In the early 1700s, Jean Baptist Le Moyne de Bienville planted the French flag on a bank near the mouth of the Mississippi River. On a berm above the water line, outside an acute curve, he laid out the crescent-shaped city of La Nouvelle-Orleans, or New Orleans. About a year later the little city flooded and they began building artificial levees. Henceforth, flood control and drainage have been an ongoing and expensive problem. Levees, draining the marsh and swamp land for construction and development, and oil and gas exploration and pumping have caused rapid and rampant land loss for southern Louisiana. Viewed through the lens of climate change, with warmer oceans, rising sea levels, and more frequent, exponentially stronger hurricanes, these issues are brought into clear focus.
In the late 1600s the area known today as southern Louisiana was a low-lying place on the northern shore of the Gulf of Mexico, with over 9,000 square miles of lakes, rivers, marshes, swamps and bayous. It was a hot, humid, sub-tropical territory, teeming with Native Americans, animals, and plants adapted to living in and around the brackish water. Rivers flooded often from the abundance of rain, spreading water into the surrounding marsh and bayous, and spilling out into the Gulf of Mexico. As the water flowed over the river banks, sediment also flowed out. The heavier sediment settled first, closest to the river, creating a berm and building up the banks. The lighter, finer sediment flowed out into the lower areas, delivering silt and contributing to the stew that birthed the basin and delta. Thus, the rivers themselves created the first levees around New Orleans.
As the city grew, men with shovels built earthen levees between the river and their personal property, but the fast-moving flood waters frequently undermined, or scoured this primitive protection. In 1850, The Secretary of War appointed Charles Ellet Jr, a French trained civil engineer, to survey the Mississippi River and create recommendations for planning flood prevention. He determined that building artificial embankments on the rivers caused a negative reaction as they interfered with the natural flooding and flow of sediment from the river. He also noted that on occasions of extreme rain events the levees held the water in. Foretelling the future of New Orleans, he predicted that as the building on the Mississippi River continued, the flooding would become a much larger problem. It wasn’t until many decades later that authorities began to pay attention to his assertions.
In 1910 New Orleans’ population was burgeoning and running out of dry land on which they could build. Inventor, Baldino Woods, came up with the idea to create huge pumps that could drain the marshes and swamps, diverting runoff through above- and below-ground drains and canals into the surrounding bodies of water, mainly Lake Pontchartrain. Construction exploded, and New Orleans grew like gangbusters. But the composition of the drained land was sediment, masses of plants, and organic material as much as 5 meters thick, integrated into mud. This compost is prone to consolidate and compact when it dries. The new land started to sink. (The fancy word for this situation is subsidence.) Today, over half of New Orleans is 3 – 12 feet below sea level.
Beginning in the 1930s, the oil and gas companies were dredging canals through the marshlands and laying thousands of miles of pipeline in their search for oil, becoming a destructive force along Louisiana’s now crumbling shoreline. The intrusion, and the calloused and inconsiderate way they dug, dredged, drilled, and littered the southern third of the state of Louisiana, created a veritable underwater junkyard. Requirements to fill in canals were grossly ignored. Plaquemines Parish, on one of the farthest parcels of Louisiana’s lacy fan of a coastline, was increasingly littered with old and in-use fossil fuel infrastructure.
Canals from both oil companies and the drainage system play a major role in the rapid erosion of New Orleans’ wetlands. First, salt water washes up into the canals from the ocean, inundating, weakening, and killing marsh plants that hold the coastline together. Loss of marsh allows erosion of barrier islands and The Mississippi Delta. Second, the canals divert sediment from the Mississippi River drastically decreasing the amount of sediment that makes it to the ocean where it has built and replenished these areas over thousands of years.
There has been much money made for oil and petrochemical mega-companies, and grand perks collected by crooked government officials, with no regard for the environment or the folks supported by these waters. When the BP Horizon oil well exploded in 2010, 200 million gallons of oil spewed into the Gulf of Mexico. Chemical dispersants sprayed on the iridescent slick, created tar which dropped to the ocean floor. Moving with the currents, it inundated the coastline and the spawning beds for shrimp, oysters and crabs. According to George Barisich, whose business and home were badly damaged by Hurricane Katrina and the Horizon oil spill, “They went balls to the wall with their drilling because they didn’t care. It was just money, money, money.” Currently, in Louisiana, there are 130 law suits against oil and petrochemical companies for their neglect to address the damages caused to the state and its coastline by their product and its manufacture. British Petroleum has already paid out over $60 billion in restitution with several suits yet unsettled.
