In 2011, when Hurricane Irene hit New York, it prompted city officials to ask Dutch expert Jeroen Aerts for advice on flood protection. Halfway through Aerts's study, Sandy hit. Its tropical-storm force winds extended 1,000 miles, stirring the storm surge that caused much of the $37 billion in damage to New Jersey and $19 billion in destruction to New York. The storm demonstrated how much more prep-aration was needed—and also why New York placed third (behind Tokyo and Miami) of major coastal cities in a recent ranking of flood vulnerability.
Mayor Michael Bloomberg's new $20 billion storm-protection plan offers more than 250 initiatives to reduce risks, including ideas suggested by Aerts. (Not all the Dutch wisdom was heeded—see below.) Aerts deems the Bloomberg plan "good." But asked to name what's most needed for a strong flood-defense system, he doesn't choose seawalls or even money. "Courage," he says.
- Widening and elevating beaches in Queens and Staten Island to create buffers
- Creating dunes and augmenting them with plantings to prevent erosion
- Building closable storm-surge barriers to protect urban canals
- Protecting key infrastructure, such as power and gas grids, subways, sewers
- Repairing and/or raising waterside bulkheads
- Tweaking zoning codes to encourage elevation of equipment such as fuel tanks and telecom cables
- Nourishing wetlands and reefs along city shores
- Large surge barriers akin to those that protect the Dutch coast. They're undeniably expensive. But Aerts says they are still the most cost-effective measure. "Why not look at the pros and cons?" he asks.
- Regional coordination with New Jersey and Connecticut. "This is really strange," Aerts says. Storms cross state boundaries; so do commuters, infrastructure, and businesses. Coordination is a must.
A version of this article appeared in the November 2013 issue of Fast Company magazine.