Important Message about LEARN NC

LEARN NC is evaluating its role in the current online education environment as it relates directly to the mission of UNC-Chapel Hill School of Education (UNC-CH SOE). We plan to look at our ability to facilitate the transmission of the best research coming out of UNC-CH SOE and other campus partners to support classroom teachers across North Carolina. We will begin by evaluating our existing faculty and student involvement with various NC public schools to determine what might be useful to share with you.

Don’t worry! The lesson plans, articles, and textbooks you use and love aren’t going away. They are simply being moved into the new LEARN NC Digital Archive. While we are moving away from a focus on publishing, we know it’s important that educators have access to these kinds of resources. These resources will be preserved on our website for the foreseeable future. That said, we’re directing our resources into our newest efforts, so we won’t be adding to the archive or updating its contents. This means that as the North Carolina Standard Course of Study changes in the future, we won’t be re-aligning resources. Our full-text and tag searches should make it possible for you to find exactly what you need, regardless of standards alignment.

Groins at Cape Hatteras

Figure 19. These groins trap sand near the lighthouse but encourage erosion elsewhere. (Photograph by Blair Tormey. More about the photograph)

When the lighthouse was threatened by erosion in the early 1960s, the federal government responded with a series of efforts to stem the shoreline’s retreat. In 1966, the National Park Service undertook a $300,000 beach replenishment project that pumped sand from the tidal deltas of Buxton Inlet. But the sand was too fine-grained and quickly eroded again.

In 1969, the U.S. Navy subsidized the construction of three 500-foot groins to trap sand in front of the lighthouse. There are drawbacks to the construction of groins, though. Once a sediment trap is created in one location, the downstream beaches become sites of erosion, as the longshore current is able to carry more sediment after depositing its load upstream of the groin. Although the groins at Cape Hatteras were quite effective in trapping sand in front of the lighthouse, the erosion rate down drift of the groins increased by a factor of nine, which caused the beach south of the groins to retreat several hundred meters.

Figure 19 shows one of the groins at Cape Hatteras photographed in 1998. Notice how the groin is very effective in trapping sand on the upstream side (the left in this photograph) but produces pronounced erosion downstream (to the right). The erosion is marked by the lowered level of the beach surface, and the proximity of the shoreline on the southern side of the groin.