By the mid-1900s new technology and construction methods allowed the Army Corps of Engineers to design concrete and steel levees and flood control for New Orleans. Poorly designed and shoddily constructed, 50 of these levees failed in 2005 as a result of the 10-28 feet of storm surge pushed up the canals, lakes, and rivers during the category 3 Hurricane Katrina. As the salt water over topped, cracked, and undermined the levees, 80% of the city
flooded along with many of the surrounding parishes. The chaos that ensued reads like a science fiction novel with houses spun off their foundations by the force of the water as it broke through the levees. The mutinous thousands of people were without food, water or medical attention for days, as children, elderly and indigents expired in the flood waters, on the sidewalks, and in their attics. Levees trapped much of the dark slurry in the city for weeks. What is now known as the worst engineering disaster in the history of the United States caused $108 billion in damages. 1,833 people lost their lives.
Katrina’s storm surge was determined to be the equivalent of a 200-year storm. As storms continue to strengthen with climate change, recommendations would have the levees built to withstand a 500-year storm surge. After spending $14.5 billion, New Orleans is now a city walled in by 133 miles of improved concrete and steel levees and flood walls, with 350 miles of canals equipped with flood gates and pumps traversing the city. Since 2005, The Lake Borgne Surge barrier and The West Closure Facility have been completed for a combined cost of $2.3 billion. Ambitious though it seems, these gargantuan structures are only designed to withstand a 100-year storm.
Driving through Plaquemine Parish along the Mississippi River, you see on one side of the road, homes, resurrected by Katrina insurance payouts, built on 20-foot-high piers. Across the road, the view for these people, is an enormous concrete 20-foot-high wall built to hold back storm surge should one be pushed up the river from the Gulf of Mexico. I’m sure the people who have been there for years are accustomed to living in the shadows of walls meant to hold out the ocean. For me it felt utterly Medieval. Like the drawbridge over the moat that surrounds the castle, the intimidating gates of the levees are built to stop the enemy when it approaches. Imagine knowing a storm is coming and being caught on the outside of the walls. Imagine being in one of the homes built up on piers when the surge over tops the walls and feeling the force of the water hitting those piers. I wonder if they will hold.
If you have enough money, perhaps it is somewhat possible to adapt and negotiate climate change. After the devastation that occurred with Katrina, the state of Louisiana’s Coastal Protection and Restoration Authority was created. Now Louisiana has a plan to rebuild her wetlands with sediment diversion from the rivers, raise levees even higher, build additional canal flood gates, and relocate her citizens or raise their homes on piers to protect them from flooding. The projected cost is $50 billion and is scheduled to begin in 2035. $20 billion of this amount was awarded from a BP oil spill settlement. They have no idea where they will find the remaining $30 billion. Ed Link, who led the Army Corps of Engineers investigation into the failure of the levee system during Hurricane Katrina, predicts that at some point residents and officials may ultimately succumb to “financial fatigue.”
As the marshlands, swamps, bayous and barrier islands erode at the rate of a football field worth of land every minute, the Gulf of Mexico comes closer and closer to New Orleans. The National Academy of Engineering and National Research Council state that levees and flood walls, no matter how sturdy or large, cannot provide absolute protection against over topping or failure in extreme events. Extreme events are becoming commonplace. 2017 saw three of the 10 most destructive hurricanes in U. S. history. Considering the most recent report by the Intergovernmental Panel on Climate Change, if the world’s CO2 emissions and other contributions to global warming are not curtailed immediately, Plaquemine Parish, outside the protective walls, will be completely underwater from 16 feet of sea level rise. Add loss of land to that and the absolute rate of sinking doubles. Link knows, without the barrier islands and wetlands, New Orleans’ defenses will also succumb to the powerful ocean. “There will be a time when you can’t build the walls high enough.” New Orleans will be drowning in the next 30 years.
Zoom in on the map above to see the many canals dug through the marsh. The subsidence is visible.