Katrina is believed to have killed more than 1,200 people in New Orleans and the adjoining parishes. Four-fifths of the city was flooded, with some parts under more than six meters of water. The area suffered an estimated US$28 billion in direct damage to its housing and other infrastructure.

Yet what felled New Orleans was not the windstorm that pummeled much of the Gulf coast, but the failure of the city’s flood protection infrastructure to perform as designed. New Orleans’ levees (embankments) failed because they were poorly designed and built, and because the Mississippi Delta is sinking as a result of these levees, which block sediment from returning to build up beaches and barrier islands. While many factors besides levees and dams – not least of which is global warming – are contributing to increasing the severity and frequency of floods worldwide, it is indisputable that the proponents of flood control have failed to deliver on their expensive promise of reducing flood damage.

During the construction of the Vaiont Dam in the Italian Alps, various surveys showed that the chosen site was geologically unstable, especially the peak called Monte Toc, which rose next to the future reservoir. The construction company SADE, which would also own the dam, covered up the findings. They also ignored warning signs such as deep cracks on the side of Monte Toc that appeared when the reservoir started to fill. Villagers nearby requested evacuation after the cracks appeared, but were ignored.

On 9 October 1963, approximately 270 million cubic meters of rock from the side of Monte Toc collapsed into the reservoir, generating a gigantic wave that overtopped the dam and completely destroyed Longarone and five nearby villages. A second wave hit the towns of Erto and Casso. Almost 2,000 people were killed. Only one of SADE’s directors was sent to prison, for just over a year.