite a bit, and the impact of this flood will probably be comparable.”

Not hidden or secret, but largely out of the public eye, conversations about Vermont’s rivers and flood plains have been going on for some time.

“We’ve been collecting data for at least eight years,” Kline said. “We have a flood disaster in Vermont almost every year in some locale or other.” For all the “misery and loss” of Irene, he said, the flooding could raise the profile of a “conversation that’s been going for years before this flood hit, to develop a whole new flood hazard program, dealing not only with inundation hazards but with erosion hazards. What’s the behavior of our rivers? How much flood plain is needed to dissipate the erosive energy of our rivers?”

Perhaps one reason these questions stay out of the spotlight is that they illustrate a reality Vermonters might want to avoid: rivers aren’t really “rivers” anymore; they are systems. They have been, in Kline’s words, “historically manipulated – confined, filled and straightened so development could grow up around them.”

Much of that development has been beneficial. Even an environmentalist such as Kim Greenwood, the water program director for the Vermont Natural Resources Council, said there’s no reason to feel guilty about floodplain development. The rivers, she said, were “historically the most convenient place to be.” The land was more fertile, the terrain easier to build on, and besides, “everybody loves being near the river.”

The problem, she said, is that “the closer we get to them, the more damage we do to them.” Vermonters, she said, don’t have to find out-of-the-way places to see a good example of a ruined flood plain. They can take a two-minute walk from their state capitol building to see a narrowed, confined, Winooski River flowing past buildings and parking lots covering what once was its flood plain.

The river, she said, “has no access to the flood plain.”

In this sense, she said, Irene has presented Vermont with “a real opportunity, the opportunity to move one building from one side of a parking lot to another,” allowing the river to reclaim a patch of its flood plain.”

And even just a patch can be useful, she said, “to really help with flooding impact.”

Kline agreed. One impact of all the development along riversides, he said, including some projects meant to control floods, is that in the long run they “make some of these floods a lot more powerful.” But, he said, it isn’t necessary “to give rivers complete use of the valley. If we can provide enough access we can dissipate quite a bit of that energy.”

There is a science behind this.  It’s called fluvial geomorphology, defined as “the study of landforms shaped by water.” It assumes that by studying rivers – their size, shape, flow, gradient, riverbed material and more – scientists can determine how much flood plain the rivers need and how much can be safely developed. It is not without controversy, but its basic premises have been accepted by the American Society of Civil Engineers, the federal government’s natural resource agencies and several states, including Vermont. It underlay the passage last year of Act 110, declaring that “it is in the public interest to establish policies, plans, and rules that encourage and promote protected river corridors and buffers.”

Thanks to Irene, Vermonters are likely to hear more about this law, the work already done because of it, and its possible future consequences, which could be significant even if no town decides to move uphill.