Timing is everything: How vulnerable to flooding is New York City?

A report just released in the most recent issue of the Bulletin of the American Meteorological Society offers hope that a new high-resolution storm surge modeling system developed by scientists at Stony Brook University will better be able to predict flood levels and when flooding will occur in the New York metropolitan area, information crucial to emergency managers when planning for impending storms. The report also warns that flooding is dependent not just upon the intensity of the tropical storm, hurricane, or nor’easter, but also on the local phase of the tide at the time of the storm.

Model simulations showed that if Tropical Storm Floyd had arrived in NYC a week earlier, coinciding with a spring (fortnightly) high tide, water levels would likely have been high enough for minor flooding to occur. Another simulation, which used wind levels of a Category 1 hurricane timed to arrive at spring high tide, predicted water levels likely to have caused significant flooding. These results suggest that the New York City metropolitan region was spared from flooding during Tropical Storm Floyd only because the storm’s winds had weakened before reaching the region and because the strongest winds luckily occurred during local low tide.

“We’re playing Russian roulette in some sense with these storms coming up the coast,” says Colle. “If we have a high tide or spring high tide when we have one of these events, then we’re in trouble.”

If a category-3 hurricane hit NYC, the U.S. Army Corps of Engineers estimates that nearly 30% of the south side of Manhattan would be flooded. Storm surge flooding could threaten billions of dollars of property and have a grave impact on the lives of the millions of people who live in NYC.

EurekAlert