Monday, May 9, 2011

Floods along the Mississippi River lead to renewed calls for a change in strategy

Floods along the Mississippi River lead to renewed calls for a change
in strategy
By Brian Vastag and Frances Stead Sellers, Monday, May 9, 1:15 PM

The battle to tame the swollen Mississippi River intensified Monday as
the river crept higher in Memphis and the Army Corps of Engineers
opened a spillway in Louisiana to relieve stress on the levees
protecting New Orleans.

And last week, the Corps pulled a trick it had not been forced to use
in nearly 75 years: It blew open a two-mile run of a Missouri levee,
sacrificing about 130,000 acres of farmland and 100 homes to save the
town of Cairo, Ill.

The dramatic trade-off �reactivated the flood plain,� in engineer-
speak. It also highlighted limitations in the long-term strategy of
hemming in rivers with levees and dams, then pushing farms and towns
up against the river walls.

�For decades we�ve treated levees as the only line of defense� against
floods, said Andrew Fahlund, senior vice president of American Rivers,
which advocates for healthy waterways. �They ought to be the last line
of defense.�

In a move that echoes the approach taken by the Netherlands, which has
long wrestled with such problems, a nascent movement made up of
activists and city leaders victimized by flooding is pushing for
�natural river defenses.� They want to set the rivers free, if just a

Cities and counties are buying up homes and farms and relocating
residents to restore flood plains and wetlands. They�re moving levees
back from the water�s edge. And they�re ditching steep concrete
channels in favor of gently sloped green spaces.

Oft-flooded Napa, Calif., calls its $400 million project the �living
river.� Confronted in the 1970s with a Corps plan to turn the downtown
riverbank into a concrete channel, citizens said no. Instead, in 1998,
voters said yes to relocating 13 bridges, buying out some 100 homes
and businesses and restoring 900 acres of wetlands.

The project, now about two-thirds complete, according to Mayor Jill
Techel, dug the city�s Veterans Memorial Park into a bowl for holding
floodwaters. The wine-tasting destination�s downtown now features a
tiered trail that doubles as a spillway for the Napa River when it

Nonetheless, the town flooded again on New Year�s Eve 2005. Although
the project was incomplete, Techel said, the town drained in 24 hours
instead of the usual two to three days. The new wetland area �was a
sponge,� she said. �It took all that water.�

And in Pierce County, Wash., the Puyallup River � which has flooded 15
times over the past 20 years � will soon spread out a bit more.
Engineers have started pushing back levees, mile by mile. The
straightened, channelized river could no longer handle the increased
snowmelt from Mount Rainier, said county engineer Dennis Dixon. �After
100 years, we�re seeing that�s not quite working.�

Meanwhile, Cedar Rapids, Iowa, has been buying out 1,300 homes and 100
businesses in a flood plain inundated by the town�s �800-year flood�
of 2008, said Mayor Ron Corbett. �We�re really moving people out of
harm�s way,� he said, to establish a 220-acre �floodable greenway.�

But on May 3, the city�s voters narrowly rejected a one-cent increase
in the sales tax to pay for revamped, gently sloped levees. The Corps
also rejected part of the plan, leaving the city to search for other
funding. The project is now jeopardized, Corbett said.

Napa had better luck with the Corps, obtaining partial funding from an
organization that has long favored steep levees and straight, deep
main channels � geometry that drives floodwaters downriver fast and

Corps officials declined to comment.

Champions of natural river defenses say the Corps will have to adapt
its tactics as the world warms. Warmer air holds more water vapor,
which can trigger more intense deluges, said Kenneth Trenberth, a
senior scientist at the National Center for Atmospheric Research. A
report published in the journal Nature in February concluded that
North America experienced an excess of deluges in the second half of
the 20th century and fingered greenhouse gas-driven atmospheric
warming as a partial cause.
Levees �will be under a lot more pressure if climate scientists are
correct,� said Sandra Postel, a fellow at National Geographic and the
Post Carbon Institute. She thinks the record Mississippi floods this
year � on top of a �thousand-year� deluge in Tennessee last year and
widespread flooding in the Upper Midwest in 2008 � will prompt greater
adoption of natural flood defenses.

�Droge voeten�

The Dutch � often considered the world�s water management experts �
are further along with their policy of developing more natural defenses.

For centuries, the Dutch waged a stunningly successful war against
water, building levees and using windmills to pump the lowlands dry
and give their citizens �droge voeten,� or dry feet. Vast tracts of
land have been won back from the wet: More than 60 percent of the
population lives at or below sea level.

But the aggressive tactics came at a cost, said Dale Morris, senior
economist at the Royal Netherlands Embassy. The country has been
gradually sinking inside its giant defenses and is crossed by
increasingly tempestuous rivers rampaging seaward behind ever-bigger

The threat of devastating flooding in 1993 and 1995 � caused by wet
weather and snowmelt � and an ominous mix of demographic and climate
changes, including the promise of heavier winter rains, suggested
disaster lay ahead. It was only a matter of time before the rivers
burst their man-made banks and swamped the densely populated

Hence a 21st-century government vision for sustainable water
management, which involves lowering dikes in some areas and moving
them back, inviting the rivers to flood and creating space for them to
do so safely.

Called �ruimte voor de rivier� or �room for the river,� the strategy
is intended to help the rivers �cope with a lot more water than they
do now,� said spokeswoman Esther van Dijk. It involves about 35
projects � including relocating dikes, deepening riverbeds and even
permanently turning farmland back into flood plain � at a cost of more
than $3 billion. The effort is expected to be complete by 2015.
Households and neighborhoods, meanwhile, do their part by finding ways
to store stormwater temporarily, by using cisterns or flooding public
parking garages.

All involve trade-offs. Among the parcels of land identified to quell
the restless rivers, Morris said, is one along the Waal River in the
eastern part of the country. Once slated for development, he said, the
land has instead been turned into a park that can be inundated if
pressure on the riverbank rises.

The scale is different along the mighty Mississippi, but similar
�economic and human capital is at risk,� Morris said. The Dutch, who
have offered advice on integrated water management in several parts of
the United States, such as along the Sacramento River in California,
have not been asked to advise on this year�s flooding on the Upper
Mississippi, he said. �Not all the Dutch practices are applicable� to
the U.S. river, he said, but �some of them clearly are.�

Most of all, Morris said, the Dutch strategy represents a
psychological shift. It amounts to an acknowledgment that if you want
to keep your head above water, you have to be prepared to get your
feet wet.


(Note: For a detailed analysis of the problems with engineered flood
control by International Rivers, see:

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