Tracking Coastal Erosion From Storms

New data from sensitive airborne altimetry combined with undersea sensors is giving scientists better insight into how major storms can rapidly reshape coastlines. Reporter Sid Perkins discusses his Science News article on the scouring power of major storms.

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IRA FLATOW, host:

This is SCIENCE FRIDAY from NPR. I'm Ira Flatow.

A little bit later in the hour, it's National Prostate Cancer Awareness Month, and we'll be discussing prostate cancer screening and treatments.

But first, last weekend brought Hurricane Earl moving up the East Coast, and while there's little in the way of damage this time, as Earl remained out at sea, a powerful hurricane can cause the same amount of erosion to a shoreline literally overnight as a year's worth of regular wave activity.

Here to fill us in on the details is Sid Perkins. His story on the topic is in Science News. You can read more about the issue and other stories in Science News by going to sciencenews.org. Welcome back to the program, Sid.

Mr. SID PERKINS (Writer, Science News): Great to be with you, Ira, thanks.

FLATOW: Are we in the season now of erosion?

Mr. PERKINS: I think you are coming into the height of hurricane season. If I'm not mistaken, the upcoming couple of weeks is the most active part of the season on average. So they - if you've got one strike in land, you can certainly get large bits of erosion.

FLATOW: And how bad - how big an effect can a storm have?

Mr. PERKINS: Thinking back to Hurricane Ike, which struck Houston - or not Houston but Galveston two years ago next week, the ground zero for there was the Bolivar Peninsula, which normally in the course of a year gets about 1.4 meters of erosion, you know, chewing inland each year.

Hurricane Ike overnight essentially chewed inland about 50 meters, so 30 times normal, you know, 30 years' worth of erosion in a night.

FLATOW: Wow. And how does the way the storm actually hits the surface, how does that affect the erosion?

Mr. PERKINS: Well, again this came onshore right between - or just to the northeast of Galveston Island, and between Galveston Island and Bolivar Peninsula there. The onshore winds, the rotation of the storm, the winds over the Bolivar Peninsula were onshore. So that's where you got the surge, and that's where you got a lot of waves coming in on the top of the water.

To the southwest, you know, to Galveston and further down coast, the winds were actually blowing offshore because of the way the, again the rotation of this storm. So there, the water was actually being pushed offshore. You didn't have nearly as much erosion to Galveston and further southeast, or excuse me, southwest as you did on Bolivar Peninsula and to the northeast.

FLATOW: So one side of the storm gets onshore winds, one gets offshore, and so the water flows differently.

Mr. PERKINS: There is a difference there, yes. And when you get wave action on top of the storm surge that's being blown onshore, that's where you can really get some damage, which is of course what happened there on the Bolivar Peninsula.

FLATOW: And Katrina, was that a special case? Was that why it was so devastating there?

Mr. PERKINS: Well, one of the interesting things with Hurricane Katrina is that the storm hit to the east of New Orleans, which means that the strongest winds and the onshore winds were over on the Mississippi side. They got quite a bit of damage.

But what was really odd about the New Orleans situation is you were getting offshore winds, but to the north of New Orleans, you had Lake Pontchartrain. So you had a very large body of water there that was actually blown into New Orleans by the, what would normally be offshore winds.

FLATOW: Why are we learning more about hurricanes, Katrina and onshore wind storms right about this time now?

Mr. PERKINS: Well, I mean, there's a big confluence of technologies that people are using. They're using these small aircraft that can fly up and down the coast with laser altimeters on them. They'll fly up and down the coast two or three days before the hurricane comes and, you know, measure the dunes, measure the terrain, measure the buildings and houses, very high-resolution data.

And then, you know, two or three days after the storm, they can fly up and down the same coast. You can cover an area from New York to Boston in, you know, a 300-meter-wide swath of terrain in a single flight. So you can really get high-resolution comparisons before and after of what the effects of a storm is even in remote locations.

And people are also using things like innovative techniques like GPS equipment mounted on all-terrain vehicles. You can ride up and down the water's edge and essentially map the coastline, you know, over a fair distance in the course of an afternoon.

So people are just collecting a lot more data, which allows you to get better statistics and, you know, construct better models of what coastal erosion can happen.

FLATOW: Sid, is there any tool that they would like to have, or is there a perfect kind of thing, a technical device or something that they don't have that would make their job a lot easier? I mean, can you think of some, you know, kind of technology, whether it's in a satellite looking down or stuff on the ground or in the water?

Mr. PERKINS: Well, I mean, this use of laser altimeters is really interesting now. They are, again, mapping areas that normally would take, you know, an army of surveyors and a horde of grad students...

(Soundbite of laughter)

Mr. PERKINS: ...to collect all this data and then, you know, just in the course of a couple of flights, you can take all this data, and there's - you know, in a sense, you could argue there's more data than you know what to do with.

But it's a great repository of stuff that you can go back, and you can look at those long-term patterns over time and also the direct before and after comparisons. It's just something that they haven't really had in the past.

FLATOW: Well, Sid, thank you for taking time to be with us today.

Mr. PERKINS: Sure, thank you, Ira.

FLATOW: Have a good weekend.

Mr. PERKINS: Yep.

FLATOW: Sid Perkins, he's a science writer, and his story on storm erosion is in Science News, and you can read it and other science stories by going to sciencenews.org.

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