'Big Easy' a bowl of trouble in hurricanes
By James West, USATODAY.com
With the 2000 hurricane season entering its most fierce stage, should the "Big Easy" change its nickname to the "Big Worry"? Officials there who plan for hurricanes think so.
The last time a major hurricane – with winds over 111 mph – came close to New Orleans was Hurricane Camille in 1969, says Paul Trotter, chief of the National Weather Service office in nearby Slidell, La. That storm came ashore about 55 miles east of New Orleans in Mississippi. Trotter says that there have been 12 or 13 major storms to hit within 85 miles of New Orleans in the last 120 years, or an average of one major hurricane occurring once a decade.
"With Camille hitting over 30 years ago, we are well overdue for a major one," Trotter says.
New Orleans, a city of nearly 1.4 million people, sits below sea level, as much as 8 feet lower than water in nearby Lake Pontchartrain and the Mississippi River and its delta, where it empties into the Gulf of Mexico. This in effect creates a "bowl" that floodwaters can settle into, like water headed for a stopped-up drain.
To combat this unique problem, a system of levees surrounds the city to hold back the waters of Lake Pontchartrain to the north and the Mississippi River to the south, says Joseph Suhayda, director of the Louisiana Water Resources Research Institute at Louisiana State University in Baton Rouge. The levee that holds back Lake Pontchartrain is 15 feet high while the one guarding against the Mississippi River is 20 feet tall.
Suhayda says the 15-foot levee will protect the city from a minimum hurricane of Category 1 or 2 intensity and at best a fast-moving Category 3 hurricane on the Saffir-Simpson hurricane intensity scale.
"A slow-moving Category 3 or any Category 4 or 5 hurricane passing within 20 or 30 miles of New Orleans would be devastating," Suhayda says.
The storm surge — water pushed into a mound by hurricane winds — would pour over the Pontchartrain levee and flood the city. A severe hurricane could push floodwaters inside the New Orleans bowl as high as 20-30 feet, covering most homes and the first three or four stories of buildings in the city, he says. "This brings a great risk of casualties."
In this type of scenario the metro area could be submerged for more than 10 weeks, says Walter S. Maestri, Director of Emergency Management for Jefferson Parish, which encompasses more than half of the city. In those 10 weeks, residents would need drinking water, food and a dry place to live.
Besides the major problems flooding would bring, there is also concern about a potentially explosive and deadly problem. Suhayda says flooding of the whole city could easily mix industrial and household chemicals into a toxic and volatile mix. Coupled with an estimated 100,000 tons of sediment, a cleanup could take several months. In the worst case scenario, the mix of toxic chemicals could make some areas of the city uninhabitable. "It could take several years for the city to recover fully, economically, from a strong hurricane," says Suhayda.
To make residents aware of the dangers New Orleans faces, Maestri and his staff visit churches, professional organizations and social clubs almost every week of the year to discuss the risks. They distribute videos to schools, libraries and even to video stores for free distribution to the public. They also provide information to the commercial mass media to make the public aware.
Maestri says that the public knows and understands the threat they face if a major hurricane was to strike near New Orleans. For instance, when Hurricane Georges threatened the Gulf Coast in 1998, an estimated 60 percent of the New Orleans population evacuated the city, Maestri says. It was the largest evacuation in U.S. history at the time, according to the National Weather Service. Even then, not everyone could get out, and the Louisiana Superdome in New Orleans was used as a shelter for the first time. Fortunately for the city, Hurricane Georges, a Category 2 hurricane with winds near 110 mph, landed to the east in Biloxi, Miss.
Despite the difficulty in getting everyone out, Maestri says evacuation is the best policy for a city under sea level and not fully protected from storm surge and flooding. But he is concerned that he still might not have enough advance warning to evacuate all of New Orleans. Improvements in hurricane predictions during the last 30 years have made it possible for the National Hurricane Center to issue hurricane warnings 24 hours ahead of when a storm hits. But, Maestri says it takes nearly 72 hours to fully evacuate New Orleans. This means that an evacuation order must be issued using a forecast that could have an error of 150 miles. While Maestri and his team are busy evacuating the city, the storm could be heading for Alabama and Mississippi to the east or the bayous of western Louisiana instead of New Orleans.
An evacuation could create a ghost town unnecessarily and make people more complacent when the next hurricane nears the Gulf Coast. Maestri is also concerned that he could be placing evacuees in the path of danger if a storm struck along the evacuation routes instead of New Orleans.
Besides getting everybody out, Suhayda says there are two alternate solutions that would protect people from potential flooding if a category 4 or 5 hurricane were to hit the city. The first would be to raise the levees, especially the one bordering Lake Pontchartrain. Raising the lake levee to the 20-foot height of the Mississippi River levee should give enough protection for the city. Another solution, the so-called "haven plan" by Suhayda, would involve building an internal levee that would protect the city's core; hospitals, government buildings and transportation as well as the electrical and water infrastructure would be safe from the ravages of a flood.
But the two plans involving the building of new levees are massive and expensive public works projects, Suhayda says. They would take more than a decade to plan and build, he concludes, leaving the city with no improvement to its hurricane problem in the near future.
"Residents will have to deal with a threat of flooding for at least the next 10-15 years."
Contributing: Chris Vaccaro, USATODAY.com
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