bulkheads, and jetties, are not allowed. 



Renourishment is a method of 

 trucking or pumping compatible sedi- 

 ments from another source, usually from 

 state or federal navigational dredge 

 projects, onto the eroded beach. Bulldoz- 

 ing is the process of redistributing sand to 

 provide temporary protection to existing 

 dunes and beachfront structures. It does 

 not add new sediment to the beach from 

 outside sources. Each method comes with 

 a set of environmental criteria. 



For many years, coastal communities 

 have relied on the U.S. Army Corps of 

 Engineers (ACOE) to design and 

 implement beach replenishment pro- 

 grams. Projects must meet environmental 

 impact tests set by CAM A and the federal 

 government, says Tom Jarrett, engineer 

 for the corps' Wilmington district. "The 

 biggest factor for a successful project is 

 the distance we can move the beach 

 seaward, and are able to maintain the 

 distance," he says. A deep, sandy strand 

 absorbs wave energy, while dunes 

 provide a line of defense against advanc- 

 ing wave action. 



The pricetag for renourishment 

 varies with the scope of the project and 

 proximity to the sediment source. 

 Federal, state and municipal sources 

 usually share costs. Most beach commu- 

 nities pay for beach rebuilding programs 

 with part of a hotel tax. These taxes are 

 levied by the local governments, but are 

 authorized by state legislators. 



Led by Oak Island Mayor Joan 

 Altman, the newly formed North 

 Carolina Shore and Beach Preservation 

 Association wants the state and federal 

 governments to consider a more perma- 

 nent revenue structure to support 

 renourishment projects. The group says 

 the focus should be on the economic 

 impact of beaches on their communities, 

 counties and the state. Beach residents 

 and tourists annually spend more than $8 

 million for each mile of beach, compared 

 to the $1 million per mile cost for 

 renourishment, the association asserts. 

 Coastal-related tourism pumped about $3 

 billion into the state economy in 1998, 

 according to the N.C. Department of 

 Commerce. 



Dynamic Systems 

 On the Move 



But, barrier islands are much more 

 than economic engines to North Carolina 

 Sea Grant researchers Charles Peterson 

 and John Wells. 



Peterson and Wells study the 

 physical and biological dynamics of 

 barrier islands at the University of North 

 Carolina at Chapel Hill's Institute of 

 Marine Sciences at Morehead City. In 

 their study, "Restless Ribbons of Sand," 

 the scientists explain that coastal barrier 

 islands hug 2,700 miles of our nation's 

 shorelines from Maine to south Texas. 



The barriers absorb ocean energies 

 and provide the mainland with a "line of 

 defense against wind and tidal energies 

 and especially against the ravages of 

 frequent winter storms and occasional 

 hurricanes." 



To understand what is happening to 

 the barrier islands, Wells and Peterson say 

 it's necessary to understand something 

 about their formation. Geologists theorize 

 that coastal barriers formed as sea level 

 began to rise about 1 8,000 years ago. 

 Coastlines retreated and ridges of beach 

 dunes were breached by rising water, 

 flooding the lowlands between ridges. 

 These ridges became barrier islands. 

 About 5,000 years ago sea level rise 

 slowed, as the islands migrated slowly to 

 their present positions. Global warming 

 could accelerate sea level rise, they say. 



But sea level change is only one 

 factor in the erosion equation. Barrier 

 islands, they say, are part of a "sand- 

 sharing" system. Waves strip away sand 

 from the upper beach and dunes, moving 

 it to the lower beach, or to the continental 

 shelf. In time, waves may push the sand 

 from offshore storage back to the beach 

 and rebuild the dunes. 



Sand also can be carried along their 

 beaches. This littoral drift can transport as 

 much as one million cubic yards each 

 year along dynamic barriers such as Cape 



18 EARLY SUMMER 2000 



