how frequent are major changes of course in the lower mississippi

Full Answer

How often does the Mississippi River change course?

The Mississippi River has changed course to the Gulf every thousand years or so for about the last 10,000 years. Gravity finds a shorter, steeper path to the Gulf when sediments deposited by the river make the old path higher and flatter. It’s ready to change course again.

What are the factors that affect the flow of the Mississippi?

The main factor is energy. The Mississippi is a very curvy, knowns as meandering, river. As the water flows through each of these meanders, there is a difference in the rate of flow between the inside and the outside of the meander.

Why does the Mississippi River change its shape?

This allows for the growth of meanders and the change in shape for the river. Eventually, as silt and sediment clog the rivers main channel, the river will rise, ultimately switching channels, finding a path that is steeper and more direct in its path to the Gulf of Mexico, beginning the cycle all over again.

How often does the Mississippi River flood?

Floods are becoming more frequent, longer, and higher — even though average annual rainfall in the Mississippi drainage basin has been almost flat since 1940. It has flooded every other year on average since 1972 vs. once every six and a half years 1940-72.

How many times has the Mississippi river changed course?

The Louisiana coast has been built over the last 7,000 years by the Mississippi River changing course and creating six different delta complexes. Before the extensive levee system that “trained” our river to stay in one place, the Mississippi changed course about once every 1,000 years.

Did an earthquake changed the course of the Mississippi?

One of the world's most powerful earthquakes changed the course of the Mississippi River in Missouri and created Reelfoot Lake in Tennessee while shaking parts of Arkansas, Kentucky, Illinois and Ohio.

Why did the Mississippi river changed course in 1876?

U.S. Grant attempted to dig a canal to bypass Vicksburg, the Mississippi River changed its course and accomplished what the Union general could not.

When did the Mississippi river change its course?

Many of these abandoned meanders provide important marshland wildlife habitat. The last major change to the river's course in the Vicksburg area occurred in 1876. On April 26 of that year, the Mississippi River suddenly changed courses, leaving Vicksburg high and dry.

Will the Mississippi river change course?

The Mississippi River has changed course to the Gulf every thousand years or so for about the last 10,000 years. Gravity finds a shorter, steeper path to the Gulf when sediments deposited by the river make the old path higher and flatter. It's ready to change course again.

How has earthquakes affected Mississippi in the past?

Since its admission into the Union in 1817, Mississippi has had only four earthquakes of intensity V or greater within its borders. Although the number of earthquakes known to have been centered within Mississippi's boundaries is small, the State has been affected by numerous shocks located in neighboring States.

How do rivers change course over time?

So along the inside of the curve, sediment gradually gets deposited as it settles out of the slower-moving water. Along the outside of the curve, more sediment stays suspended, and some of it scrapes against the riverbank, carving out the curve further.

How far has the Mississippi River changed over time?

Left to their own devices, rivers change course over time, and the Mississippi is no exception. Geologists surmise that the Mississippi changed course numerous times over the past 10,000 years, wandering across a roughly 320-kilometer (200-mile) range along the Gulf Coast.

How many times has the Mississippi avulsed?

The real world agrees: The Mississippi has avulsed in central Louisiana about once every 1400 years, creating large delta lobes across the Gulf Coast. The researchers also found evidence for repeated avulsions one backwater length up from the mouth of the Yellow, Rhine, Danube, Orinoco, and Nile rivers.

How has the Mississippi river delta changed over time?

Today, the Mississippi River Delta's natural cycles of change and rebirth have been constricted by human activities such as leveeing of the river for navigation and flood control, laying the groundwork for today's ecological collapse and land loss.

How much has the Mississippi river moved?

1, it has dropped more than half its original elevation and is 687 feet (209 m) above sea level. From St. Paul to St. Louis, Missouri, the river elevation falls much more slowly and is controlled and managed as a series of pools created by 26 locks and dams.

What is the course of the Mississippi river?

Rising in Lake Itasca in Minnesota, it flows almost due south across the continental interior, collecting the waters of its major tributaries, the Missouri River (to the west) and the Ohio River (to the east), approximately halfway along its journey to the Gulf of Mexico through a vast delta southeast of New Orleans, a ...

How long has the Mississippi River changed course?

The Mississippi River has changed course to the Gulf every thousand years or so for about the last 10,000 years. Gravity finds a shorter, steeper path to the Gulf when sediments deposited by the river make the old path higher and flatter. It’s ready to change course again.

What is the effect of floods on the Mississippi River?

The higher the hill, the greater the “head” or force driving the flow. Floods on the Mississippi raise the water level inside the levees and increase this force. Floods are becoming more frequent, longer, and higher — even though average annual rainfall in the Mississippi drainage basin has been almost flat since 1940.

Posted November 22, 2012

Did you ever hear the saying, "it's easier to get the Mississippi to change its course than get a stubborn child to change his mind"? I guess whoever made this one up didn't know that the Mississippi actually does change its course about every thousand years or so.

Changing Direction

How could a river change its course? Actually, the whole process is due to silt. Every year, erosion from farm fields and building projects washes millions of tons of soil into streams and rivers.

Clogged Up

Over the past eight thousand years, the Mississippi's main channel has become clogged up and changed course at least seven times. Under natural conditions the city of New Orleans should now be underwater, but this has been prevented by the Army Corps of Engineering's spending millions of dollars to prevent the Mississippi from changing course.

What would happen if the Mississippi River changed course?

A course change in the Mississippi would severely impact the oil industry, shipping and fisheries industries.

How much material has been dredged at the mouth of the Mississippi River?

According to U.S. Army Corp of Engineer’s Col. Michael Clancy more than 30 million yards of material has been dredge at the mouth of the Mississippi river, an amount that the river replaces in 11 minutes. Photo: Facebook. According to U.S. Army Corp of Engineer ‘s Col. Michael Clancy, New Orleans District Commander, ...

What are the sand bars on the Mississippi River?

The sand bars currently clogging the Mississippi are depositional features of sediment reducing flow power. They are similar to small islands and an important part of the life cycle of the river. These formations continue to form along the river’s path.

How much of the Louisiana Delta has been lost since 1932?

Since 1932 almost two million acres of the Louisiana delta plain has been lost, as the Louisiana Gulf coast has experienced one of the highest rises in sea level over the past century. There is one possible positive effect from the 150-mile course change into the Atchafalaya according to Xu. “The Delta will grow very fast.

Is the Mississippi River correcting the Atchafalaya?

Mississippi River Course to Correct to Atchafalaya According to LSU Professor. The Mississippi River is trying to change course into the its historic Atchafalaya Basin channel accordingDr. Jun Xu, a world-renowned hydrologist and Professor of Hydrology of Louisiana State University’sSchool of Renewable Natural Resource.

Who designed the Old River Control Structure?

When the Old River Control Structure was designed, Hans Albert Einstein, son of Albert Einstein and Professor of Hydrology at the University of California – Berkeley, was a consultant on sedimentation hired by the U.S. Army Corp of Engineers.

Is the Mississippi River changing course?

The Mississippi River is trying to change course into the its historic Atchafalaya Basin channel according to Dr. Jun Xu, a world-renowned hydrologist and Professor of Hydrology at Louisiana State University’s School of Renewable Natural Resource, in a recently released video on Bigger Pie Forum. A course correction Xu says is not a matter ...