THE MISSISSIPPI RIVER

General facts: Third largest drainage basin in the World The Mississippi drains 1/3 of USA and a small part of Canada. Second longest river in the United States: 2,340 miles (3,770 km) The longest river, a Mississippi tributary, is the Missouri: 2,540 miles (4,090 km).

Location Source of the M River Mouth of M Gulfe of Mexico LA AR MS OK KS MO TN KY INIL IA WI MNND SD NE CO WY MT OH WV PA TX NM

Courses Mississippi upper courseMississippi lower course

Its main tributaries:

Discharge: Annual average rate: 7, ,000 m³/s. Mississippi has only 9% the flow of the Amazon River but is nearly twice that of the Columbia River and almost 6 times the volume of the Colorado River.

Importance and use of M Nation's most productive agricultural and industrial regions. Nation's chief navigable water route. Animals and plants including freshwater fishes, birds, deer, raccoons, otters, mink, and a variety of forest trees.

The BIG 6 The BIG National Wildlife Refuge System Improvement Act Hunting, fishing, wildlife observation and photography, and environmental education and interpretation as "priority public uses”

Threats to the Mississippi River Sediments The Louisiana coast is rapidly sinking into the Gulf, as the re-nourishing sediments no longer pass through the coastal marshes and wetlands. Some 16,000 acres of wetlands are lost there every year, totaling 80% of all wetland losses nationally. Pollution All municipal, industrial and agricultural runoff from the entire river basin is eventually deposited into the Gulf near the Louisiana Coast.: a massive dead zone off the Louisiana coast. 5,000 square miles each year since 1985 Habitat Alteration Landowners dependent on the Army Corps of Engineers for flood control, and destroying floodplain-associated habitats such as bottomland forests critical to many species of nesting and migrating birds.

Mississippi flood problems Frequency of flooding: almost annual Magnitude of flooding: major floods every 5 to 10 years; extreme flood: 40 years Causes of flooding: heavy rainfall in Appalachian Moutains Consequences of flooding: wide alluvial floodplain, death, habitat evacuation, livestock and crops lost, services destroyed. Case study: the great flood of 1993 (video)

Mississippi flood control Main policy: “hold by levees”. New schemes: dams and storage reservoirs, afforestation By cutting through meanders Large spillways The flow of the major tributaries had been controlled by a series of dams.

Effectiveness of flood control Levees alone are not sufficient: Great flood of An effective method: to construct coordinated groups of dams and reservoirs E.g: The Hoover Dam on the Colorado River, the reservoirs in the Miami Conservancy District, and dams of the Tennessee Valley Authority.

Presentation by Banteaymolu Alebachew Danamona Andrianarimanana.