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Restore the Wetlands. Reinforce the Levees.



Understanding Louisiana’s Environmental Crisis

Waterworld.NYTM.coverEvery year Louisiana loses 25 square miles of land.
Every day, 50 acres.

After Hurricanes Katrina and Rita, people outside southern Louisiana asked why on earth (and why in hell) people would live below sea-level in a place where there is a perennial risk of hurricanes and flooding.

First of all, New Orleans’s historic, originally settled areas are not below sea level—some parts of the French Quarter are about 10 feet above sea level—but it is true that most of the 20th-century developments are.

It is also true that the sea is encroaching almost inevitably, almost irrevocably.

Louisiana was not always so vulnerable. Choctaw and other tribes lived here for millennia before the arrival of European and African settlers about 300 years ago. It is only since about the late 1920s that man-made, industrial factors—principally oil exploration and the channelizing of the Mississippi River—have caused the land to erode at a rapid and alarming pace. (It could be viewed as the ‘Gulf Coast equivalent’ of melting ice caps.)

About 1,900 square miles have disappeared in the past century, and the erosion is accelerating. Katrina tore away four years’ worth of land loss—about 100 square miles—in only a few hours. No other state in the Union has ever lost so much land. The two main causes of land loss are erosion and subsidence, or sinking—and both ultimately are caused by human actions. Erosion is caused largely by man-made canals (see below), which allow the inflow of saltwater from the Gulf of Mexico. Saltwater kills freshwater plant life. As the swamp grass dies, the roots decompose, lose their grip on the soil, and the marshy ground crumbles and sinks into seawater.

Katrina approaches the Gulf Coast, August 2005.

Subsidence. The ground is sinking because the Mississippi River has been channelized by the Army Corps of Engineers ever since the great flood of 1927. In a truly monumental achievement, the Corps built massive earthen levees a hundred feet across at the top and three hundred feet wide at the base. (These levees stood strong during Katrina.) Human settlements have been mainly safe from flooding since the river was “tamed,” but the ecological cost is that in spring the swollen waters from melted winter snows are no longer allowed to flood out across the land and deposit sediment and replenish the soil and plant life as they always did before. Over the past 7,000 years, as the Mississippi changed course every millennium or so, it built up the land of southern Louisiana through its spring floods. The Mississippi used to deposit about 85 million tons of sediment across its delta in coastal Louisiana; now all those potential minerals and nutrients are funneled straight off the continental shelf into the Gulf of Mexico where they serve no ecological benefit. And the wetlands wither, the cypress trees die, and the unreplenished lowlands sink still lower.

Since oil exploration began in southern Louisiana in the late 1920s, coastal erosion has been accelerated by oil industry pipeline canals and navigation channels. Lower Louisiana is crisscrossed by about 10,000 miles of oil and natural gas pipelines—the source of 18 percent of oil and 24 percent of natural gas supplies for the U.S. The canals trigger erosion: saltwater rushes in, burns the delicate marsh grass, and wave-action erosion beats the dying grass and roots to pieces. Because of the incursion of saltwater, the canals tend to double their width every 14 years. Scientists at LSU estimate that at least one-third of coastal erosion is directly attributable to these industrial canals. [See map of “Coastal Louisiana Land Loss from 1937 to 2000.”]

Why does it matter if the wetlands are lost—aside from the deaths of cypresses, alligators, turtles, egrets, and other swamp life? Wetlands are critical because they help absorb hurricanes’ storm surge and form a natural buffer against flooding. Scientists say about every 2.5 square miles of wetlands absorbs a foot of storm surge. Therefore, to protect against the awesome 25- to 30-foot storm surges brought by massive cyclones like Katrina and the Category 5 Hurricane Camille in 1969, for safety southern Louisiana would want (in addition to the barrier islands that have all but washed away) about 50 to 75 miles of wetlands between the Gulf of Mexico and the city of New Orleans. Environmental writer Mike Tidwell (Bayou Farewell) says that around 1900 the Gulf shore was about 50 miles from New Orleans. That distance has shrunk to only about 20 miles today, and it is closing fast. Some experts fear that if serious coastal restoration is not begun immediately, in another ten years the Gulf may be lapping at New Orleans’s suburbs.

