When the Levee Breaks

The problem with levees is they encourage development in vulnerable areas -- namely, the floodplain. Not only that, but when they fail, as they're prone to do, they raise the level of inland floods. And they're expensive. But despite the fact that floodplain management is cheaper than flood control, we keep fortifying levees and building in harm's way -- not just in New Orleans but in other flood-prone places like Sacramento, California and the bottomlands around Saint Louis, Missouri, where the Mississippi, Illinois and Missouri Rivers all converge. With the anniversary of Hurricane Katrina just around the corner, The Why Files asks why, after so many repeated disasters, we haven't yet learned our lesson.