El Nino adds to Louisiana’s coastal threats
16th November 2015 · 0 Comments
By Susan Buchanan
Contributing Writer
Storm surges and flooding this fall in Orleans and parishes nearby and further south can be partly blamed on El Nino. This weather event is believed to be the most intense of its kind since 1997 or earlier, posing another hazard to Louisiana’s coastline. Since the 1930s, the state’s coast has lost beaches and protective wetlands equivalent in size to Delaware.
New Orleans and vicinity won’t have a typical winter this year. “You guys in south Louisiana will see a wet, stormy pattern from now into February,” Bob Smerbeck, senior meteorologist at AccuWeather in Pennsylvania, predicted last week. “Because of the precipitation and clouds, your temperatures could be one or two degrees below normal.”
A cow seeks shelter from the flooding in Plaquemines Parish caused by Hurricane
Isaac in 2012.
Photo courtesy of P.J. Hahn, Pelican Coast Consulting
Because El Nino enhances hurricanes in the Pacific, the north-central Pacific region has suffered through a record number of hurricanes and other storms this year.
In Orleans and vicinity, strong winds as Patricia moved through last month caused power outages. A levee in Myrtle Grove in Plaquemines Parish was breached. Lakeshore Drive in Mandeville was closed to flooding for five days, and properties nearby were inundated. “Fifty to 100 years ago, that road would have stayed dry,” Lopez said. “But the sea level’s rising, and the land’s subsiding and getting more porous.” Subsidence is the settling or sinking of the earth’s surface.
This year’s El Nino has been compared to a mega-event in 1997, when the southern and southeastern United States were flooded. El Nino typically hits the nation hardest in the winter as cold air from the arctic heads south and bumps into warm air in the tropics. Warmer-than-usual water off the coast of South America shifts the storm track. A cold storm track lingers over Canada while a warm, wet trajectory moves south to California. That triggers a wet pattern for most of California through Texas and Louisiana and into Florida, sometimes extending to springtime.
With south Louisiana’s relatively low evaporation rates in the fall and winter, soils can stay soggy during El Nino. Rivers and other waterways can rise in only moderate rainfall, causing flooding.
As El Nino and other factors impact winds, this fall’s Gulf blasts from the southeast caused flooding in October around Lake Pontchartrain and in St. Bernard Parish. AccuWeather’s Smerbeck said tropical systems can push up from the southeast in a northwesterly direction through Lakes Borgne and Pontchartrain. “Winds funnel up between Mississippi’s coast and the Mississippi River and cause tidal accumulation,” Lopez said.
Showers and winds have been double whammies. “Flooding here this fall was a combination of several things, including the large amounts of rain we received,” St. Tammany Parish spokesman Ronnie Simpson said last week. “The major compounding issue was a strong and constant wind from the southeast that pushed water into Lake Pontchartrain and caused it to pile up along the coast.”
Weather events have more severe consequences now than they would have in the past, P.J. Hahn, president of Pelican Coast Consulting in New Orleans and a former coastal zone director for Plaquemines Parish, said. “People in Plaquemines who got through Katrina and other major hurricanes were shocked at the destruction from Isaac in August 2012,” he said. Isaac entered southeast Louisiana as a category 1 hurricane. “With a storm surge of 18 to 20 feet, Isaac did more damage in Plaquemines than Katrina,” he said. Minor storms are increasingly dangerous as the coast becomes more vulnerable. “Seas are rising and coasts are shrinking around the world, but south Louisiana has the highest rate of subsidence anywhere,” Hahn said.
As for El Nino, a second straight year without a major hurricane has lulled Louisiana residents into a false sense of security, Hahn said. “We should be working on coastal restoration projects 365 days a year, not just studying them.” But it takes a hurricane to galvanize restoration activity. Newly rebuilt levees, particularly in Orleans, have made people more complacent too, he said. “But the east bank of Plaquemines and the lower end of that parish, the west bank of Jefferson, along with Lafitte, Grand Isle, parts of Lafourche Parish and anywhere along the coast, are under protected and susceptible to storm surge and flooding,” he said. As it waits for more federal and state assistance, Plaquemines Parish is doing levee rebuilding on its own now, he noted.
Beyond weather impacts, the Plaquemines coast and its marshes are still recovering from oil spilled by BP in 2010. “We don’t know the full effects of that oil on the wetlands, wildlife and seafood yet,” Hahn said. “Louisiana got 92 percent of the BP oil that was collected, and Plaquemines Parish got a third of that.” Oil caused some of the land in Plaquemines to erode and become open water. And weathered BP crude is still found in the parish’s Bay Jimmy. Oyster beds on the east bank of Plaquemines are barren now.
BP’s overall spill settlement, totaling $20.8 billion with $6.8 billion for Louisiana, was disappointing. Plaquemines rejected the offer it received as too low to compensate for coastal damages and administrative expenses. The federal fine for barrels spilled could have been anywhere from $1,100 for a statutory penalty and up to $4,400 for gross negligence. “BP was fined on the low end at $1,700 a barrel,” Hahn said. The state of Louisiana and local jurisdictions are using funds from the BP settlement for coastal projects now. But they had banked on larger penalties that would have allowed them to do more sooner. Louisiana has been losing more than 16 square miles of coast a year.
Last week, the National Oceanic and Atmospheric Administration predicted that El Nino will peak this December, based on the warmth of equatorial Pacific waters. That won’t be the event’s end, however. In the United States, El Nino’s impacts are typically strongest from December to March, the agency said. Meanwhile, this year’s conditions have scorched Southeast Asia, and Indonesia’s forest fires have been the worst since 1997.
This article originally published in the November 16, 2015 print edition of The Louisiana Weekly newspaper.
