Takeaways

Tropical storms are remembered for their “signature” impacts. Hurricane Andrew in 1992 will thus be forever remembered as a wind impact event for south Florida, and Hurricane Katrina in 2005 as overwhelmingly a water impact event. The water component comes in different forms, however: For the city of New Orleans, flooding from levee failure was the major Katrina impact, but it was storm surge that devastated parts of the U.S. Gulf Coast.

In the night of August 24, 1992, Hurricane Andrew made landfall as a Category 5 storm in the more agricultural southern zones of Miami-Dade County (a late wobble to the north would have impacted the urban Miami-Ft. Lauderdale area, likely tripling the losses). Nonetheless, Andrew killed 44 people (EM-DAT) and caused nearly $50 billion in losses (updated to 2016 dollars). Andrew, however, was a compact, relatively dry, and fast moving storm that never generated the usual killers in hurricanes (storm surge and flooding), but its fierce winds (reaching 165 mph sustained) hit “like a bomb,” and the recently (and hastily) built “planned unit developments” were particularly hard hit. Not surprisingly, nearly every mobile home along Andrew’s path was also destroyed.

Two post-Andrew scandals rapidly emerged in south Florida. The first was what The Final Report of the Dade County Grand Jury (August 4, 1993: 13) called a “keystone cops” response, where “No one was in charge. No one knew what to do. There was no plan.” The second scandal was the damage pattern, revealing poor design, poor construction, and lax enforcement of building codes. The combination led to substantial code, code enforcement, and response planning reforms at both local and State of Florida levels.

Thirteen years after Andrew, despite initially heading straight for New Orleans, Hurricane Katrina made a late northeasterly veer, and on August 29, 2005 as a Category 3 storm, the eye made landfall at Buras-Triumph, Louisiana on the west bank of the Mississippi River. Katrina’s previous Category 4 and 5 winds in the Gulf of Mexico, however, had built up a large envelope of water to the east, however, and the ensuing storm surge reached a record-setting 27.8 feet at Pass Christian, Mississippi, with only somewhat lesser heights elsewhere along the coast.

Despite the eerily accurate 2004 “Hurricane Pam” simulation, Louisiana in 2005 was much like the ill-prepared Florida in 1992. Most of the 1,833 Katrina fatalities (EM-DAT) were killed when the levees failed and flooded 80% of New Orleans, which Brinkley (2206:13) memorably described as “no more stable than a delicate saucer floating in a bowl of water. Any turbulence in the surrounding water is bound to flood the saucer.” In addition, the loss of coastal wetlands, which serve as shock absorbers for hurricane storm surges, due to development, oil and gas exploration, and the building of levees and canals exacerbated the risk.

In the end, Katrina caused nearly $125 billion in losses (updated to 2016 dollars), and more than 400,000 people were displaced – many never to return. The post-event assessments were brutal. A special report of the U.S. Senate Committee on Homeland Security (2006: 2) found four particularly damning failures:

1. Long-term warnings went unheeded and government officials neglected their duties to prepare for a forewarned catastrophe;
2. Government officials took insufficient actions or made poor decisions in the days immediately before and after landfall;
3. Systems on which officials relied on to support their response efforts failed; and
4. Government officials at all levels failed to provide effective leadership.

Viewing both events together rather than each singly, the prime takeaway is the need to fully comprehend the multi-component nature of hurricanes – wind, storm surge, and flooding. In that sense, Andrew taught only a partial lesson about the vulnerabilities of the built environment – the need to improve wind resistance. Katrina, however, brought home the storm surge and flooding problems that coastal and near-coastal development had created – exposures and vulnerabilities that were then massively reencountered in the New York-New Jersey coastal areas by storm surge from “Superstorm Sandy” in 2012.

References: (1) Brinkley, Douglas. The Great Deluge (New York NY, HarperCollins, 2006); (2)
Final Report Of The Dade County Grand Jury, Circuit Court Of The Eleventh Judicial Circuit of Florida In And For The County Of Dade, Fall Term A.D. 1992, Filed August 4, 1993 < https://www.miamisao.com/publications/grand_jury/1990s/gj1992f4.pdf > ; (3) Senate Committee on Homeland Security, Hurricane Katrina: A Nation Still Unprepared, Special Report of the Committee on Homeland Security and Governmental Affairs Together with Additional Views < https://www.gpo.gov/fdsys/pkg/CRPT-109srpt322/pdf/CRPT-109srpt322.pdf >

- Richard S. Olson, Ph.D.