sand and maybe even the grain size 

 of the sand that influence how long 

 a sand dune will hold the ocean back, 

 says Sea Grant researcher John Fisher. 



Fisher and Margery Overton, two 

 civil engineers at North Carolina 

 State University, are studying the 

 relationship between storm waves 

 and dune erosion as part of a Sea 

 Grant project. 



The duo have experimented with 

 simulation dunes at the U.S. Army 

 Corps of Engineers Research Facility 

 at Duck and in the Oregon State 

 University wave tank. 



Fisher and Overton learned that 

 the height and frequency of the 

 waves and the duration of a storm af- 

 fect how fast a dune erodes. 



"Now, I know those seem like ob- 

 vious factors that you don't need a 

 study to determine, but it's really 

 more complicated than that," Fisher 

 says. 



By feeding dune and storm mea- 

 surements into a mathematical model 

 that Fisher and Overton are develop- 

 ing, they may soon be able to predict 

 dune erosion for a given set of storm 

 conditions. 



And that's valuable. 



Resource managers could predict 

 which storms are likely to cause ero- 

 sion and pinpoint areas that would 

 be hardest hit. And the information 

 could help property owners rebuild 

 or reshape their dunes for better 

 durability in the future. 



If you're planning to build a dune, 

 be it with sand fences or vegetation, 

 Rogers has some tips. 



Always build your dune well be- 

 hind the line of vegetation. And, he 

 says, if you have a deep lot, it's better 

 to build your dune either under- 

 neath or immediately in front of your 

 house as far away as possible from 

 the beach. 



Don't build your dune at the edge 

 of the beach or build your house on 

 or just behind a pre-existing beach- 

 front dune if possible, Rogers warns. 

 Dunes just off the beach are the first 

 ones gnawed away by storm surf and 

 surge. 



"Just remember to put as much 

 sand as possible between you and 

 the ocean," Rogers says. 



And before building any dune, 

 check with your local Coastal Area 

 Management Act permit officer. 

 There are some specific regulations 

 regarding dune building, especially 

 with bulldozers. And other CAMA 

 regulations govern how far behind 

 the dune or first line of vegetation a 

 house should be sited. 



Above all, Rogers advises not to 

 build a dune with a bulldozer or 

 front-end loader. 



"They're ineffective," he says. 

 "They make property owners feel 

 better, but they provide little or no 

 actual protection because of where 

 they're placed." 



Bulldozed dunes are made of sand 



just pushed off the beach and placed 

 well in front of the first line of the 

 vegetation. They're too close to the 

 ocean to provide any defense. 



Besides, you can't just push a pile 

 of sand in front of your house and 

 expect it to stay there. Dunes need 

 vegetation to hold them in place. 



Sea Grant researchers Stephen 

 Broome, Ernest Seneca and W.W. 

 Woodhouse pioneered dune stabili- 

 zation research in North Carolina 15 

 years ago. 



Broome and Woodhouse, soil sci- 

 entists, and Seneca, a botanist, 

 learned that the roots and rhizomes 

 of dune grasses and sea oats provide 

 a skeleton for the dune that holds it 

 stable. And the heads and stems of 

 the vegetation trap wind-blown sand 

 to gradually enlarge the dune. 



Vegetation is extremely important 

 to any dune system. That's why when 



