New Orleans was built above sea level, but the sinking city tries to weather Hurricane Ida

The popularity of New Orleans is not due to the fact that a very large portion of the city is built below sea level, but rather because it is a very popular city. However, hurricanes are always dangerous, particularly when they hit Louisiana.

Why would anyone build a city on ground that is below sea level? The city of New Orleans is located right next to the large Gulf of Mexico and a very large lake, the Mississippi River, creating a bowl-like geography.

The response is “They did not!” Here is the actual sequence of events.

For thousands of years, the Mississippi River transported vast quantities of sediment that had been deposited in the Northern Plains during the last ice age, into the Gulf of Mexico.

As soon as the sediment accumulated enough to create new land, New Orleans fell to the bottom and slowed down, hitting the Gulf.

During the 1800s, as the city entered its developmental phase, the fact remained unchanged: New Orleans was situated at an elevation higher than the sea, a result of the accumulation of land caused by sediment deposition whenever the Mississippi River overflowed during spring. Consequently, the land progressively rose above sea level.

The development of New Orleans

Engineers began devising methods to drain the swampland, as the populated area of the city began to expand. The proximity of the swamp to people’s residences was unfavorable, and a significant portion of the area consisted of marshland, despite the fact that the entirety of New Orleans was situated above sea level in the 1800s.

They could extract vast quantities of water from their city at any time of the day by constructing massive pumping systems.

Life was great, as the city’s pumping system protected citizens from incoming floods and hurricanes at an extraordinary pace. The city was expanding rapidly, and it was built on dry lands. As a result, businesses and homes started to emerge from the swampy areas, albeit gradually.

The sinking of New Orleans

Underneath the ocean’s surface, a mere 5% of New Orleans was situated in 1895 when circumstances began to change. Subsequently, almost 30% of the city lay below sea level by 1935, and presently over half of the city is at a lower elevation than the ocean. Enclosed by water, the city truly resembles a progressively deepening bowl.

The air pockets at the soil surface were filled to the point of sinking, and those air pockets started to sink.

The issue persists, and although there is less active drainage of swamplands, the sinking is now exacerbated by an increased presence of subterranean air pockets, which arise from the desiccation and decomposition of the organic material that was formerly present in the swamp. The situation has further deteriorated.

The process of sediment deposition and flooding along the river is being controlled by the construction of walls around it and the building of dams with sediment traps upstream. Humans have managed to halt the sediment deposition through the construction of these dams. However, the sediment that would normally be carried by the flooding of the Mississippi River can be replaced by water. The pumps in New Orleans help in filling the ground with water, which helps in preventing sediment deposition.

New Orleans is gradually transforming into a progressively deeper bowl. As a result of climate change, sea levels are increasing. Certain areas of New Orleans continue to subside at a rate of approximately two inches annually, thus exacerbating the situation.

Will it emerge victorious? Nature will inevitably prevail, but modern engineering has created incredible walls to protect against water. Nature always triumphs.

Mike Szydlowski serves as the science coordinator for Columbia Public Schools.

It’s time for a surprise test.

If the sinking persists at its current rate, how much lower than sea level will the city be after 18 years? Certain areas of New Orleans are currently situated 10 feet beneath sea level.

2. What does the sentence “nature always prevails” mean?

3. The Mississippi River created New Orleans in the remote past. Why doesn’t it assist in preserving the city’s altitude above sea level in the present day?

4. How did the act of removing water from a marsh lead to the subsidence of the city?

5. Pumping water out of the city is causing the city to continue sinking. Why don’t they just stop pumping water out?

ANSWERS TO LAST WEEK’S POP QUIZ.

1. From this article, which theories were disproven due to insufficient evidence?

The idea that predators confuse their stripes as a means of temperature regulation or identification is not supported by scientific data.

2. Why do you believe the zebra evolved mechanisms to protect against flies instead of something such as mosquitoes?

The flies must have annoyed and injured the zebras more than mosquitoes.

3. How would you arrange a test to observe if patterns deter mosquitoes from biting you?

In order to compare with a region of skin that possesses stripes, it is necessary to establish a control (like an arm lacking stripes).

4. Although it is bothersome, how could a horsefly pose a threat to a zebra?

Due to the fact that horseflies are targeting their blood, they have the capability to additionally transmit diseases.

5. How did this discovery relate to both the fields of science and history?

Researchers discovered that indigenous communities in Africa, Australia, and Asia probably adorned their skin with paint to minimize insect bites.