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.
[Image: Flickr user David Shankbone]