———————————-
“We’re seeing more floods and worse ones.”
“We, as emergency managers, have to start saying,
‘Look, we have to take a much broader view,
otherwise as our climate changes, this is going
to be a big deal.’”
Criss said more than 100 years of tinkering with
nature’s flow is creating unpredictable systems.
“We not only have more floods and higher flood
stages, but they occur at every time of the year
now,” he said.
“If we can keep the water in the upper watersheds
for just a couple of months between seasons, we
can dampen a lot of the change that is forecast
because of the climate,” he said, Š and any
depression — ponds, beaver dams — will aid that
process.
———————————————–
Emergency Management
Dec 1, 2008,
Floods May Worsen as the Climate Changes
http://www.govtech.com/em/articles/565970
By Jim McKay, Editor
It has become apparent as floods increase in
number and severity that terms like “100-year
flood” are outdated and so are the country’s
strategies for protecting citizens against major
events–save some forward-thinking communities.
Experts warn that reliance on decrepit levee
systems and continued buildup of floodplain
areas, combined with warmer temperatures and more
rain, will result in more death and damage from
flooding. They urge a more balanced approach to
flood management to mitigate this looming threat.
In spring 2008, floods killed more than 20 people
around the country, destroyed tens of thousands
of homes and inundated cropland, resulting in
rising commodity prices. Much of the damage
occurred in the Midwest where flooding was termed
“historic.” In Missouri during a 36-hour period,
four rivers crested at record levels March 17-19.
These “historic” floods are occurring more often
than calculations suggest they should.
In 1993, Midwest flooding caused more than $15
million of damage and killed 50 people. That
flood, called the Great Flood of 1993, was
estimated by the Army Corps of Engineers as
perhaps a 250-year flood.
In 2001, Bob Criss, professor of earth and
planetary sciences at Washington University in
St. Louis, wrote that the 1993 flood was, in
reality, a 30- or 50-year flood. “They said I was
Chicken Little,” Criss said. But he feels
vindicated by recent events. “We’re seeing more
floods and worse ones,” he said.
There’s been progress at mitigating these risks
in areas like Tulsa, Okla., and the Pacific
Northwest, where progressive strategies have
controlled flooding. But overall it’s been slow,
with a continuation of the same philosophies.
“We, as emergency managers, have to start saying,
‘Look, we have to take a much broader view,
otherwise as our climate changes, this is going
to be a big deal,’” said Bob Freitag, a former
emergency manager with FEMA [Federal Emergency
Management Agency] and currently professor of
urban design and planning at the University of
Washington. “We, as emergency managers, see
everything that goes wrong: all the mistakes that
were made on that stream–upstream in terms of
fencing it in, removing all storage, removing the
forest that provides detention. All those
failures–we see [them] at a point when it
comes downstream and destroys homes.”
Warming Trend
According to the National Climatic Data Center,
the Earth’s summer temperature rose above average
for the 30th straight year in 2008.
Some areas of the country are experiencing more
rainfall instead of snow, which means more severe
flooding in the spring. “The Governmental Panel
on Climate Change has said that in many cases,
we’re going to see less water in an area because
of climate change, but when it comes it’s going
to be the gullywasher,” said Gerry Galloway, a
civil engineer and former brigadier general who
was assigned by the White House to lead a
committee assessing the Great Flood of 1993.
In response, most areas are trying to funnel more
water through narrower channels, the age-old
strategy. In the Midwest, the Army Corps of
Engineers is deepening channels with wing dikes
and other structures to allow more water to pass
through.
“That’s what they think they’re going to do,”
Criss said. “You might be able to do that locally
with continued maintenance and dredging, but
thinking they’re going to change the bottom of
the river for any significant difference is
folly.”
The idea of creating narrower, deeper channels
has been the Midwest’s flood-control philosophy
for more than 100 years, but 19th-century maps
show the Mississippi River is no deeper now than
it was then, Criss said. “How do you dig a hole
in the bottom of a river? You don’t, and thinking
that we can is not very bright.”
Any dredging done on the bottom of a river, in
this case the Mississippi, is pointless because
it will just fill back up with mud without
continuous dredging, Criss said. That leaves the
water nowhere to go but up.
Criss said more than 100 years of tinkering with
nature’s flow is creating unpredictable systems.
“We not only have more floods and higher flood
stages, but they occur at every time of the year
now,” he said. “Basically we have a more chaotic
river than we had historically. It’s not the
controlled system we think we’re trying to make.
