It was far from a nightmare scenario, but Francine could keep local officials up at night for a while.
That’s because the hurricane, a relatively weak system that dissipated quickly, exposed critical drainage flaws in New Orleans and Jefferson Parish that are sure to pose growing problems in the future. Rainfall associated with hurricanes is expected to worsen because of climate change, and the low-lying New Orleans area, dependent on an aging system of underground drainage lines and pumps, will struggle to avoid widespread flooding in more severe circumstances.
Experts point to storms like Hurricane Harvey, a Category 4 hurricane that stalled over the Houston area and caused disastrous flooding in 2017, as the sort of extreme rainfall risk the area could face. That storm dumped up to 60 inches of rain – far beyond what interior parish drainage systems could handle.
BY DAN SWENSON | Graphics Editor
Francine, by contrast, was a relatively fast-moving Category 2 storm, but its unique, amorphous structure led to higher rainfall totals than might have been expected. While the New Orleans area has a drastically improved levee system, built at a record cost of around $14.5 billion, it is designed to protect primarily against storm surge.
“If you think of us as a walled city, that in some ways makes it even more challenging to deal with the water that falls from the sky,” said Dana Eness, executive director of the Urban Conservancy and a member of the New Orleans Sewerage and Water Board’s Customer Advisory Committee.
Eness, who helps lead a small-scale effort to alleviate the city’s overburdened and outdated stormwater system, added: “There’s nothing that those levees do to keep stormwater from falling on us.”
‘No way around it’
Jefferson Parish in particular was reminded of the threat during Francine. Drainage canals overflowed and at least 100 homes flooded in Kenner when 7 to 9 inches of rain – and in some cases more than a foot – inundated the parish’s east bank.
Mechanical issues plagued some of the parish’s 194 pumps, but Parish President Cynthia Lee Sheng said that was not the cause of flooding. According to her, “we were just outpaced with the sheer amount and volume of water.”
Jefferson officials are well aware they can’t manage the increased rainfall with a traditional drainage system of canals and pumps alone. That’s why, in 2023, the parish adopted a plan to incorporate green infrastructure into public works projects and private development.
A Kenner resident cleans up after Hurricane Francine on Thursday morning, Sept. 12, 2024.
Mark Drewes, Jefferson Parish’s public works director, said the parish is always looking for ways to improve its drainage system, which spans nearly 340 miles of canals and 73 pump stations. He pointed to several ongoing projects to expand pumping capacity.
Under construction are two new pumping stations on either side of Veterans Memorial Boulevard near the Orleans Parish line. The parish is also in the design phase for new pumping stations in the Woodlake Estates subdivision in Kenner and on West Esplanade Avenue in Bucktown.
It has hired a consultant to update its master drainage plan, which should be completed next year and provide more advanced data on ways the parish can improve its drainage system, Drewes said.
In New Orleans, all five of its diesel generators went down when an auxiliary feeder failed during Francine, but, as was the case in Jefferson, the rain would have been impossible to deal with anyway, said Ghassan Korban, executive director of the New Orleans Sewerage and Water Board.
“That truly would have overwhelmed any system, anywhere,” said Korban. “Add the complexity of the mechanical system in this city, you will have challenges. There’s no way around it.”
The city’s drainage system is in notoriously poor shape, particularly the Sewerage and Water Board’s inability to power the pumps, and City Hall’s failure to maintain the city’s 72,000 catch basins.
After years of hand wringing, city leaders have finally set a course for fixing those problems in the near future. A $300 million power complex is currently under construction, and responsibility for catch basins should soon be transferred to the S&WB, with a mandate to conduct a regular maintenance schedule.
But those solutions don’t address a more fundamental issue: The city’s drainage system isn’t designed to handle 21st-century rainstorms, even when it’s in great shape.
‘Dumped buckets of rain’
Officials in both New Orleans and Jefferson Parish say their systems can drain one inch of rain in the first hour of a storm, and half an inch every hour thereafter.
In New Orleans, at least four storms in the last year, including Francine, have exceeded that threshold. The S&WB had power shortages or suffered failures during all of them.
While hurricanes also pack dangerous wind and storm surge, Francine’s rainfall wasn’t much different than recent storms that are typical of a tropical climate.
In April, for example, most parts of the city saw peak hourly rainfall totals of two to three inches from a storm that also caused citywide flooding. Total rainfall for that storm ranged from six to eight inches, with isolated areas seeing more. Those totals are almost identical to Francine.
Federal flood models suggest such storms are far from anomalies and that New Orleans should expect to see them with rain that intense on a yearly basis.
The intersection of Chappelle Street and Catina Street in Lakeview was taken over by flooding as Hurricane Francine tore through New Orleans on Sept. 11, 2024.
By JERRY DICOLO | Staff writer
While the effects of climate change on future hurricanes are still being studied, there is considerable consensus on warmer temperatures leading to growing rainfall with storms, said Paul Miller, a coastal meteorologist at LSU. He referred to a study polling an expert panel showing that concern with the highest level of consensus among a range of topics related to climate change and hurricanes.
The reason why that is expected to occur has to do with warmer air being capable of holding more moisture, he said.
“The rainfall associated with hurricanes is one of the things that there’s probably the most consensus or confidence about when we think about changes in hurricanes moving forward,” Miller said.
Miller pointed to Harvey as a scenario that could pose a huge risk — “a storm that made landfall and then kind of stalled out.”
“There was no real steering current to move Harvey away from Houston, and so it just dumped buckets of rain for days and days and days,” he said.
Miller also says a growing concern for south Louisiana involves “compound flooding,” or a combination of storm surge and extended, intense rainfall. Storm surge is moving in, but rainfall is trying to drain out, and “you sort of end up with a log jam,” he said.
‘Not solving our problem’
There are smaller projects attempting to address the issue in individual ways while also seeking to raise awareness, especially when it comes to New Orleans’ unique, bowl-shaped geography.
The Urban Conservancy’s “front yard initiative” encourages residents to create more green space on their properties so water-drinking soil can be the first line of defense instead of the city’s catch basins.
The program offers homeowners partial reimbursement up to $1250 – or $2.50 per square foot – to remove paving on their property. It has provided financial assistance to more than 150 homeowners to remove nearly 100,000 square feet of yard paving over the past nine years, said Eness.
A road is flooded in the University City neighborhood in Kenner after Hurricane Francine on Thursday morning, Sept. 12, 2024.
That translates into more than four million gallons of water kept out of the drainage system each year, she said.
The conservancy has also partnered with other green infrastructure organizations to provide free installations for residents in flood-prone Hoffman Triangle if they can’t afford the partial reimbursement.
It’s part of a broader effort to reevaluate south Louisiana’s stormwater management strategy in a way that mimics nature. Some of the city’s pipes are a century old, Eness explained, and “they can only take so much stress” in a city that is also sinking.
“If all we were to do was just to push the rainwater out of the streets as fast as we could and into the lake, we’re still not solving our problem because by doing that we’re also contributing to subsidence,” she said.
Staff writers Jeff Adelson and Mark Schleifstein contributed to this story.
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Publish date : 2024-09-14 22:00:00
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