HEI Impacts

Re-Routing the Mississippi River

Over time, the Corps of Engineers has altered the course that the Mississippi River takes on its way to the Gulf of Mexico. This was done for many reasons: it was an attempt to limit flooding, to assist with shipping channels, and to allow for the pipelines required for oil and gas exploration. the energy infrastructure. To allow for this, they had to cut off certain tributaries that went out of the Mississippi and make the main river wider and deeper.
As a result of what the Corps of Engineers has done, the coast of Louisiana is eroding away. The soil there is no longer as fertile as it once was because salt water is making its way farther inland. The tributaries of the Mississippi used to make the dirt able to support many types of life. But now that they're gone, trees have a harder time growing there. With less trees, the soil is not firmly packed together and is more likely to blow away. When hurricanes and other storms hit the coast of Louisiana, the soil cannot resist against them and so wears away even more. Entire barrier islands that used to be along the coast have now been completely eroded. Without the coastline there, salt water is moving farther inland, and the trees that are still surviving usually die because they can't tolerate salt water. It is estimated that the Mississippi River Delta loses roughly a hundred yards of land an hour. If we don't find a way to undo the results of the re-routing of the Mississippi River, then the entire Louisiana coastline will be eroded away and all the cities close to the Gulf will be more at risk from hurricanes.

Restoring Barrier Islands

People have finally recognized this problem and they've attempted to fix it by constructing man-made barrier islands. They dig up sand and sediment from the ocean floor several miles offshore and then pipe it in to the shoreline. Then they use equipment to move it around to shape the man-made barrier island and sometimes plant vegetation to help anchor the soil. But this presents new problems as well. As with any time that man tampers with nature, the intentions are good, but there can still be unintended consequences. These barrier islands protect fragile breeding grounds for many species of fish and other wildlife. Changing the barrier islands shape can subtly alter the current, leading to changes in salinity and other effects on these breeding grounds. These factors have to be constantly monitored when rebuilding the barrier islands to make sure we don't create new problems while fixing the old ones.

How they're related

We increased erosion of coastal areas through altering the course of the Mississippi River. That problem has finally been recognized. However, our man-made attempt to rebuild barrier islands presents its own challenges as well and can significantly impact fragile coastal ecosystems.


1. Why are people constructing barrier islands?

2. How are we most affected by the alteration of the course of the Mississippi River?