She explains how the Army Corps of Engineers has constricted the flow of the Mississippi River, and this constriction has caused the recent flooding in Iowa. (Missing from the discussion is an acknowledgement that The River used to flood every year. And as a former Mississippian, I insist that The River be spelled with capital letters.) The flooding situation in the Mississippi Delta was once an annual event.
At the time, no one lived there. But every drop of water that hits the ground between Pennsylvania and Denver has to go somewhere, and we're trying to make it flow through this little amusement park flume ride of levees, channels, dykes, and detours.
Back when the river flooded every year, the leftover silt and sludge created some of the most fertile farmland in the world. (Check out Tennessee Williams' Cat on a Hot Tin Roof and Big Daddy's references to his plantation as "28,000 acres of the richest land this side of the Valley Nile".) The levee system makes these farms possible, for better or worse.
The best book I've ever read on this is "Rising Tide" by John Barry. Barry explains the huge amount of water that goes past New Orleans every day, and how we've tried to control it. His explanations of local, state, and national political battles are fascinating. His analysis of how the Mississippi River flood of 1927 changed our political map is the best I've ever read. Sales of the book went through the roof after Hurrican Katrina, since Barry was one of the expert Talking Heads featured on television.
Have you ever wondered why the Republican Party, the party of Lincoln and the abolitionist states, was abandoned by African-Americans? John Barry explains why.
Based on the law of averages, Barry predicts that one year we'll have a rapid spring thaw in the Denver/Upper Midwest, combined with heavy rain in the currently flooded Iowa/Missouri area. No one, not even Al Gore, can tell us which year it will be.
But you don't want to be in New Orleans when this happens.