Doomed New Orleans: Hurricane Katrina | National Geographic

Summary

This video explains how Hurricane Katrina’s devastation was both a natural and man-made disaster: New Orleans has long been sinking because its soil compacts and, since levees keep the Mississippi River’s silt out, the land no longer receives renewing sediments. At about 3 feet per 100 years and with some areas 8 feet below sea level, the city is increasingly vulnerable to storm surge. Surrounding wetlands — which absorb storm energy — are vanishing due to canals, erosion, and sediment loss (over 1,900 sq miles lost since 1930). Without restoration, New Orleans and nearby barrier islands face growing risk of slipping beneath the sea.

Takeaways

• 😀 Hurricane Katrina devastated New Orleans, submerging entire neighborhoods under 20 feet of water.
• 🌍 New Orleans has been sinking since its early days due to the nature of its soil, a mixture of silt, sand, and clay.
• ⛔ The Mississippi River’s natural flooding once replenished the sinking land with fresh silt, but levees have stopped this natural process.
• 🏙️ New Orleans is currently sinking at a rate of 3 feet every 100 years, and some parts of the city are already 8 feet below sea level.
• 🌧️ The risk of future flooding is increasing, especially with the continued sinking of the city and surrounding areas.
• 🌿 Wetlands around New Orleans are also disappearing, adding to the city's vulnerability to flooding.
• 💧 Every hour, Louisiana loses about 2 acres of wetlands, which are essential for absorbing storm surges and protecting the city.
• 🏝️ Levees, while designed to protect New Orleans from rising river levels, have ironically contributed to the erosion of wetlands by blocking the flow of silt into the area.
• 🛑 Wetlands, not levees, act as the primary defense against hurricanes by absorbing storm surges, with every 3 miles of wetland absorbing one foot of storm surge.
• 🗓️ Since 1930, Louisiana has lost over 1900 square miles of wetlands, and by 2050, many barrier islands may disappear entirely, further threatening New Orleans.
• 🌊 Unless action is taken, New Orleans will continue to sink and may eventually be submerged, regardless of future hurricanes.

Q & A

What natural disaster is described as one of America's worst in the transcript?

Hurricane Katrina is described as one of America's worst natural disasters, causing massive devastation in New Orleans.

Why is New Orleans sinking, according to the script?

New Orleans is sinking due to the combination of silt, sand, and clay in the soil, which compacts over time. The city's land is sinking at a rate of 3 feet every 100 years.

What role did the Mississippi River play in preventing New Orleans from sinking before its development?

Before New Orleans was developed, the Mississippi River regularly flooded, depositing fresh silt that replenished the sinking land and kept the area above sea level.

How do the levees around New Orleans contribute to the sinking of the city?

The levees around New Orleans keep the river out, but they also block the flow of silt and sediments, preventing the land from being replenished, which accelerates the sinking of the city.

What is the current rate of land subsidence in New Orleans?

The current rate of land subsidence in New Orleans is approximately 3 feet every 100 years.

How much of New Orleans is currently below sea level?

Parts of New Orleans are currently 8 feet below sea level.

Why are the odds of another flood increasing in New Orleans?

The odds of another flood are increasing because the ground under New Orleans is sinking, and the surrounding wetlands, which act as a natural barrier, are also disappearing.

What role do wetlands play in protecting New Orleans from hurricanes?

Wetlands act as a natural barrier, absorbing storm surges. Every 3 miles of wetland can absorb a foot of a storm surge, providing significant protection against hurricanes.

What is causing the loss of wetlands in Louisiana?

The loss of wetlands is largely due to human activity, including the construction of canals, which increase erosion, and the building of levees, which funnel silt out into the Gulf, preventing it from replenishing the wetlands.

How much wetland area has Louisiana lost since 1930?

Since 1930, Louisiana has lost over 1,900 square miles of wetlands.

What is expected to happen to the barrier islands in Louisiana by 2050?

By 2050, many of the barrier islands in Louisiana are expected to disappear entirely.

What is the long-term outlook for New Orleans if no action is taken?

If no action is taken, New Orleans will continue sinking and may eventually slip beneath the sea, even without another hurricane.