We delude ourselves with these concepts.”
Levees have been the main form of flood
protection for much of the country, but a recent
report suggested that the Army Corps of
Engineers, which oversees many of the levee
systems, lacks an inventory of thousands of
levees that may be unsafe. That report came amid
heightened concerns after the record floods in
spring 2008 and more extreme weather forecast
because of climate change.
Indiana residents boat down a street that flooded
as a result of remnants of Hurricane Ike in
September 2008.
For the most part, the levees have held up, but
there were breaches this spring in Missouri and
elsewhere. And everyone knows of Hurricane
Katrina, where 60 percent of damage resulted from
a failed floodwall. “When you’re dealing with a
levee, you’re dealing with a pile of dirt,”
Galloway said. “In some cases, it literally
started with a ‘wind row’ from a farmer’s grader,
then somebody else added something to it and you
have no idea what’s in it. Some levees have a
history of 150 to 200 years and it’s hard to tell
what’s down at the base.”
Behind those levees, communities developed and
are still developing despite the hazards.
Galloway led a blue ribbon study in 1994 that
concluded with the Galloway Report on the 1993
floods. “That same report could be put out today
on the Midwest floods that we just had, and it
started with, ‘Don’t let people build in the
floodplain when they don’t need to,’” Galloway
said.
Yet development in dangerous areas continues
nationwide. Galloway pointed to parts of St.
Louis near the St. Louis River where development
continues despite the flood threat. “Why? It’s
close to downtown. There is lots of land in
Missouri on higher ground, but it’s cheaper to
develop; it’s closer in and people can say, ‘Oh,
I’m by the river,’ so they let them do it.”
These communities spring up behind aging levees
that offer protection from a 100-year flood. “One
hundred years means a one-in-four chance in the
life of a 30-year mortgage that the levee is
going to be topped and that there’s going to be
some sort of disaster,” Galloway said.
The term “100-year-flood” is misleading and not
applicable anymore, experts say. “I think we’re
really overstating; I don’t think those terms are
useful,” Criss said. “We need to acknowledge that
the language is flawed and there are better
approaches.”
Galloway said the 1994 report called for 500-year
protection, but no one has been willing to buy
into it. “The Corps of Engineers said by 2011
they’re going to have 100-year flood protection,”
he said of the rebuilding effort in New Orleans.
“Aren’t they lucky? They’re still in huge danger.”
Big Risk
Besides New Orleans, California probably faces
the biggest risk of a catastrophic flood.
Developers there continue to build in floodplains
behind questionable levees. “It’s simply because
that’s where the money is and that’s where
developers go,” said Jeff Mount, geology
professor at the University of California, Davis
and director of the Center for Watershed
Sciences. “It’s more subsidized bad choices.”
California is searching for ways to strengthen
deteriorating levees that protect populous areas.
In the Natomas community in Sacramento County, a
levee breach could put more than 11,000 homes 20
feet underwater. The state recently passed a $4.1
billion bond measure to shore up weak and eroded
levees.
But that’s not enough, Mount said. The 2006 bond
measure amounted to patching an old tire, he
said, and the state’s efforts have progressed
little since then. “The tire’s bald, all worn out
and wobbly, and the rim is rusted,” Mount said.
“Right now we’ve brought the car into the shop
and we’re all standing around looking at the
tire.”
Mount said patching the levees is necessary.
“It’s an emergency.” But he said those repairs
are merely a Band-Aid. As in flood management
elsewhere in the United States, there are a
number of solutions, all of which comprise a
balanced approach that experts say is necessary.
Mount said truly fixing the levees might mean
relocating them or removing them altogether,
letting water spill over onto farmland to ease
pressure downstream. “As long as we’re primarily
agricultural, that’s a viable alternative to
creating fortress-like levees, which are so bloody
expensive and environmentally damaging.”
A proposed Auburn Dam along the American River
above Sacramento would help, but is expensive and
environmentally harmful. “On a purely economic
basis, it doesn’t work,” Mount said. “And where
are you going to mitigate the drowning of 37
miles of river to the [Sierra Nevada]?”
During the Missouri floods this spring, levees in
the upper watersheds failed, which ironically
saved the communities downstream from being
inundated. “The urban areas owe their livelihoods
and safety to the fact that their upstream
neighbors absorb the shocks of the very large
floods,” Mount said. “It’s the same as a levee
setback, in a sense. The levee breaks, takes the
top off the hydrograph and reduces the stage
downstream so the suffering of a few is the
salvation of thousands.”
