Interagency Study Concludes Structural Protection Can't Solve All Problems [REPORT]

imagesThe Interagency Performance Evaluation Task Force (IPET: a group organized by the U.S. Corps of Engineers in the wake of Hurricane Katrina) has released a draft of a report evaluating the performance of the New Orleans hurricane protection system during Hurricane Katrina and to assess the risks posed to the New Orleans region by future tropical storms. While certainly worth a look by those in New Orleans, the report is interesting for everybody working in other coastal areas for its conclusion that we can’t armor our way out of all coastal problems. In the words of the executive summary (PDF, written by the National Academies[NAS]):

“There are many inherent hydrologic vulnerabilities of living in the greater New Orleans metropolitan region, especially in areas below sea level. Post-Katrina repairs and strengthening have reduced some of these vulnerabilities. Nevertheless, because of the possibility of levee/floodwall overtopping—or more importantly, levee/floodwall failure—the risks of inundation and flooding never can be fully eliminated by protective structures no matter how large or sturdy those structures may be. . . .

The pre-Katrina footprint of the New Orleans HPS consisted of roughly 350 miles of protective structures including levees, I-walls, and T-walls. There was undue optimism about the ability of this extensive network of protective structures to provide reliable flood protection. Future construction of protective structures for the region should proceed with this point firmly in mind and in the context of a more comprehensive and resilient hurricane protection plan. . . .

Comprehensive flood planning and risk management for the New Orleans metro region will be based on a combination of structural and nonstructural measures, the latter including relocation options, floodproofing and elevation of structures, and evacuation studies and plans. Better risk communication also must be part of more effective mitigation and an improved state of preparedness. Structural measures such as levees and floodwalls should not be viewed as substitutes or replacements for nonstructural measures, but rather as complementary parts to a multi-tiered hurricane protection solution. “

Quite a shift from the old days when the solution was often to build a bigger seawall or levee. What do you think? Are they spot on? Missing the point? Let us know in the comments.

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