Seabrook profiles

For you newcomers to Seabrook, try to imagine what South Beach looked like in 1990 before the first nourishment. The accompanying profiles ("Seabrook profiles" icon at right) from Beach Court show the level of the beach before and after the 1990 nourishment project and this year's project.

In February 1990 (red line on graph) there was no beach and the Northern Channel was over 20 ft deep just a few feet from the seawall. Yikes!

The 1990 nourishment project saved the seawall by moving the northern channel (blue line on graph)

South Beach continued to erode between 1990 and 1995.

By 1996, erosion stopped and South Beach started to gain sand.

For the past decade, more sand has moved around Renken Point and accumulated on South Beach.

With a little help from sand scraping projects (2002, 2003, and 2005), the buildup of South Beach has forced the Northern Channel seaward.

The Northern Channel is now five feet shallower than it used to be -- and much less of a threat to Seabrook's Beach!

2004-2005 sand scraping Pan earthmovers loading sand from North Beach at low tide.

A bulldozer and farm tractor with scraper blade grading and dressing the beach.

Regrading and dressing slopes around Oystercatcher beach access. .

Scraped sand in place against the seawall around Beach Court on 30 December 2004 before project completion.

This past year gave South Carolina a taste of six hurricanes or tropical storms (out of 15 named storms). Alex nearly tore into the coast before turning with the Gulf Stream toward the Outer Banks. Bonnie on 12 August hit us coming through Georgia. Then Charlie came ashore near McClellanville with 85 mph winds. At the end of August, Gaston with ~55 mph winds came ashore in Georgetown County. Frances, after wiping out what was left of Florida's citrus crop, brought remnants across the upstate. Finally, Ivan's remnants brushed through upstate South Carolina after demolishing Alabama beaches.

Seabrook Island was literally surrounded with storm tracks this past season. Fortunately, the landfalls were north of the community or inland where only remnants of the storms remained. Nevertheless, there were impacts to Seabrook.

Whenever we have a series of nearby storms in quick succession, they generate larger waves than normal. Not the monstrous large seas of a direct hit, but waves that have a cumulative effect. Under Philip McKee's supervision, CSE resurveyed the beach in October and compared conditions with November 2003. Here is a synopsis of the results.

North Beach aerial photos 1986-2005

North Beach around Oystercatcher lost the equivalent of one dump truck load of sand for every foot of beach. That is a big turnabout from the buildup that we have seen every year since Captain Sams was relocated in 1996. Erosion north of Oystercatcher led to a small breach in the outer dune. While this was no immediate threat to homes, it was a concern because such breaches capture sand that would otherwise migrate down the beach. As soon as a contractor could mobilize, the breach was closed on Pearl Harbor Day by Goodson Construction Company.

Erosion of North Beach was offset by a healthy gain around Renken Point. (Near-miss hurricanes also produce the type of waves that can build up the beach in some areas.) The beach from Bonito Court to Beach Court widened by an average of about 30 feet (ft). Amberjack Court now has a dry beach at all tides. This is quite an improvement from 1989 when there was a channel 20 ft deep against the seawall at that location.

Renken Point accretion

The Beach Club area faired the worst during the past year, losing nearly two dump trucks' worth of sand per foot of shoreline. This left only a narrow wet beach at low tide. Our surveys show that the sand bar off the Beach Club also eroded. In 2003, the shoal was well exposed at low tide, but by October of 2004, little of it could be seen at any tide. We believe storm waves shaved off the top of the bar and allowed more wave energy to reach the Beach Club. The result was a loss of sand to North Edisto Inlet. While this set back recovery of South Beach by a year, we can be thankful that no severe damage occurred to the seawall or anyone's property.

In short, Seabrook's largely healthy beach had to absorb and adjust to many storms this past year. Whenever we see the shape of the beach change in a negative way in response to storms, we can usually expect to see a general rebound the following year. It may be hard to distinguish natural recovery from manmade changes though, because the POA just initiated another episode of scraping and nourishment along South Beach this winter. However, by springtime expect to see some new dunes forming and vegetation sprouting quickly along the sections that were impacted by the storms and bulldozers.

See you on the beach!

More Nourishment Using North Beach Sand

According to plan, in December the POA hired Goodson Construction Company (Darlington) to haul sand from North Beach to the area between Renken Point and the Beach Club. The first order of business was to close the breach in the foredune north of Oystercatcher. Then in mid December, the equipment got to work on South Beach.

Between December and February 4th, the Goodson's moved nearly 100,000 cubic yards. Scraped sand from the low tide beach was hauled around Renken Point then dumped and spread along the seawall near Beach Court.

CSE monitored the construction and resurveyed the beach immediately after the project. Check out the photos and charts.

Here are some things to look for between Renken Point and the Beach Club:

South Beach is about 150 ft wider and nearly 5 ft higher than last year.
Less seawall is exposed.

The beach is walkable during most tides.
South Beach is the healthiest its been in over 30 years!

The cost of nourishment this winter was quite reasonable when you compare it with traditional projects using dredges. The average cost was around $1.50 per cubic yard. Seabrook's 1990 project averaged about $2.75 per cubic yard. A project CSE just completed in North Carolina averaged over $6.00 per cubic yard. Yes, maintaining the beach costs money. However, Seabrook has been fortunate to have a plentiful, inexpensive source nearby.

PS: Even after "borrowing" 100,000 cubic yards from North Beach, it's still about the widest beach in South Carolina!

Tim Kana, PhD

Coastal Science & Engineering