OH CR4P!

Sometimes weather disasters go beyond the scope of what we could ever imagine or prepare for. Such was the case with the China floods in 1931, the Bhola Cyclone in 1970, and the more recent Indian Ocean Tsunami in 2004. But was it the same for Hurricane Katrina in 2006? Was New Orleans (its worst victim) completely at the mercy of such a huge storm, or could something more have been done to defend it?

The Storm

This past week marks the seventh anniversary of Hurricane Katrina's landfall, a deadly Atlantic hurricane that formed in 2005 and lasted from August 23 to August 30. This force of nature took 1,836 lives and, with $81 billion in damages, claimed its place as the most financially destructive natural disaster in history.

The storm first threatened the city of New Orleans while in the Gulf of Mexico on August 26. A voluntary evacuation was issued on August 27, and a mandatory evacuation was called a day later as the storm grew to a Category 5. New Orleans experienced intense winds, rain, and flooding over the next several days. The eye of the storm missed the city, but this fact meant very little to the many areas of the city which suffered catastrophic damages.

Perhaps the worst damage in New Orleans was done to the Lower Ninth Ward. Storm surge flood waters poured into this residential area from multiple places due to levee failures, and completely destroyed most of the houses. I remember visiting the Lower Ninth in the spring of 2009, nearly four years later, while helping with some ongoing restoration projects. Empty lots, a few restored buildings scattered about, and streets leading to nowhere were all that remained of the old neighborhood. Here are some photos I took:

Disaster Prevention: What/Who Went Wrong

Roughly 49% of the city of New Orleans has an elevation below sea level, not conducive for easy flood prevention. Since the flooding from Hurricane Betsy in 1965, the Flood Control Act of 1965 was put in place to initiate flood prevention strategies, including projects by the Army Corps of Engineers. The complete project plan for the city was projected to take about 13 years, but by the early 2000s was given a completion date of 2015 (40 years since its inception). In October 2002, Scientific America declared New Orleans was "a disaster waiting to happen".

A year after the storm, the Independent Levee Investigation Team released a report on the levee failures in New Orleans. According to their reports, while some flooding was inevitable due to the hurricane design levels authorized by Congress (Category 3 level), the catastrophic failure of major portions of these levees could have been prevented. Most of the fault was due to the incompleteness and inadequacy of portions of the outer levees. When these outer levees failed, waters surged through swamp areas intended to absorb what would have been normal overtopping, and passed easily over secondary levees not designed for such massive flows.

(Broken levee. Photo Credit: FEMA)

There were a number of reasons why these floodwalls and levees failed. For one, multiple sections were still well below design grade at the time of the storm due to the lack of funds provided to the Army Corps for the project. Other sections contained large portions of erodible and lightweight sands rather than hard and compact clays designed to resist water erosion. Many breaches also occurred at junctions between dissimilar sections and "complex" intersections; places where collaboration between multiple design teams is needed to do the job right.

In sum, the investigation team had this to say:

"The New Orleans regional flood protection system failed at many locations during Hurricane Katrina, and by many different modes and mechanisms. This unacceptable performance can in many cases be traced to engineering lapses, poor judgments, and efforts to reduce costs at the expense of system reliability. These, in turn, were to a large degree the result of more global underlying "organizational" and institutional problems associated with the governmental and local organizations jointly responsible for the design, construction, operation, and maintenance of the flood protection system, including provision of timely funding and other critical resources."

Sharing the Blame

Unfortunately, unacceptable performance was a nearly universal characteristic for those in leadership roles involving disaster prevention/relief in New Orleans. Most troubling was the evacuation "plans" for the city, which (although effective enough to evacuate 80% of the city's population) had no solution for the elderly, disabled, or others without means to leave on their own. As a last ditch solution, places such as the Louisiana Superdome were opened up to those who could not evacuate. But the problems that occurred there are another story…

References

Independent Levee Investigation Team Findings (pdf)

Hurricane Preparedness for New Orleans - Wikipedia