Hurricane season comes with uncertainty

Published 12:00 am Saturday, May 28, 2011

By Baileigh Rebowe


LAPLACE — With hurricane season officially starting on Wednesday and running until Nov. 1, most are starting to question what will happen if a hurricane arrives with high water levels in the river and the lake.

Steve Wilson, president of the Pontchartrain Levee District gave voice to the biggest fear of many. He said he does not want to see a hurricane make landfall before the river water has the chance to go down.

He said there is certainly no room for tidal action upriver.

“ It would be something like ‘The Perfect Storm,’ said Wilson. Wind can push water over levees as we saw when (Hurricane) Katrina happened. Anything that comes can push it high.”

Although the levee districts are confident in river levels right now, it would not be good timing for any kind of major storm, Wilson added.

He said the U.S. Army Corps of Engineers has been upgrading levees from Algiers southward but work was shut down recently because of high water levels. It can’t resume work until the water is below 15 feet, so if a hurricane would come the corps would have to bring out temporary measures like HESCO baskets and temporary levees.

Wilson said river levees from Baton Rouge to the Jefferson Parish line have never been affected by any hurricane, so he is more worried about the effects from Lake Pontchartrain for the River Parishes area.

“I don’t have any fear, besides wave action, for the river in this area (if a hurricane came). I am more concerned with lake tidal surges because levees have not finished being built yet,” said Wilson.

Robert Ricks, meteorologist with the National Weather Service, agreed with Wilson, saying the possibility of surges in the river and lake produced by these strong winds should be of concern.

“I can see some overlap of wave action happening if a hurricane were to come, but to what extent it’s really hard to say,” said Ricks.

During Hurricane Gustav waves created by higher wind pushed water over the floodwall onto the street, and that is most likely to happen if a hurricane were to form today, Ricks explained.

He said the rise in water levels in the river from a hurricane or tropical storm would probably be of a lesser hazard than the wind.

This is because water seeks its own level. One side of a body of water cannot be higher than the other, and the two opposing levels will work to be in equilibrium when excess water is obtained, Ricks made clear.

“It’s like when you have a 17-foot level of water and you receive 14 feet. The water will not reach a 31-foot level but rather level off, resulting in maybe a one- or two-foot rise on top,” Ricks said.

It can also be seen when one pours water into a u-shaped pipe. The water level is the same in both sides of the pipe even if more water is poured into the right side, making it rise. The left side will adjust accordingly and rise, too.

He mentioned an extreme rise in river water levels can happen, but it is not always the case.

According to Ricks, this conclusion is based on simulations and tests run by the lower Mississippi River forecast center in New Orleans. The center uses models of past hurricane action when river levels were high to form hypotheses on how the river would react if a storm were to come in the next month. The team chose to simulate Hurricane Ida in 2009 when river levels were affected.

“The simulations showed that a Category 1 storm would bring about 1 to 2 feet of current rises, and a Category 2 would bring about 2 feet,” Ricks explained.

They are still developing scenarios for larger storms.

Chris Franklin, meteorologist at WVUE, said having a hurricane right now is something to think about, but the odds of it are unlikely.

The numbers seem to agree with him, according to hurricane statistics. Since 1900 the U.S. has been impacted by only 11 hurricanes formed in June. A hurricane coming before river levels go down is a mere 6.5 percent.

But with the chances of higher water, lake and river tidal surges and wind action, uncertainty about the up-coming storm season still remains.