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An article published by the E&E News (April 11, 2019; picked up by the Scientific American Newsletter) caught my attention. It is about the sinking and possible redundancy (in about 4-years time) of the recently upgraded $14 Billion levees of New Orleans.
The massive upgrading was undertaken by the US Army Corps of Engineers (USACE) after the devastating 2005 Hurricane Katrina. It is rather well-known that the Mississippi River delta is facing higher than average sea level rise (some 9 to 12 mm per year) due to the combined effects of global sea level rise and deltaic subsidence.
The article has argued that the actual sea level rise (ASLR) in New Orleans area is occurring at a rate faster than anticipated. Although it is not clear whether the sinking is overall, or in some pocket areas of the levee, it raises some questions about the planning vision on part of USACE (being redundant in such a short period is not something anyone or any entity expects). And how much additional sinking the levee itself is causing on the ASLR?
Perhaps it teaches us a lesson about the limits of predictability (such as ASLR) and the consequent planning process. I invite all to reflect and react.
The purpose of this post was to raise awareness among the members of civil engineering communities – of a problem as important and massive as the New Orleans flood/storm surge protection levee. Indeed, the problem is more complicated than what one could discuss in this forum – not knowing what the actual conditions are. But a major undertaking – becoming ineffective (or less effective on the premise of designed scenarios) in about 4-years time after completion – is not something anyone can swallow easily. Of course, only a test – perhaps the likeness of Hurricane Katrina – can prove or disprove whether or not the assertion is true – but then it would be too late.
Thank you, Bill for pointing out my use of redundancy. I meant ineffectiveness, which is more aligned with Oxford English, but the Webster English and engineering define it as an extra layer of safety exceeding what is necessary. Yes, one should be careful in wording – because linguistic, cultural and technical connotations may not always agree.