Waves and erosion

Figure 4. The sound side of a barrier island, too, can be eroded by waves. (Photograph by the author. More about the photograph)

Figure 4 shows that rising sea level brings the eroding power of waves to the sound side of barrier islands as well as to the ocean side. Here we see the steep and collapsing face of an old beach ridge along the Roosevelt Nature Trail on the sound side of Bogue Banks. This ridge, like the beaches shown in Figures 2 and 3, was eroded as a result of waves from Hurricanes Bonnie and Fran, but here, too, the slow rise in sea level played a controlling role by bringing the sea to an elevation from which it could reach the ridge.

Note that the eroded remnants of the beach ridge have formed a new beach and marsh in front of the ridge. These sloping surfaces will help dissipate the erosive energy of waves, but they, like the oceanfront dunes, will not offer enough energy dissipation to protect the ridge from further erosion during storm events.

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