The Debate for a Delta

Posted from Austin, Texas, United States.

The state of Louisiana has not always looked the way that it does today. Over time the Mississippi River has caused the land to change and evolve. Today the river has been channelized to flow straight for the ease of industrial and trade boats to access the city. But it has not aways been this way, naturally the Mississippi River is a delta. A delta is a river that divides into smaller rivers and empties into a larger body of water. During this natural process, it picks up nutrients and sediments from the upper regions of the river resulting in a build up of sediment and organic material deposits at the mouth of the delta. This deposited sediment is highly rich in organic material which is important for the native wetlands and beneficial to the development of new land and crops. However with the channelization and prevention of the delta to flow naturally it has caused many environmental effects.

Currently along the Mississippi River levees have been installed to prevent the river from changing course over time. With the channelization the river has been forced to flow “straight”. This is beneficial to the city economically. New Orleans is known as one of the largest port cities in the United States. If the river was allowed to naturally divide it would result in the development of sand bars. Sand bars would inhibit the ability of cargo ships to access the city to deliver and pick up items such as food, oil, coal, and clothing. This is the reason why the levees were built to channelize the river. If the river was allowed to naturally flow into a delta it would affect the state of Louisiana economically, however the channelization is also impacting the state environmentally.

The citizens of Louisiana have been depleting the land of its rich resources over the last 120 years. As a result, major environmental consequences have occurred such as the degradation and loss of wetlands, decrease in water quality, and land loss. Loss of wetlands have occurred because the channelization of the river has caused it to flow faster and thus not allowing it to divide and disperse its rich sediments. This sediment is an important contributor to wetlands because it accommodates increase land mass and organic materials increasing the ability of wetlands to act as a storm buffer. In addition, man has removed a great amount of the wetland Cypress trees for the use of lumber. Without the presence of cypress trees, the land of Louisiana is more vulnerable to the effects of wind and flooding. Cypress trees are known for their ability to absorb copious amounts of water and act as a wind buffer. Furthermore, the channelization of the river has affected levels of salinity within the estuaries. This means that the oysters have migrated closer towards the shores. As a result, industries have taken advantage of this change and are now harvesting oysters at alarming rates. Oysters are important for their ability to filter water, their loss within the ocean has therefore decreased the overall water quality within the surrounding gulf. Not only does this affect water quality but the ability of the wetlands to survive. The most important environmental effect caused by man is land loss. Land loss is a consequence of the channelization of the river. Channelization due to the installation of levees has caused a choking effect down river causing water levels to rise and speed to increase. The increased water speed has prevented the river to naturally slow and disperse sediments evenly over the land. Furthermore inhibiting the build up of sediments to support the growth of wetland ecosystems and the surface area  of the land. All of these factors put together have contributed to the devestating  effects of Hurricane Katrina.

To prevent a repeat of what happened during the storm of Hurricane Katrina, Louisiana has installed a system that is called siphons. Siphons are large pipes that when turned on will pull nutrient and organic rich sediment out of the Mississippi River and push it into nearby wetlands. The goal of this project is to replicate mother natures ability to disperse sediment naturally, just as a delta would. The problem is that these pipes are rarely ever turned on. Some think that the restoration of of these wetlands will be detrimental the city economically. While others think that it is necessary to keep the city above water. However the larger problem in this situation seems to be the debate over whether it is more important to save the city economically or the ecosystem. But what most people do not realize is that without a well balanced and functioning ecosystem, there will be no city.

  • Katie and Hayden

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