Barrier Island Migration

Harvested from Google Earth, this image speaks volumes on the issue of barrier island migration.  The principle is that during periods of sea-level rise, barrier islands will “migrate” inland via erosion and long-shore transport of sediment followed by its deposition elsewhere.  All this is facilitated by storm-driven wash-over events, such as those that occurred during Superstorm Sandy, that “push” (the actual mechanism is more akin to disassembly and reassembly) the barrier island back towards the mainland.  Conversely, during periods of sea-level fall, barrier islands will relocate sea-ward due to reduced erosion and increased near-shore sediment deposition at and just beyond the ocean-front margins.

Google Earth screen-grab of the Holgate-Forsythe border

The image here is the south end of Long Beach Island (LBI), showing the populated, and “hardened”, area of Holgate in Long Beach Township and the preserved natural area of the Forsythe Reserve to its South.  For the most part, fortification has stabilized the developed portion, but for anyone who is familiar with the area, it has come at the expense of the beach (hardening a shoreline often accelerates erosion at the beach front) itself, and many ocean-front houses exist under a constant state of threat by waves and surge, while the preserved natural area has been allowed to follow the natural path of Westward migration and thus has self-maintained a healthier beach profile.

 

Some may take this information as proof that fortification/hardening of the beach front works, but many experts in the field feel that what some consider a permanent solution is actually a temporary fix, and likely provides a false sense of security by convincing people to stay-put, actually putting them in harm’s way by providing erroneous reassurance.  Bearing in mind that rising waters, storms like Sandy, and likely time itself may eventually prove futile the efforts made to nail-down the island where it currently lies.

 

Another interesting point to note is that, while the Forsythe Reserve area did indeed experience over-wash and breaching during Sandy, these breaches have filled in via natural sediment transport, requiring no human intervention, since the event.