It could be a lesson in flood management.
Instead of flushing water downstream as quickly
as possible, keep it in the upper watersheds
longer with detention areas, by setting back
levees or by flooding farmland. “It’s an
excellent idea, but it’s turned out to be damned
hard to do,” Mount said, principally because the
United States is a nation that puts private
property rights as highest values.
But the concept has worked in the Pacific Northwest and Tulsa, Okla.
Retaining Water
Parts of the Pacific Northwest are experiencing
more rain and less snow, which mean more runoff
in the spring and less water during the summer.
It’s essential to find ways to keep the water
where it falls for a longer period of time. That
was accomplished with retention ponds in Oregon,
where a stream called Buck Hollow–a tributary
of the Deschutes River–used to flow
intermittently. When it did flow, it was big,
brown and laden with silt.
Farmers along the stream built detention ponds,
which keeps the water longer in the upper levels
of Buck Hollow. The result is a consistent flow
of cooler, cleaner water for fish and more water
on the farmers’ fields.
Freitag said it’s important to understand that
flooding is natural, even beneficial. Prior to
the 1980s, Tulsa was continually hit with severe
floods. During a 15-year stretch, the federal
government declared Tulsa County a flood disaster
area nine times.
That’s history. Since 1986, the area hasn’t had a
major flood. “They’ve removed homes in the
floodplain, they’ve made large detention areas,”
Freitag said. “They’ve removed some of the tax
base at a cost, but they don’t have to have huge
repairs and now they have more attractive areas.”
It started with a citizen-driven movement that
eventually gained support from City Hall, said
Ann Patton, a founding partner of Tulsa’s Project
Impact, part of a short-lived federal initiative
aimed at creating disaster-resistant communities.
“We’ve moved well over a thousand buildings out
of the floodplains physically; we’ve done a lot
of visually appealing detention ponds to hold
water back and release it more slowly,” Patton
said. “We have a lot of trails and parks that are
in the floodplain and fewer buildings.”
Tulsa ramped up its maintenance drainage systems,
which had been neglected due to a lack of funds.
The city imposed a fee on utility bills to help
keep up with the maintenance. It was all part of
a balanced approach.
“One thing we learned was that in trying to
address some of the problems on a spot basis, we
actually made them worse,” Patton said. “We
realized that you have to look at floodwater
management on a comprehensive basis. You can
actually make your community better–not only
safer, but better by using the resource.”
A Humble Approach
Tulsa’s approach is to work with nature “with
some humility,” Patton said. And it’s an
appropriate concept, experts say. “Tulsa has a
terribly balanced approach,” Galloway said.
“They’re probably the poster child.”
Tulsa’s success story took decades and still
isn’t finished, Patton said. “When the wrong kind
of rain comes–and it could have been Hurricane
Ike–there will be more water over the land
than we want, but hopefully it won’t be as bad.
We haven’t fixed it; we’ve ameliorated it.”
And that’s the idea. “People have this idea of
flooding as bad,” Freitag said. “It’s just
change.” He and the others said communities must
learn to live with the flooding, and even benefit
from it.
“Floods are natural events,” Galloway said. “By
leveeing off so much of the floodplain, we’ve
prevented regeneration of the soils. And that’s
one of the major problems in coastal Louisiana.
We’ve destroyed much of the wetlands by taking
the sediment and dumping it in the Gulf of
Mexico.”
The sediment acts as nature’s sponge, helping
store the water and regenerate the soil, which
perpetuates the process. In the Northwest,
retaining water in the upper watersheds to
continue that natural process is becoming more of
a challenge. “What we’re going to have here in
the Northwest as we lose those snow storages, is
streams that are going to peak earlier and
summers that are drier and we’re going to have to
capture water everywhere.”
Freitag said the Northwest is blessed with
valleys filled with river sediment, which, along
with depressions like detention ponds, can help
keep water in the upper watersheds for a little
longer. “If we can keep the water in the upper
watersheds for just a couple of months between
seasons, we can dampen a lot of the change that
is forecast because of the climate,” he said. The
idea is to use the floodplain for storage as much
as possible, and any depression–ponds, beaver
dams–will aid that process.
It’s just one part of a balanced approach that’s
necessary to living with nature’s floods.
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