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Hurricane Sandy did more harm last year to coastal cities and homes than any hurricane in U.S. history except for Katrina. Most of that damage has been repaired. Hurricanes can also wreak havoc under the water to the part of the coastline known as the shore face. But as NPR's Christopher Joyce reports, new research suggest the shore face in at least one area of Long Island fared well in Sandy.
CHRISTOPHER JOYCE, BYLINE: When Hurricane Sandy hit Long Island, it pounded the shore face. That's the Sandy underwater slope that runs up to the shore. The shape of a shore face influences how fast and high water moves on to land. Sandy pushed water up the shore face and on the towns and bays. When it retreated, it sucked all sorts of urban junk back out to see. Last January, just months after the storm, NPR joined a crew of scientists on an ice-bedecked research boat to survey the damage to the shore. Beth Christensen from Adelphi University showed me a map of what got flooded.
BETH CHRISTENSEN: This is a power plant. Here's a sewage treatment plant, here's another sewage treatment plant, another sewage treatment plant. Here's a runoff coming in from the streets through all of those creeks. And so, all of that combined ends up in these sediments.
JOYCE: Onboard that cold day was John Goff from the University of Texas at Austin. He was there to scan the seafloor with radar. In addition to finding polluted sediments, he wanted to see if parts of the shore face had been washed away. That shore face protects the land from erosion by ocean waves.
JOHN GOFF: We're going to expect more storms in the future. And so understanding the impact of these storms is really important.
JOYCE: The group bills itself as a rapid response team. Ocean scientists swoop in after storms to study the damage they do to shorelines. After Hurricane Ike in Texas in 2008, Goff found that the storm surge had actually remodeled the shore face, moving huge amounts of sand out to sea. Not so with Sandy.
GOFF: Well, what we found was quite different. And, yes, it did surprise us.
JOYCE: The seafloor off Long Island that Goff discovered has rows of sand ridges, underwater sand dunes 10 feet high or so that run parallel to shore for up to a half a mile.
GOFF: I think of these ridges as kind of cushioning the blow. After the hurricane, they are still there. We didn't really see any massive destructive erosion of the shore face.
JOYCE: Goff says many coastal areas along the eastern and southern U.S. have these underwater sand ridges. That's going to be important because the sea level is rising. Over time, higher sea levels will eat away at the coastline, undercutting anything that's built there. And during storms, higher sea levels mean it's more likely that wind and waves will push water higher up onto land.
But Goff says these sand ridges seem to slow down erosion and perhaps prevent flooding. That's hopeful news for coastal cities facing sea level rise. The news on pollution isn't so good. There were toxic chemicals and metals in the mud at the bottom of estuaries and bays along Long Island. Sandy sucked a lot of that back out to the ocean where it got spread around.
The team will continue to track that. The team discussed their findings today at a meeting of the American Geophysical Union in San Francisco. Christopher Joyce, NPR News.