. Coast watch. Marine resources; Oceanography; Coastal zone management; Coastal ecology. Photo by Steve Murray. Sandbag groins are used to reclaim lost beachfront worth of erosion overnight. And, although much of the sand lost during storms returns, gradually, with calmer weather, that is no consolation to someone whose house collapsed after a storm tide swept the land right out from under it. "One of the troubles with predicting erosion rates is that we really do have no idea how to predict what the short- term erosion is going to be like during a major storm," Riggs says. "In
. Coast watch. Marine resources; Oceanography; Coastal zone management; Coastal ecology. Photo by Steve Murray. Sandbag groins are used to reclaim lost beachfront worth of erosion overnight. And, although much of the sand lost during storms returns, gradually, with calmer weather, that is no consolation to someone whose house collapsed after a storm tide swept the land right out from under it. "One of the troubles with predicting erosion rates is that we really do have no idea how to predict what the short- term erosion is going to be like during a major storm," Riggs says. "In a major hurricane, the barrier island itself be- comes the surf zone, with twenty-foot waves crashing against the buildings. You can't design anything to with- stand ; There are never very many people or machines around logging data and tak- ing notes during a major hurricane. And, the exact interaction of waves, wind, sand and buildings is still un- known. Also, the mathematical models available for predicting short-term ero- sion do not take into account all of the variables. John Fisher and Margery Overton, two North Carolina State University (NCSU) civil engineers, are doing Sea Grant research into one of those variables—the role of dunes in short- term storm erosion. They say that predictive models have been based on the assumption that a storm would take as much sand from the dunes as it needed to offset the increased wave energy and reassert what has been called a "dynamic ; "The old model depends on looking at the beach profile if an extreme storm took the beach to an equilibri- um, on the assumption that beaches tend to erode to a stable profile, a geometric shape," Fisher says. And Overton continues: "In the case that you have a shorter-term storm, a model like that is not going to be ap- propriate, because the beach won't have had time to reach that ; Fisher and Overton are using a wave tank to simulate dune
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