A river is a system is a complex and always changing system. A river does much more than drain water from the uplands to the ocean. A river shapes the land, producing areas of different sedimentation. Along the river banks the river deposits coarse grain material,this happens as the water is slowed down as it comes out of the river channel during a flood. The crest of the river bank slows the water down just enough so that only the coarse grain sand can settle out. This process forms the natural levees. As the water flows down the back side if the the levee and reaches the toe of the levee the water is slowed even more and fine grained silt is settles out of the water. As the water travels beyond this area it reaches the swap. Here the water is very calm and the very fine material settles out of the water forming clay. This deposition of different material has had its effect upon the settling of river communities. When a community is developed it usually develops on the levee along the river. The levee is the highest point along the river, this is beneficial for the community because the water flows away from this area. In more modern times building on the river levee has proved beneficial in the fact that the river deposited the coarsest grain material on the levee. This coarse material provides for a more stable foundation for buildings as opposed to the highly compactable material found at the toe of the levee or in the swamp.

As a community develops it becomes dependent on the river. As the river changes with time the community must also change. This can be seen in the New Orleans area. Since the levee system was completed in the late twenties, all the water coming down the Mississippi must flow past New Orleans. This has put a strain on the flood control system of the city. To counter act this higher volume of water the Corps. of Engineers has constructed the Bonnet Carre spillway. During times of severe flooding the gates of the spillway can be opened directing some of the water away from New Orleans to Lake Pontchartrain and out to the Gulf of Mexico. This is damaging to the lake due to the increased sediments brought in by the river.

Most river control structures deal with the problem of too much water, this may not be the case in the future for New Orleans. In the section of the river known as Old River, 60 miles NW of Baton Rouge, the river, in an effort to achieve an equilibrium with the ocean is trying to change its course from the present day channel to the Atchafalaya river. This would be devastating to New Orleans because the river would not past the city. To prevent this from happening the Corps of Engineers has built a structure to make sure that the water flows down its present course. This structure known as the Old River Control Structure is costly to maintain and is only prolonging natures way.
 
 

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