Copyright David Tenenbaum. The pinkish sand in the last pic was left by the flooding river. Some deposits were six feet deep, enough to destroy farmland. Courtesy NASA . In the United States, as in many other countries, floodplains have been a focus of development.
Channels allow ships and barges to haul bulk commodities like oil and grain.
Throughout the 20th century, the Corps built and maintained an extensive system of locks, dams and levees on the Mississippi and Missouri Rivers, which drain most of the United States, east of the Rockies. To farmers, barge companies and real estate interests, levees are critical for taming the rivers. But to environmentalists, they are artificial restraints that promote reckless development and farming in the floodplain. Certainly, some major rivers have been sundered from their floodplains. The natural role of a floodplain is to carry excess water during periods of heavy runoff, but when the floodplain is walled off behind levees, the artificially narrow river must rise higher to compensate.