![Complexity of urban flood protection systems in terms of cost, total population and value of property protected, and infrastructure investment.](https://levees.org/wp-content/uploads/2016/08/Graphic-Flood-Systems-v5-300x163.jpg)
Complexity of urban flood protection systems in terms of cost, total population and value of property protected, and infrastructure investment.
The Greater New Orleans urban flood protection system has no peer. On a scale of one to ten, if the GNO system were a ten, the next closest – Cape Girardeau, Missouri – would be a three.
And appropriately, for a system of this scope, each project in the $14.5 billion GNO system has – or soon will have – a highly detailed Operation and Maintenance, Repair Replacement and Rehabilitation Manual (OMRR&R).
The Army Corps of Engineers writes the guidelines. The local levee districts and the state Coastal Protection and Restoration Agency (CPRA) administer them. Nothing is left to chance for this, the most complex urban system in the nation in terms of cost, total population and value of property protected, and infrastructure investment.
Immediately after Hurricane Katrina, the corps rewrote the OMRR&R guidelines for inspections. Maintenance inspections are more uniform, more frequent and utilize modern technology. But the corps’ new inspections tools – more rigorous and frequent as they are – are still only visual.
Today, it is sometimes assumed that the new inspection protocols could have saved New Orleans. This may be rooted in the assumption that the Orleans Levee Board did not properly do its federally mandated maintenance. But, corps representatives testified before Congress that the OLD did an outstanding job with its maintenance activities. Indeed, certificates that the corps awarded to the OLD every year confirm this.
Bottom line, even today’s inspections may not have exposed the corps’ pre-Katrina design flaws deep underground.
Southeast Louisiana Flood Protection Authorities East (SLFPAE) created after Katrina is well aware that the corps’ visual-only inspections can pick up only the most obvious problems when it may be too late. So, SLFPAE is testing remote sensing methods of quickly imaging the inside of levees and the strata below using geophysical instruments towed behind an ATV.
SLFPAE has funded research with a company in California – Tremaine & Associates – that specializes in high-speed electrical resistivity surveying. This approach was first used to find buried archaeological sites, but is now being used in the Sacramento River delta to image the insides of levees and the strata beneath them.
Additionally, the Authority is beginning a program of monitoring subsidence rates to re-evaluate storm surge elevations and adjust the system proactively.
Technologies like these could provide a more complete snapshot that could be repeated to see problems earlier, as they develop.
After Katrina, the corps rewrote the guidelines for local levee maintenance, not just for New Orleans, but also for the entire country. The fifty-five percent of the American people living in counties protected by levees are now exposed to a reduced risk of flooding.
Also after Katrina, we discovered that the Greater New Orleans region needed a regional levee board staffed with experts that is better suited to this extremely large and unique system.
The pre-Katrina levee boards did not drown New Orleans. But going forward, the East Flood Authority – armed with its new self-developed technology, aggressive storm surge reanalysis and detailed measures of subsidence – will hopefully, provide insights and realistic risk reduction not available before.
Stephen Estopinal – Vice President of the Southeast Louisiana Flood Protection Authority East – contributed to this post. A version of this post appeared in the New Orleans Times-Picayune on August 3, 2016.
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