Victoria Streeter, age 13, of Meridian, Miss., for her question.:
WHEN WAS THE FIRST LEVEE BUILT?
A levee is a wide wail built along the banks of rivers to keep them from flooding over the land. In the United States, the term is used especially to describe wails or dikes built along the southern part of the mammoth Mississippi River.
The first Mississippi River levee was only three feet high. It was built at New Orleans in 1718 to keep the river from flooding a strip of fertile land.
Gradually a few more levees were built. Not too many years later, seven states that lie south of where the Mississippi meets the Ohio River asked the federal government for its help to check floods.
In 1882 there was a great Mississippi River flood. The government almost immediately provided $1.3 million for the improvement of the river. Part of the money was used to build new levees.
Since the late 1800s, the federal and state governments have spent many millions of dollars for the building and repair of levees.
Ordinarily, levees can be made of sandbags and banked up earth. The name comes from the French word "lever," which means "to raise."
Irrigation engineers often use the term "levee" to describe a small dike or ridge of earth which confines areas of land that are to be flooded for agricultural purposes.
Levees along the Mississippi River range from 15 to 30 feet high. Many of them are eight feet wide at the top and over 100 feet wide at the base.
More than 2,000 miles of levees have been built along the Mississippi River, but they still do not fully control the overflow. The completed long range program will have an additional 2,500 miles of levees.
About 1,500 miles of the total planned length of the levees have been built since 1905.
Some authorities object to the building of levees that enclose a river so much that the water is high above the surrounding countryside. This makes floods even more dangerous when they occur.
If a levee were to break under these circumstances, a wall of water would rush across the countryside, smashing everything in its way.
Experts who oppose high levees believe regulating floods by headwater control is better than attempting to regulate them with levees.
A jetty is a pier or wall built into a river or harbor. A jetty is used as a breakwater, to break the force of the current.
The Mississippi River carries great quantities of fine sand and silt to the place where it empties into the Gulf of Mexico. It flows into the Gulf through four mouths, called passes.
In 1874 the Mississippi River mouths were so choked with silt that steamers could not get through. It was suggested that two long jetties, which would force the water through a narrower channel, would mmake the currant carry the sand and silt out to sea.
When finished in 1879, the jetties in the South Pass provided a channel 30 feet deep.