At the same time, global warming has caused the level of the Gulf of Mexico to rise, and warmer waters intensify the ferocity of hurricanes. There is some question whether global warming causes an increase in the number of hurricanes per season, but it is known that the hurricanes spawned are strengthened by warm water—this was certainly the case with Katrina and Rita. Further, the erosion of barrier islands (the first line of defense that helps break the tidal surge) and behind them the marshlands that help absorb the tidal surge reduce the buffer zone that once helped diminish the effects of hurricanes on cities along the Gulf Coast. (Ship and Horn Islands that formerly served as a buffer for Gulfport and Biloxi have been shredded in recent decades.)

The “birdfoot” below New Orleans where the Mississippi River

The “birdfoot” below New Orleans where the Mississippi River

But All Is Not Lost—Yet

The defense of New Orleans could be envisioned as a castle or fortress ringed by three concentric walls: (1) restored wetlands to help fend off the tidal surge; (2) storm gates at the Rigolets Pass and the drainage canals between the city and Lake Pontchartrain; (3) Category 5-strength levees all around New Orleans (before Katrina the Corps of Engineers said category 3 would be strong enough; nothing has changed). In his straight-talking book The Storm, Ivor Van Heerden of the LSU Hurricane Center proposes a robust, Dutch-style flood and hurricane protection system that could be built for roughly $20 billion—about the amount the U.S. spends in three months on the wars in Iraq and Afghanistan.

Another remedy that has been proposed to help reverse coastal erosion and restore the wetlands is a 95-mile-long controlled diversion of the Mississippi around Donaldsonville, Louisiana, between Baton Rouge and New Orleans. The idea is to divert about one-third of the Mississippi’s volume westward and send its waters on either side of Bayou Lafourche (a remnant of the former path of the Mississippi) to spread the Big Muddy’s rich sediment across the wetlands north of Barataria Bay and Terrebonne Bay.

Another line of defense that engineers recommend would be a series of storm gates at the Rigolets Pass, a strait connecting Lake Pontchartrain to the Gulf of Mexico, to block the hurricane’s tidal surge from entering the lake, and at the mouths of the drainage and navigation canals around New Orleans. Storm gates have also been proposed near the juncture of the Intracoastal Waterway and the Mississippi River–Gulf Outlet (“MR-GO”) and where the Industrial Canal flows into Lake Pontchartrain. “You don’t want to let your enemy invade deeply into your territory,” explains Jurjen Battjes, a professor of civil engineering in the Netherlands. “Close your fence at the outside.” That is why Battjes and others have urged that the city’s canal pumping stations be moved to the edge of Lake Pontchartrain—and protected by the storm gates described above.

There is also a well-developed plan called “Coast 2050: Toward a Sustainable Coastal Louisiana” which details specific policy recommendations. The cost of Coast 2050 could reach about $14 billion (the U.S. spends that amount every 3 months in Iraq), but the plan could prevent the loss of about $100 billion in jobs, infrastructure, the profitable Louisiana seafood industry, and wildlife. The main practical and economic benefit, however, would be the rebuilding of the buffers against hurricanes that once existed naturally along southern Louisiana. This in turn would protect the oil and natural gas industry and the Port of New Orleans, the seafood industry, and the countless petrochemical plants in the industrial corridor between Baton Rouge and New Orleans. The Port of New Orleans is the nation’s largest in tonnage, the fifth-largest in the world. It handles some two-thirds of America’s grain and wheat—the Midwest would be crippled without New Orleans—and most of the nation’s oil and steel imports, and the minerals and raw materials feeding the industrial heartland. (See “New Orleans: A Geopolitical Prize.”)

If an enemy wanted to cripple the United States, he would strike New Orleans. As Thomas Jefferson understood when he authorized the Louisiana Purchase in 1803 (signed in Jackson Square a hundred yards from where President Bush spoke), possessing and protecting New Orleans is a matter of national security, and essential to economic prosperity.

We believe national security begins at home.

And we believe in doing something to reclaim our security.

If you want to be secure, get involved.


Enviro Reading Room

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Waiting for the Go
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