We’ve had some
minor flooding lately in the Gallatin Valley in southwestern
Montana, the consequence of a good mountain snowpack and a two-day
heat wave, followed by a big rain. It reminded everyone of the way
things used to work.
Some local landowners, however, were
“shocked,” I read in the paper. “I’ve lived
here 12 years and I’ve never seen anything like this!”
one said.
I could almost hear the I-told-you-so in the
hydrologist’s quote later in the same story. “This was
no 100-year flood,” he said. “This wasn’t even a
20-year flood. If they think this was a big deal, they have a
surprise coming.”
Sure, that landowner has been in
the floodplain 12 years and everything has been hunky-dory. But in
that same 12 years, a lot of neighbors have moved in, built on the
floodplain and on other floodplains.
The subdivision
reviews echo each other. Map-wielding experts minimize
environmental dangers and tout design strategies. Hydrologists
routinely warn of flood potential and groundwater depletion.
Mostly, money talks. Construction and real estate have been huge
economic engines around here. The developments go in, people build
on the floodplain. Then, when the inevitable happens, they are
shocked.
“People have a really difficult time
managing for cycles that occur at a rate longer than a human
lifetime,” says Monica Turner, professor of Wildland Ecology
at the University of Wisconsin.
Turner specializes in
natural disturbances, which include phenomena like flooding and
wildfire. Much of her career has been spent analyzing a really big
natural disturbance — the 1988 fires in Yellowstone — where she
did her early fieldwork.
In the case of the ‘88
Yellowstone fires, people used the word “unprecedented”
in every other paragraph, though according to Turner the only thing
unprecedented was our experience with fires of that magnitude. Our
precedent, it turns out, covered fires that peak on roughly a
20-year cycle. Turner’s research suggests that in the
Northern Rockies there is a 150-year cycle at work that burns
millions of acres at a whack.
“Back in ‘88,
people were busy blaming excess fuels and a let-burn policy in the
park,” remembers Turner. “What we’ve found
suggests that it has nothing to do with that. It’s the
climate.”
Early snowmelt, combined with prolonged
drought, high temperatures, strong winds and late fall
precipitation, produce the conditions ripe for a wildfire of the
1988 variety. A whopper. And there is nothing unprecedented about
it. It’s just a longer pulse than we’re accustomed to
measuring.
The same thing happens with people who build
their homes on the bank of a river, or on a low-lying flood plain.
It looks fine at the moment, beautiful views, a river coursing
past. What could go wrong?
A river is no more static than
a lightning-strike wildfire. It migrates back and forth across the
valley, chewing away at the banks. From an aerial photograph, the
river “corridor,” as opposed to its current channel,
reveals bank erosion, major flooding, channel shifting — all
effects that are “when” propositions, not
“if.”
We might get lucky. One hundred years
could pass without much drama. Then again, somebody’s turn
could come next spring, and again the spring after that. It’s
a little bit like trusting your retirement savings to the luck of
the casino.
Tom Olliff, who was a “seasonal park
grunt” during the ‘88 fires, and who now occupies the
post of chief researcher at Yellowstone National Park, thinks
Turner is right about our limited ability to understand change at a
landscape level.
“I think it comes down to the
length of a career,” he said. “I’ve had a long
career at Yellowstone, 30 years or more. I feel like I’ve
learned a lot, about fire in particular, over those decades. Sure,
there are some things I’ll pass on in the way of knowledge,
but a lot of it will go away when I do, and the management wisdom
clock will start new.”
As for me, I paddle a lot of
these local streams. I look at these river-hugging developments
from water-level perspective. I find myself wishing for a little
natural reckoning. I won’t go so far as wishing a 100-year
gully-washer on anyone, but an occasional wake-up call for
floodplain residents, like the one that just pulsed through town,
seems entirely appropriate.
And you know what? Let them
be shocked. Maybe they’ll think further down the road on the
next go-round.
Alan Kesselheim is a contributor
to Writers on the Range, a service of High Country News
(hcn.org). He is the author of nine books in Bozeman,
Montana.
Republish our articles for free, online or in print, under a Creative Commons license.
