Hurricane Hugo, Storm-surge monitoring techniques, twenty-years later

The following podcast is a product of the U.S. Geological Survey and the South Carolina Water Science Center.

[Intro audio]: 1989 Hurricane Hugo audio mix: wind; stormy surf; news and evacuation monologue. Paul Conrads: "It's not a matter of if it's going to hit, it's when it's going to hit and you need to be prepared to be able to collect the necessary data to really help the resource managers protect the coast."

Ray Douglas: Major hurricanes produce walls of water called storm-surge that can reach heights of 20 feet above sea level. While the old method was accurate for measuring height of storm-surge, new methods provide a wealth of information on the timing, magnitude, and the nature of the storm.

Today on our program, Hurricane Hugo, storm-surge monitoring techniques twenty-years later. I am Ray Douglas, and you are listening to "Water Science for a changing world".

Paul Conrads is Surface Water Specialist for the U.S. Geological Survey in South Carolina. He and other hydrologists in the South Carolina Water Science Center measured the magnitude of the storm-surge along South Carolinas coast twenty-years ago. Paul thanks for joining us today. Describe for us, if you will, the USGS approach to data collection during Hugo.

Paul Conrads: Well for Hugo we knew the storm was coming so we were prepared to respond to the aftermath and that's what it was–it was a post event data collection effort. So we knew the storm hit the coast, it was a large storm so we went down to measure the high water marks of how high the storm actually got along the coast. It was a tremendous field effort, a large number of people involved, probably easily twenty people involved. Measuring marks from south of Charleston to Myrtle Beach. It's time consuming.  By the time we get the field notes in, reduce the field notes, put marks on maps so people can actually see just how high this water was, it's easily six months before we actually get this information disseminated to the public.

Ray Douglas: O.K. Well how would USGS handle the same event today?

Paul Conrads: Well today it's much more of a pre-event data collection effort where if a storm is threatening the South Carolina Coast and we have a projected track of that storm  we can go out and put out these pressure-transducers. These pressure-transducers record water-levels and they are about the size of a cigar. So we can take a number of these, say thirty, forty, fifty, whatever number, and we go down to the coast and we can attach these to structures that are in the path of the storm. So attach these to bridge structures, poles, whatever in the pathway. After the passing of the storm we can go down and retrieve the sensors and we can download the water-level data from the sensors. So in a matter of weeks now we can download the data and  previously it would take months to be able to produce that information.

Ray Douglas: O.K. Well the data is coming in faster, is it any better than the data that retrieved twenty-years ago?

Paul Conrads: Well you know twenty years ago what we measured was really just the magnitude of the storm-surge, of that wave as it comes on shore so we know how high it got. Now with these pressure-transducers that we set up before the storm it's actually recording the time of the storm coming on shore, so we not only have that magnitude but we have the timing as it comes on shore. So we know how high the water was and how long it was that high. Really the analogy for the difference really for Hugo is like taking a snapshot, it's like taking one little picture of the magnitude, where now it's like taking a filmstrip, an animation of the water coming in, that timing, height, and then the dissipation of the storm.

Ray Douglas: O.K. The Hurricane makes landfall, the data is in, where does it go from there, how is it used and who uses it?

Paul Conrads: For coastal management and planning, especially emergency preparedness along the coast they make a lot of use of the hurricane storm-surge inundation models. These models predict how high water will get and for how long along the coast. So information like this is critical for ground-truthing those models to make sure they are as accurate as they can be. The results from those models are really what are used for determining evacuation routes, for siting shelters during the storm, for identifying critical infrastructure that may need attention during a storm like nursing homes, hospitals, those sort of things. There's quite a bit of use for the data.

Ray Douglas: Paul thanks for all of the great work you and the USGS team do here in South Carolina. Any thoughts for the hurricane season for this year?

Paul Conrads: Well hurricane season is always a little anxious, but we realize with the number of people moving to the South Carolina coast that collecting this kind of information is really getting to be more and more important. We recently had a Category 4 storm pass along the coast and started realizing that it's not a question of if a storm is going to hit, it's a really a question of when a storm is going to hit.

[Close Audio]: 1989 Hurricane Hugo audio mix: wind; stormy surf; and hurricane aftermath news monologue.

Ray Douglas: HUGO, the modest Category 2 Hurricane that grew into a massive Category 4 and required immediate evacuations along the South Carolina coast. New USGS data collection techniques will capture larger amounts of data, to document, better understand, and predict storm-surge for the next hurricane that visits the South Carolina coast.

For more information on USGS activities in South Carolina, visit us on the web at sc.water.usgs.gov.

Water Science for a changing world is a product of the U.S. Geological Survey and the South Carolina Water Science Center.