The Mississippi River drains a major portion of the United States and Canada east of the Rocky Mountains. The lowest 123-kilometer section of the river from New Orleans (bright area in top, center of scene) to its “bird’s foot” delta in the Gulf of Mexico (bottom) can be viewed in this photograph. The light-brown, sediment-laden water of the river stands out against the darker bayou surrounding it here in southern Louisiana and the waters of the Gulf (bottom). Extensive management of the course of the Mississippi River has been performed by the U.S. Army Corps of Engineers since the 1960s. This is done to ensure that the waterway remains a viable shipping channel linking the Gulf to important upstream ports.
Management of dynamic, natural rivers systems such as the Mississippi have unintended consequences. Levees prevent flooding and ensure a navigable waterway, but they force the river to follow a single path to the sea. Dams prevent flooding, facilitate irrigation, and provide hydroelectric energy, but they also trap sediment that would otherwise get transported to the delta. The combined effects of these management practices result in a reduction of sediment supply to the Mississippi River delta, which is slowly sinking as a result.
January 1985, image STS-51C-143-27.