The Outer Banks are Dynamic Barrier Islands - Hurricane Dorian May Accelerate the Normal Cycle
Disclaimer: I am NOT a scientist.
Anyway - when I was there last month I visited Cape Hatteras National Seashore where there was plenty to learn about the islands constantly changing in shape, size, shorelines, and natural communities. They even had to move a lighthouse not too long ago due to the shifting islands.In regard to Dorian, Tallahassee experienced no hurricane, the Bahamas were obliterated, and as I began to write this a week ago, they were airlifting OBX residents out due to flooding.
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USA Today - Hurricane Dorian still 'raging' as airlifts begin in Outer Banks. Storm moving out to sea"The storm's powerful winds knocked out power at 215,000 homes and businesses across the state as massive storm surge threatened buildings along the coast.
"Flooding on the Outer Banks had some residents seeking refuge in their attics. Hundreds were feared trapped by high water, and neighbors used boats to rescue one another.
"Officials announced plans Friday afternoon to airlift residents off Ocracoke Island to a shelter further inland, according to a press release. The county said it would commence evacuations of the island by ferry as soon as possible."
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Once I arrived, I went to the National Seashore visitor center. Here's a better picture to view the island map.
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The Cape Hatteras Island Museum goes into detail about the lighthouse move, among other interesting tidbits. I apologize for the terrible pictures, I was rushed. They were blurry and NPS exhibit spotlights can be difficult. Heavy editing to try to get some sort of clarity.
'Why?' should always be the first question. In 1870 the Cape Hatteras Lighthouse was built about 1,500 ft from the shoreline. The foundation was great, but the island area around it kept moving because barrier islands are extremely dynamic landforms. Wind and water carry sand from east to west across the island. By the mid 1990s, the lighthouse went from 1,500 ft from the shoreline to only 150. The NPS didn't want to just lose a national historic landmark, so they relocated the whole entire station operations in 1999. The lighthouse is now 2,900 feet southwest of the original location. Then they had to get ready by digging, sawing the lighthouse from the foundation, and other stuff you can read in the photo below on the right.
Below is a roller that was one of 100 that were used to move the lighthouse and its platform along the steel travel beams. They remind me of those god awful roller slides at places like Discovery Zone and FunScape.
The journey lasted 23 days and was complete on July 9, 1999. This doesn't mean challenges are over. They are, but just for the present. Big storms, in addition to the natural sand migration will keep carrying sand from the oceanside to the soundside. At least they know how to move it for the next time.
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The above information provides a general understanding of how the barrier islands change and how much it can affect. The angle of the info changed when I immersed myself in the wilderness on the Buxton Woods Trail. I'll have another post later with more info about the cool nature stuff I saw on the hike, since this one is focused more on the barrier islands.
There are informative sign posts along the trail as most nature trails have. They focus on the factors responsible for the formation and character of the largest forest on the Outer Banks. Get your hiking shoes on and join in. Buxton Woods is surrounded by water and about 30 miles from the mainland. Water warms and cools slower than land, buffering extreme temps. There are very few below freezing days, and it is a rare occasion for the temps to rise above 90 degrees. The exact origin of the islands is unknown. The sign says that "an overwash/migration theory combined with spit extension seems most acceptable." I'm not a scientist, so the explanation is just over there ------------------>>>> Dunes - 'an asylum for island vegetation'. The trail goes along sandhills that were once dunes adjacent to the beach. Newly formed dunes offer a protective shield for the old dunes allowing plants with less salt tolerance to colonize the old dunes. On the trail there is saw palmetto and yaupon, but it used to be covered in seagrasses that could hold the sand deposits together and prevent it from blowing or washing away. The root systems become the backbone of sand dunes.
Land growth was a big factor allowing the woods to grow. As the salt spray is farther away, larger trees start growing among the shrubs, eventually shading them out. A wide island is more stable and has enough protection to allow a small maritime forest community to develop despite harsh coastal conditions. Once the community reaches maturity, live oaks dominate. Loblolly pines are present where there is even less salt. The soil is another challenge. It is infertile and made largely of quartz sand where there is little nitrogen and other necessary nutrients.
Since the islands are dynamic, there are also temporary features that can occur. Sedges are a great example. They are freshwater ponds/marshes that form between old beach ridges that dip below the water table.
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After getting dirty in the marsh, I went to the beach access area where the lighthouse used to stand. First you see an image of the sign with where I was standing and the old location. Then I have two more pictures from that same location - one of the open beach area and then looking to my right at the lighthouse in its current location.
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Barrier islands change more rapidly than most landforms in normal conditions. Events such as hurricanes (and potentially Dorian) can accelerate the process. Is it a bad thing? My amateur understanding is no. It causes inconveniences, like having to relocate an entire lighthouse, but the project ended up being awarded an outstanding civil engineering achievement. Also change is a good thing if you're willing to put in the effort to adapt.
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