Dunes

Dunes serve as a natural barrier to the potentially destructive forces of the winds and waves.  They are the first line of defense against coastal storms and beach erosion.  Being a barrier island, BHI’s sand dunes absorb the impact of storms and high waves which in turn prevent or delay flooding of inland areas and damage. 

The dune monitoring program was implemented by the BHI Conservancy in 2009 in response to accelerated erosion rates observed after the Army Corps of Engineers dredging operations in the Cape Fear River triggered significant sand loss at the intersection of South and West Beach. The Village of Bald Head Island contracted Olsen and Associates to monitor erosion from the low tide line to the beginning of dune vegetation. To complement the work of Olsen and Associates, the BHI Conservancy developed the Dune Monitoring Program to better understand changes in stable vegetation, dune height and stability, and back dune habitat. Bald Head Island Conservancy conducts the following measurements:

  • Transects – A total of twenty-eight dune transects are measured monthly to provide consistent and accurate monitoring of the rates of erosion and accretion on all BHI beaches. Transects begin at fixed landward points in the dunes, and are taken to the first seaward line of vegetation. Transects are perpendicular to the shoreline and are spaced relatively evenly apart, beginning at Beach Access #1 and ending near the last house on East Beach toward Bluff Island.
  • Profiles – In partnership with UNCW, GPS elevation data are collected quarterly along each of the 28 dune transects.
  • Vegetation plots – Vegetation plots are sampled seasonally along each dune transect to determine dune plant number, abundance, and health.

Additionally, to maintain dune health, the Bald Head Island Conservancy, in cooperation with the Village of Bald Head Island, the US Fish and Wildlife Service, NC Cooperative Extension, and the Carolinas Beach Vitex Taskforce works to monitor and eradicate former and existing sites of the invasive species beach vitex (Vitex rotundifolia). Beach vitex rapidly spreads via vegetative growth and seed dispersal, posing a threat to native dune plants and animals on Bald Head Island.  For more information on Beach Vitex and other invasive plant species on Bald Head Island, visit our Native Plants page.


Dune Updates

2015

2015 Dune Updates


The majority of transects measured on Bald Head Island have experiences little change over the past year.  Nineteen of the transects gained or lost less than 2 meters of vegetation, which is negligible when taking into account the dynamism of the beach environment. Some transects showed considerable change; for example, a transect along South Bald Head Wynd close to Bald Head Island Club gained almost 8 meters of vegetation.  This could have been due to newly planted sea oats along the seaward portion of the dune.  A transect near Beach Access 39 along East Beach also showed accretion, gaining about 6 meters of vegetation.  Near the Shoals, there was significant erosion, and almost 10 meters of vegetation was lost over the course of a year.

2014

2014 Dune Updates

Winter 2014-2015 Update

Dune transect graph

Transects

Bald Head Island has experienced a relatively calm winter, with few storms. Additionally dredging activity brought new sand on the beachfront from the point and along south beach. From the graph above, the greatest amount of erosion was recorded at transects 21, 22 and 24 near the Shoals Club. This area typically has some erosion during the winter months as it is on the terminus of the island in a very dynamic area. On average, minor accretion was recorded in the areas of West Bald Head Wynd (transects 6 through 10) and along South Beach (transects 10a through 20). Changes in dune width of about +/- 5 feet are minor and indicate that the dunes remain stable. Dune monitoring will continue through the Spring and early Summer, with a year-end report in mid-Summer.

Profiles

Dune profiles were measured in September 2014. A second set of profile measurements will be measured in April and at that time a comparison of transects will reveal any changes in dune elevation.

Vegetation Plots

Summer 2014 Update

Summer 2014 Vegetation Plots

Transects

Bald Head Island experienced a hurricane on July 3, 2014, and dune vegetation width was measured on July 4, 2014 with only minor changes detected in vegetation width. From the graph above, minor erosion was recorded around transects 10-14 which corresponds with "the Point" area. Minor erosion was also recorded around transect 23-24, which corresponds with the Cape area. This kind of erosion, on the terminus of the island is expected during stormy conditions. However, subsequent measurements in July and August revelealed that these minor areas of erosion accreted back out to pre-storm conditions quickly.

Profiles

Dune profiles were measured in September 2014. A second set of profile measurements will be measured in April and at that time a comparison of transects will reveal any changes in dune elevation.

Vegetation Plots

Vegetation is recorded on a seasonal basis and summer results indicate a healthy dune system with native, dune building species present. No endangered Seabeach amaranth was recorded on any transects nor was any invasive beach vitex. Dune vegetation will be evaluated again in the winter and spring growing seasons to compare species diversity and relative dune coverage.

Response to the Army Corps of Engineers (USACE) study

The BHI Conservancy provided a response to the Army Corps of Engineers (US ACE) study about the Sand Management Plan. The Sand Management Plan Study reviewed how much and where the Army Corps places dredge material when they dredge the channel. The BHI Conservancy believes that the Bald Head Reach portion of the Wilmington Harbor Channel runs too close to the Southeastern point of Bald Head Island. The impact of dredging in this area causes erosion along south and west beaches and in 2009 caused substantial loss of back dune habitat. The Sand Management report contained very little scientific analysis of the sediment budget (where sand goes and where it comes from) nor did it contain a wave study that would show how waves and currents influence the movement of sand. Most disturbing was the complete lack of biological analysis. In short the study had very little objective information. The Corps did, however, reach a conclusion, that the Conservancy agrees with. There should never be a "gap" year like 2009 where all the sand goes elsewhere. The Plan recommended that every year that dredging occurs, 2/3 of the dredge material be put on BHI. To learn more about the BHI Conservancy response please read the entire brief in PDF format  here  .


 

 

Beach nourishment 2013

 

Important documents

Dredging off West Beach point impacts beaches (PDF)

Paper on Endangered and Threatened Species Habitat on "The Point" (PDF)

Effects of Dredging on "The Point" (PDF)

'Line in the sand' video with Stan Riggs (ECU)

NPR report on beach nourishment