are condemned to 20/20 hindsight.
From the WaPo today:
As the Cedar River rose higher and higher, and as he stacked sandbags along the levee protecting downtown Cedar Falls, Kamyar Enshayan, a college professor and City Council member, kept asking himself the same question: “What is going on?”
…
Enshayan, director of an environmental center at the University of Northern Iowa, suspects that this natural disaster wasn’t really all that natural. He points out that the heavy rains fell on a landscape radically reengineered by humans. Plowed fields have replaced tallgrass prairies. Fields have been meticulously drained with underground pipes. Streams and creeks have been straightened. Most of the wetlands are gone. Flood plains have been filled and developed.“We’ve done numerous things to the landscape that took away these water-absorbing functions,” he said. “Agriculture must respect the limits of nature.”
From FOCUS, March 22, 1994 (after the last “500 year flood” in 1993):
As Europeans settled – and cleared – the Mississippi River basin, it is unfortunate that they did not follow the example set by the Indians. Indeed, each time the Mississippi River flowed out of its banks onto its flood plain, the lesson had to be relearned: the Mississippi’s use of its flood plain would not be denied.
Nor would the flood-plain settlers or the upland farmers learn the principle of watershed unity that actions upstream could have an impact on areas far downstream. Thus in the uplands, forests were cut, prairies plowed and wetlands drained as tens of thousands of westward moving settlers converted the land to agricultural production.
Unknowingly, they began the process which ultimately led to the Great Flood of 1993 as well as earlier floods: as the land was cleared, precipitation ran off the land into the rivers faster and in greater quantity than before – the natural vegetation was no longer there to slow and retard runoff. Thus there were not only more frequent floods but floods of greater magnitude.
And we still haven’t learned.
This current flood, and the 1993 deluge, and the federal flood of New Orleans following Katrina all have the same source: the U.S. Army Corps of Engineers’ maniacal fight to control the Mississippi River as if it were a man-made canal.
It started out innocently enough: drain farmland (capitalism!) and save lives. But, it was not without hubris: We’re Americans, and Nature must bow to our greatness!
So, the projects grew. And the greater the commercial benefits of the Mississippi and its tributaries, the bigger the Corps budget became. The cycle became self-perpetuating: levees, dikes, and channels and locks are built to drain farmland and create a riverborne highway to carry all that grain – and the diesel, gas, fertilizer, chemicals, and anything else you can put on a barge or into a shipping container. And when the river floods because you’ve removed the river’s (and land’s) capacity to absorb cyclical high precipitation events, your budget gets even bigger because you’re also the agency responsible for FLOOD CONTROL.
The irony – and shortsightedness, and plain insanity* – of our dealings with the Mississippi and its environment are overwhelming:
As we drain the farmland, and channelize the Mississippi and its tributaries, we deny that farmland the alluvial replenishment it needs, requiring more and more chemicals to produce the crops for which the farmland was drained in the first place.
And, without those alluvial deposits and the water they hold, the farmland along the Mississippi and its tributaries begins to subside, making it even more vulnerable to flooding.
The fortification of the Mississippi’s banks, and the engineering structures that kept the River from changing course and maintaining an equilibrium with its banks and bottomlands, channeled and speeded up the River, making it less capable of absorbing extreme weather events like the unusually high rainfall totals of this May, June 1993, and the rain that fell north of New Orleans as Hurricane Katrina moved inland.
This fortification also steals necessary replenishing soil deposits from the Mississippi Delta, allowing storm surges and flooding further inland, and in turn allowing each storm that hits the area to carry more and more of the delta away;
And, as the delta is carried away, salt water from the Gulf creeps in, killing the freshwater wetland vegetation that holds what is left of the delta in place.
So what should we do?
We can start by looking at the Corps’ re-naturalization of the Kissimmee River in Florida. As they’re doing with the Kissimmee, the Corps needs to de-channelize the Mississippi as much as possible, and allow for seasonal flooding by buying out farmland and creating the riparian wetlands that have been drained over the past 150 years. Where possible, we should allow floodwaters to reach and replenish farmland. And to pay for it all: charge user fees to agribusiness, barge operators and others who benefit from commercial navigation and irrigation/flood control improvements on the river.
I’m not a geotech engineer – but the losses we’ve seen in life, property and infrastructure due to two “500-year” floods in 15 years are proof enough that the billions we’ve spent to harness and tame the Mississippi haven’t worked. We need to do something different.
We’ve tried engineering for more than 100 years. Why don’t we try backing off, and trusting mother nature, for a few?
*doing the same thing over and over again and expecting different results.
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