Coastal erosion is a natural process that occurs through the actions of wind, waves, currents and drainage. Erosion has existed for millennia. It is the key to the formation of our island’s beaches. To understand more about erosion and how it has affected our island see the Erosion Q&A Section and the Resources Section. You can explore the interactive map below to find detail about individual erosion-control structures on Nantucket.
What is coastal erosion?
Coastal erosion is a natural process that occurs through the actions of wind, waves, currents and drainage. It results in the loss of sediment in some places and accretion elsewhere. The process by which sediment, mainly sand, is moved along the shore—and around Nantucket—by wind and currents is called littoral transport or littoral drift.
How does erosion affect Nantucket?
In layman’s terms, erosion shapes our ever-changing coastal environment and, in fact, creates our island’s beaches. Headlands and coastal bluffs erode to form beaches, dunes and offshore sandbars as sand is transported and deposited by waves and wind. When erosion is stopped, downdrift beaches stop growing.
Has erosion always been a fact of life on Nantucket?
Yes, erosion has existed for millennia and has made, and continues to make, Nantucket Nantucket. Our shoreline has always been shifting, as are all shorelines. The fact is that shorelines are not “lines” at all but transition areas between the land and the sea.
How have Nantucketers dealt with erosion over the decades?
Over the years, islanders—on Tuckernuck and Muskeget as well—have opted to relocate structures and infrastructure out of harm’s way, or, accepting the inevitable, simply left them to be destroyed by the ocean. [ In the chapter "Erosion, the Reaper" from his book Nantucket: A Natural History, Peter Brace provides detail about erosion on Nantucket and various attempts to deal with it.]
What local regulatory body is involved in the permitting of erosion-control structures?
The Nantucket Conservation Commission, a body of 7 citizens appointed by the Board of Selectmen, hears applications for proposed work within the jurisdiction of the local Wetland Bylaw and the State Wetlands Protection Act.
What is “hard armoring”?
According to our local Bylaw, hard armoring is defined as “any bulkhead, revetment, seawall, rip-rap, groin, jetty, artificial seaweed, plastic sheeting, or other structure intended, or constructed so as, to prevent or alleviate storm damage, or modify tidal action, wave action, littoral flow, or erosion.” Geotubes are also considered hard armoring.
Is hard armoring allowed?
No, except under certain circumstances. New coastal engineering structures are allowed only under the local Bylaw to protect buildings that were constructed prior to the implementation of regulations in 1978 and were not substantially improved after 1978. Otherwise, a waiver from the regulations must be justified.
If erosion creates beaches and hard armoring installations degrade or destroy them, is Nantucket’s natural shoreline threatened, especially as more and more waterfront property owners attempt to stabilize the beaches in front of their homes?
Yes. Several hard erosion-control projects have already been installed along the north shore and are severely affecting the natural coastline. Most of them pre-date the 1978 State law prohibiting hard- armoring. These erosion-control engineering structures and their effects can easily be viewed on Google Maps. The cumulative impacts of such projects will alter— and are altering—Nantucket’s natural shore, especially if they are allowed to proliferate.
What is meant by “threatened”?
Beaches on which erosion-control structures are installed are, by definition, compromised. Both “soft” and “hard” methods of erosion control generally result in a loss of sand (both on the beach on which the structure is installed and on the coastal areas adjacent to it), narrowing of beaches, loss of habitat and, especially critical for Nantucket, restriction of, or in some cases loss of, public access.
So, when it comes to hard armoring, is the choice to be made between saving structures or saving beaches?
Yes. As Cornelia Dean, former Science Editor of The New York Times, explains in her 1999 book Against The Tide: The Battle For America’s Beaches: Erosion does not threaten the beach per se. Left to confront a rising sea alone, a beach will simply move inland. Decisions to armor the coast are not decisions to save the beach—quite to the contrary. They are decisions to sacrifice the beach, or a neighboring beach, for the sake of buildings. [Page 66.]
Is there no other alternative for the property owner?
Alternatives do exist: more environmentally sensitive options to hard armoring, called “soft” structures. Such erosion-control methods work with Mother Nature, not against her, and have minimal or no adverse impacts. These methods are documented and explained by the Massachusetts Office of Coastal Zone Management on its website. Many such soft structures are permitted by the Nantucket Conservation Commission and installed around the island. [See the interactive map developed by the Worcester Polytechnic Institute students in the fall of 2014 for an inventory of all legally installed hard and soft erosion-control structures on Nantucket.]
Are there any other alternatives?
Yes, there is an alternative that is a win-win for everyone: relocation, the historic way islanders have dealt with erosion and its consequences. Moving a structure landward out of harm’s way, as was done with Sankaty Lighthouse, causes no harm to the coastal environment and has a certain outcome. It “saves” the structure. It also “saves” the beach. The Directors of the ’Sconset Trust are to be recognized—and thanked—for choosing an alternative that is in the best interests of all parties, including Nantucket.