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NASA National Aeronautics and 
     Space Administration

Mississippi River

Mississippi River

Upper left: Lower Mississippi River System (61A-484-010)
Hasselblad camera with 50 mm lens; early November 1985

This is a wide angle, regional view of the lower Mississippi River system. New Orleans is near the center of the image. The Mississippi River flows generally south from tNew Orleans and empties into the Gulf of Mexico through the Mississippi Delta. The fan-shaped region east and west of the current delta is made up of old lobes of the Mississippi Delta from earlier shifts in its course.

The shifting of channels in the lower Mississippi River is a natural process. Over the past several thousand years, 7 major Mississippi delta complexes have grown and then been abandoned by the river. The muddy region northwest of the Mississippi Delta is the mouth of the Atchafalaya River, the major distributary of the lower Mississippi River system. The junction of the two rivers is just off of the photo, but can be identified on a map of Louisiana.

Structures built by the US Army Corps of Engineers keep only about 25-30% of the Mississippi River and sediment flowing through the Atchafalaya. The distance to the Gulf of Mexico from the junction of the Atchafalaya and the Mississippi River. Some scientists have estimated that if not for the levee system build by the Arm Corps of Engineers, the Mississippi River would have been completely diverted through the Atchafalaya system by the early 1980s.

Lower left: Lower Atchafalaya Delta in Sunlight (STS068-271-060)
Hasselblad camera with 250 mm lens; October 4, 1994

The sun reflects off of the water surfaces in the photograph of the lowerAtchafalaya River in the southern Louisiana. Morgan City, Louisiana is near the middle of the scene. The bright reflective water highlights the swampy nature of the region and the complicated patterns of the Atchafalaya distributaries, dredged navigation canals, and inland, irrigation canals. The intracoastal waterway traverses west-east (roughly parallel to the coast). Because of so much sediment is carried by the Atchafalaya, the coastline is rapidly building outward, and the drainage pattern just inland also changes in response to sediment accumulation. Two deltas are actively building from the mouth of the Atchafalaya (eastern delta) and the Wax Lake outlet, a dredged canal west of the Atchafalaya. The delta formation contrasts with much of the rest of the Louisiana Gulf Coast which is experiencing erosion and subsidence from the lack of sediment being carried to the coast.

Upper Right: Atchafalaya-Wax Lake Deltas (51B-53-0011)
Hasselblad camera with 250 mm lens; early April 1985

In 1985, the Atchafalaya delta was only beginning to be built above the water surface. Submarine delta formation began in the 1950s. The delta started building above the water surface after the 1973 spring flood (Wells, 1987, Society of Economic Paleontologists and Mineralogists, pp157-166). This photograph is centered on the Atchafalaya-Wax Lake deltas. The Intracoastal waterway cuts across the scene. The mud-colored water carries about 30% of Mississippi River's spring flood.

Lower Right: Atchafalaya and Wax Lake Inlets (STS073-726-047)
Hasselblad camera with 250 mm lens; late October 1995

The deltas forming at the mouth of the Atchafalaya and Wax Lake outlet grew rapidly from 1985 to 1995. The photograph, taken 10 years after 51B-53-0011, allows a direct comparison of the amount of land comprising the deltas. By rough estimates, the area of the delta itself grew from about 8 square km to more than 50 square km. There are changes inland as well-lakes, swamps and low basins have filled in. Aside from Morgan City and the cultivated lands bordering the Intracoastal waterway, much of the region remains undeveloped.

Possible Starting Points for Student Investigations:
• Compare the distance to the Gulf for the two rivers.
• Look at the shape and frequency of river meanders. What is the real distance to the Gulf?
• Explore the development of the Intracoastal waterway. When was it developed, how, from where to where, and why inland?
• Explore the location and development of New Orleans.
• Examine the efforts of the Army Corps of Engineers in the area.