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Mississippi River delta


The Mississippi River Delta region is a 3-million-acre (12,000 km2) area of land that stretches from Vermillion Bay on the west, to the Chandeleur Islands in the Gulf of Mexico on the southeastern coast of Louisiana. It is part of the Louisiana coastal plain, one of the largest areas of coastal wetlands in the United States. The Mississippi River Delta is the 7th largest river delta on Earth (USGS) and is an important coastal region for the United States, containing more than 2.7 million acres of coastal wetlands (4,000 square miles (10,000 km2) and 37% of the estuarine marsh in the conterminous U.S. The coastal area is the nation’s largest drainage basin and drains about 41% of the contiguous United States into the Gulf of Mexico at an average rate of 470,000 cubic feet per second.

The Mississippi River Delta is not to be confused with the Mississippi Delta region, an alluvial plain located some 300 miles (480 km) northward in western Mississippi along the Mississippi River.

The modern Mississippi River Delta formed over the last approximately 7,000 years as the Mississippi River deposited sand, clay and silt along its banks and in adjacent basins. The Mississippi River Delta is a river-dominated delta system, influenced by the largest river in North America. The shape of the current birdfoot delta reflects the dominance the river exudes over the other hydrologic and geologic processes at play in the northern Gulf of Mexico. Prior to the extensive leveeing of the Mississippi River that began in the 1930s, the river avulsed its course in search of a shorter route to the Gulf of Mexico approximately every 1,000-1,500 years. The prehistoric and historic delta lobes of the Mississippi River Delta have influenced the formation of the Louisiana coastline and led to the creation of over 4 million acres of coastal wetlands.

As the river changed course, the natural flow of freshwater and sediment changed as well, resulting in periods of land building and land loss in different areas of the delta. This process by which the river changes course is known as avulsion, or delta switching, and forms the variety of landscapes that make up the Mississippi River Delta.


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