As the Mississippi River enters the Gulf of Mexico, it deposits its load of sediment in a delta.
Click on image for full size
Changing the Mississippi River Could Lead to New Land near New Orleans
News story originally written on October 20, 2009
The land around New Orleans, Louisiana has been sinking. At the same time, sea level has been rising because of global warming. These changes have caused large areas of land to disappear into the ocean.
Scientists have discovered how to build-up new land in an area by rerouting water from the Mississippi River. They used computer models to study how the river carries sediment and deposits it in areas where the flowing water slows. The build up of sediment creates land.
The delta of the Mississippi River has been losing about 44 square kilometers (17 square miles) each year since around 1940.
Why is land disappearing so fast? Ever since levees were built below New Orleans decades ago to prevent the Mississippi from flooding, the amount of sediments eroded has been greater than the amount of sediments deposited. This is because the levees allow river water to flow faster. The water is moving too fast to drop the sediments it carries and build up the land. Instead it drops the sediments far out into the ocean.
The scientists’ model looks at how diverting the river water through two openings in the levees would affect the land 150 kilometers (93 miles) from New Orleans. Nearly half of the river's water would spill out through the openings. The water would slow down beyond the levees, depositing sediment and helping to build up the land.
The changes to the river's path would not solve the problem of disappearing land in the New Orleans area, but they would help slow the loss of land. Scientists estimate that the amount of new land created would be up to 45 percent of the area that will be lost over the next 100 years.
Last modified January 21, 2010 by Lisa Gardiner.
Shop Windows to the Universe Science Store!
Our online store
includes fun classroom activities
for you and your students. Issues of NESTA's quarterly journal, The Earth Scientist
are also full of classroom activities on different topics in Earth and space science!
You might also be interested in:
Measuring sea level, the height of the ocean surface, allows scientists to calculate whether sea level is changing over time and how much sea level rise is happening now because of global warming. But...more
Earth’s climate is warming. During the 20th Century Earth’s average temperature rose 0.6° Celsius (1.1°F). Scientists are finding that the change in temperature has been causing other aspects of our planet...more
If you sneeze into a pile of dust, the little particles fly everywhere. But if you sneeze into a pile of rocks, they will stay put. It takes more force than a sneeze to move those rocks. Winds and water...more
When water or wind loses energy and slows down, sediment can no longer be carried in it. The particles fall through the water or air and form a blanket of sediment on the bottom of a river, a lake, ocean,...more
Rivers are very important to Earth because they are major forces that shape the landscape. Also, they provide transportation and water for drinking, washing and farming. Rivers can flow on land or underground...more
Scientists have learned that Mount Hood, Oregon's tallest mountain, has erupted in the past due to the mixing of two different types of magma. "The data will help give us a better road map to what a future...more
The Earth's mantle is a rocky, solid shell that is between the Earth's crust and the outer core, and makes up about 84 percent of the Earth's volume. The mantle is made up of many distinct portions or...more