By 2010 New Orleans will (probably) be flooded only once every 100 years. The NL. has a system designed to protect populated areas against anything but a 1-in-10,000-years flood.

Every July the country’s leading disaster scientists and emergency planners gather in Boulder, Colo., for an invitation-only workshop. Picture 440 people obsessed with the tragic and the safe, people who get excited about earthquake “shake maps” and righteous about flood insurance. It’s a spirited but wonky crowd that is…