Hard Choices for the Big Easy

By Larry Smith

"And every time we think about the bacon and the beans, we'll think about the fun we had way down in New Orleans."
Jimmy Driftwood

Why did Katrina trash New Orleans?

Well, it actually had nothing to do with either divine retribution or George Dubya, and everything to do with geography.

In fact, this was the most anticipated disaster in history. Officials have spent years planning for just such an event. And computer models developed at Louisiana State University and other institutions made detailed (and accurate) projections of what would happen in a major storm.

Ultimately, the havoc was caused by human impact on the area's natural ecosystems. New Orleans lies an average eight feet below sea level, spread over miles of flood plain in the Mississippi River delta. As a result, more than 80 per cent of this historic city was flooded by Hurricane Katrina.

The eye of Katrina came ashore between New Orleans and Biloxi, pushing a wall of water eight to 30 feet above sea level. The storm surge drove into Lake Pontchartrain, overwhelming levees and canals, and flowed into the city.

But it was not at all unexpected. Four years ago, for example, Scientific American ran an article called 'Drowning New Orleans', which said a major hurricane strike would swamp the city under 20 feet of water and kill thousands.

Ole Man River

The Mississippi delta is the largest expanse of coastal wetland in North America - built by the sediment-rich waters that drain to the river from 31 US states and three Canadian provinces. This fertile ecosystem produces 30 per cent of America's total fish catch.

Native American hunter-gatherers inhabited the delta for thousands of years, but there was no significant settlement until the French founded New Orleans on a bit of high ground in 1718 . Louisiana was a French colony until Napoleon sold it to the United States in 1803 for $15 million.

The Mississippi drainage basin is home to more than a million people and critical to the vitality of the Gulf of Mexico ecosystem. The basin supports a variety of industries, but has always posed a flood threat. This is part of nature - the annual spring floods spread fresh silt across the delta, supporting the marshes and building up the land.

People have been trying to tame the river since the 19th century. But after Hurricane Betsy in 1965, hundreds of millions of dollars were spent to upgrade the flood control system that now includes miles of levees, floodgates, pumping stations and drainage canals. While this reduced the risk to people and property , it also encouraged new development in flood-prone areas.

Today, the city of New Orleans lies in a shallow depression surrounded by levees 15 to 25 feet high. This system is one of the most extensive in the world - over 100 miles of earthen banks hemming in the mighty Mississippi and Lake Pontchartrain.

The dikes were designed to withstand a moderate (Category 3) hurricane surge. According to some estimates, their failure would cost the city and surrounding areas $25 billion in property losses and tens of thousands of deaths by drowning. But after Katrina, insurance losses are put at $60 billion, dwarfing Hurricane Andrew which caused nearly $21 billion in claims. The death toll has yet to be calculated.

New Orleans became an important city because the system of rivers that flowed through the American Midwest all ran into the Mississippi, which flowed to the ports in and around the delta. These ports shipped America's rich agricultural surplus to the rest of the world.

More recently, oil and natural gas have helped fuel the area's prosperity, which still accounts for about a third of domestic US production. The local refineries are critical to American infrastructure, and the offshore port receives about 15 per cent of US oil imports. In fact, Louisiana's port system is America's biggest shipping facility.

Causes of Catastrophe

This strategic position spurred massive growth and development, which produced the environmental disaster precipitated by Katrina that we just witnessed. Experts point to four main causes:

First, dams and levees along the river reduced water flow and funnelled marsh-building sediments away from shore. Controlling the flooding lowered the water table in the delta, allowing the surface to dry out and subside. The city is sinking three feet per century.

Second, the removal of millions of barrels of oil, trillions of cubic feet of natural gas, and tens of millions of barrels of water lying with the petroleum deposits caused a drop in subsurface pressure. That led nearby underground faults to slip and the land above them to slump.

Third, more than 8,000 miles of canals were cut through the coastal marshes for oil exploration and ship traffic. This increased erosion and allowed salt water to infiltrate and kill freshwater marshes, leading to more erosion. The shoreline is receding at 30 feet a year.

Fourth, the delta's low-lying barrier islands are disappearing. According to Scientific American, "A century ago these mangrove-covered islands were part of the region's shoreline. They broke up ocean waves, cut down storm surges and held back saltwater so the marsh behind it could thrive. Now the ocean rushes right by."

So in 1998, State and Federal officials devised a plan called Coast 2050 to restore healthy natural processes. Over a decade, this massive, multi-billion-dollar effort aimed to recreate the marshes and reconnect the barrier islands to reduce the impact of surges. But unlike the Florida Everglades restoration, it was never funded.

The plan's main strategies are watershed management such as river diversions into swamps, and restoration of barrier islands combined with strengthening of the levee/canal system. Had it been implemented, parts of the city might have been saved, experts say. However, the Coast 2050 plan may now be funded by Congress in the wake of the disaster.

According to Louisiana State University geography professor Craig Colten, "it would be foolish to try to rebuild New Orleans as it was. We need to find ways to put some of those lowest-lying areas into a wetlands type of land use."

Without action, experts say the million people outside New Orleans would have to relocate: "The other million inside the bowl would live at the bottom of a sinking crater, surrounded by ever higher walls, trapped in a terminally ill city dependent on non-stop pumping to keep it alive."

There are many lessons for Bahamians to learn from this tragedy.