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TechnoratiIowa Flooding May Have Been Worsened By Man
Radically altered landscapes unable to absorb deluge
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?"The river would eventually rise 6 feet higher than any flood on record. Farther downstream, in Cedar Rapids, the river would break the record by more than 11 feet.
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 re-engineered by humans. Plowed fields have replaced tall grass prairies. Fields have been meticulously drained with underground pipes. Streams and creeks have been straightened. Most of the wetlands are gone. Floodplains 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."
Officials are still trying to understand all the factors that contributed to Iowa's flooding, and not everyone has the same suspicions as Enshayan. For them, the cause was obvious: It rained buckets and buckets for days on end. They say the changes in land use were lesser factors in what was really just a case of meteorological bad luck.
But some Iowans who study the environment suspect that changes in the land, both recently and over the past century or so, have made Iowa's terrain not only highly profitable but highly vulnerable to flooding. They know it's a hard case to prove, but they hope to get Iowans thinking about how to reduce the chances of a repeat calamity.
"I sense that the flooding is not the result of a 500-year event," said Jerry DeWitt, director of the Leopold Center for Sustainable Agriculture at Iowa State University. "We're farming closer to creeks, farming closer to rivers. Without adequate buffer strips, the water moves rapidly from the field directly to the surface water."
Corn alone will cover more than a third of the state's land surface this year. The ethanol boom that began two years ago encouraged still more cultivation.
Between 2007 and 2008, farmers took 106,000 acres of Iowa land out of the Conservation Reserve Program, which pays farmers to keep farmland uncultivated, according to Lyle Asell, a special assistant for agriculture and environment with the state's Department of Natural Resources. That land, if left untouched, probably would have been covered with perennial grasses with deep roots that help absorb water.
The basic hydrology of Iowa has been changed since the coming of the plow. By early in the 20th century, farmers had installed drainage pipes under the surface to lower the water table and keep water from pooling in what otherwise could be valuable farmland. More of this drainage tiling has been added in recent years. The direct effect is that water moves quickly from the farmland to the streams and rivers.
"We've lost 90 percent of our wetlands," said Mary Skopec, who monitors water quality for the Department of Natural Resources.
Crop rotation may also play a subtle role in the flooding. Farmers who may have once grown a number of crops are now likely to stick to just corn and soybeans - annual plants that don't put down deep roots.
Another potential factor: sediment.
"We're actually seeing rivers filling up with sediment, so the capacity of the rivers has changed," Asell said. He said that in the 1980s and 1990s, Iowa led the nation in flood damages year after year.
© 2008 The San Francisco Chronicle
9 Comments so far
Show AllI lived in Decorah, Iowa (a town in Winneshiek County in the NE corner) for 5 years, so I'm familiar with Iowa. While Decorah didn't get hit nearly as hard as places further south in Iowa, this recent flood did enough damage to get the county declared a disaster area by the federal government, so you can probably imagine what it looked like.
While it is often tempting to reach after single-causes to explain disasters like this, we should recognize that the kinds of devastating floods we see today are usually multi-causal phenomena. Certainly human-induced climate change is a contributor, but so too are things like overdevelopment of historic floodplains and the construction of levees.
I lived very close to the levee in Decorah. My house was on the west side of town and my wife, daughter and I would often walk with our dog through the area of tall grass prairie that was being regrown on the land in between the two sides of the levee meant to contain the water of the Upper Iowa River. It is a pretty sizeable levee, although the recent flooding was bad enough that it caused the evacuation of the retirement home that sits near to the levee on the west side. And the water came close to reaching the top of the levee in places.
So I'm familiar with levees. Residents in Decorah though are quite divided on their value. Obviously they can help protect homes built in areas that would otherwise be considered floodplain, but they ultimately pass on problems downstream, forcing floodwaters to rise and gather force as they move downstream rather than spreading out (as a river wants to do).
The fact is--and this is a hard thing to face when you're talking about human settlement of such areas--levees are terribly unnatural and probably cause at least as many problems as they solve. For people living upstream as a flood gathers, they can be the only thing standing between them and catastrophic loss of their property. But ultimately the problem is just compounded as you go downstream.
In addition, the presence of levees offer people a kind of psychological security that (sadly) often encourages further development of floodplains. This happened in Decorah during the time I lived there. Like many midwest towns, Decorah had a Walmart. But the Walmart corporation, apparently not satisfied with either its location or its size, wanted to build a Super Walmart, which they eventually built in an area near to the river outside of town that had been zoned as flood plain. The city (eager for the money they believed the Super Walmart would bring) allowed them to fill in the area that sat in the floodplain and got it rezoned for commercial construction.
This sort of shortsighted development (development in floodplain, building of levees, further development of floodplain) forms a disatrous cycle in many places in the midwest and will, sadly, lead to further disasters.
We need to commit to ending such disastrous development while remaining compassionate for the human beings who are devastated when such events occur. Many of the people hit hardest by them have limited options and understandably strong ties to the places most affected by these events. They are often the inheritors of the misguided activity of their predecessors as well as occasionally being agents of such activity. So we need to offer assistance and compassion just as much as we need to draw attention to the often human engineered causes behind the occurence of these disasters.
dmia June 19th, 2008 8:52 pm
A voice of reason crying out in a wilderness of fanatics.
Bullshit. A flood is a flood. Somebody's going to get wet.
I'm guessing most of you don't even know where Iowa is, let alone have been here. Before you post entries here making yourselves out to be experts, better get some education.
The Mississippi River has been carrying soil to the Gulf of Mexico for as long as the Mississippi River has existed. Look at a map of Louisiana. That delta didn't appear overnight. Duh.
Iowa has the best topsoil in the world and always will. I've been to the some of the wasteland where YOU live, and you wouldn't know black topsoil if someone shoved it up your ass.
But gee, maybe you're right. Why don't we all live on bean sprouts, bottled water, and raw fish. Give me a break.
In 1993, the same year there was extensive flooding along the Missouri and Mississippi rivers, I went to a conference for wetland scientists in Minneapolis. At the conference was scientist who had calculated that the historic wetland systems along those rivers would have been sufficient to absorb just about all of the 1993 flood waters. Now, 15 years later we are in nearly the same situation. The flooding may be even worse, but in 15 years, few if any wetlands in those river systems have been restored. I don't know how long such lessons take to sink into general awareness, but apparently it's more than 15 years.
When my brother-in-law recently dug a new basement where an old farm house had stood there was at least five feet of solid black top soil, a sponge that covered nearly all of Iowa when my ancestors arrived in Central Iowa in 1843.
It is now all gone . . . down the Missouri and the Mississipi to the Gulf.
And this article does not even mention all the levys and dykes built to control rivers throughout the midwest. This constrains waterflow in an effort to save some areas at the expense of others. The net result is more flooding.
May have been worsened by man?
It HADS been worsened by man. Meat farming/factory farming practices have reduced the topsoil in the region by as much as 8-12 inches over the last 40 years or so. This was the warning cry of Jeremy Robinson in his mid 1980's book 'Diet For a New America'
We need to study and build according to natures guidelines. No longer can we just move the earth to make it easy for us, we need to understand and work within the system that has been working long before us.
Monoculture needs to be a part of the past.
How many small family farms could be on a corporate farm? Not only would they provide a life for multiple families but the earth would be cared for much better & the food would be better.
Mining their topsoil, in effect, to produce corn for ethanol and livestock fattening.