Wednesday, June 13, 2007

Unlevel protection

The American Society of Civil Engineers released a very readable analysis of the Hurricane Katrina catastrophe last week. Maitri, a blogger and scientist with a curious mind, first made note of it on her blog. (The Times-Picayune finally noticed it Tuesday.)

The report is wide-ranging, and no doubt everyone who reads it will find something of passionate importance. Mine is this: level of protection.

As I have complained for months, greater New Orleans is doomed to flood again and again because of the very low level of protection. Congress and the president have deemed our fair city worthy of only a 100-year level of protection, a standard so low that commercial insurance writers are all but totally abandoning the area. We are rapidly approaching the point at which only government-backed insurance programs will be willing to take such risks.

ASCE notices this, too.

ASCE compared the level of protection we get with the level of protection afforded to Americans who live and work in the shadow of dams. They point out that dams are not designed merely based on frequency and availability of flood insurance--they are designed for LIFE SAFETY.

Let me say that again for the speed-readers and those of you in the back: THEY ARE DESIGNED FOR LIFE SAFETY.

ASCE points out that the federal Bureau of Reclamation's guidelines for public protection consider both the probable frequency of a catastrophic event and the likely loss of life. Simply stated, events that are both frequent and result in large losses of life are unacceptable.

Here's ASCE's example of unacceptable: "the historical performance of the hurricane protection system: a catastrophic failure, resulting in approximately 1,000 fatalities, which occurred once in 40 years of operation."

Applying the methodology for dam safety to hurricane levees, ASCE concludes:

"...if the hurricane protection system had been treated as a major dam, it would have needed to be designed so that the likelihood of failure would occur roughly once in 100,000 years to once in 1,000,000 years of operation."

Something to ponder as we await the release of the IPET Risk and Reliability Report.


mominem said...

Thanks for the Link. The report is the most readable and understandable report I've seen.

Mr. Clio said...

Tim, thanks for posting this. I'm going to share it with anybody I can find.

mominem said...


I have wondered why we can't establish within New Orleans a very few Base Flood Elevations. I've worked at trying to understand the existing flood zones and a few make sense.

Being only an Architect why can't we establish a Base Flood Elevation for each levee protected area in New Orleans.