by Dr. Lenore Tedesco, Executive DirectorThe interface between land and sea is a magical place and the lure of the coast is undeniably strong. There are volumes of research out there seeking to prove that as humans, we have an innate draw to the sea. For so many of us, we don’t need proof. The beach is our happy place. It’s a place of wonderful memories and the provider of calm moments. It has also rapidly become something much more, and perhaps we are trying to make it more than was ever intended.
The beach system is a keystone of the shore economy and something we now desperately rely upon, and the beach and dune complex provides critical protection to our communities. To meet these two needs, we have set upon a course of engineering our shorelines to provide maximum benefit for recreation and to provide protection during storms. There are some ancillary benefits to wildlife, but there are also negative impacts as well.
Beaches are full of energy, and when you spend time at the beach, it’s easy to notice the dramatic changes that constantly take place. They have a seasonal rhythm that adds to their mystique, but they are also on a trajectory of change being driven by both the human engineering of the beach and Mother Nature’s will. It is this interplay of natural and artificial manipulation that now dominates our coastal story.
Beach replenishment is a way of life for coastal communities, and Seven Mile Island is no different. However, engineered beaches are built to be broad and flat, shaped very differently than what Mother Nature would create. The flat beach is designed to be higher and the dunes much wider in an effort to provide resilience. This design does provide resilience, but it does so on a relatively short-term basis.
The big variable of our ever-changing beaches is sea level. Beaches are markers of sea level, and tides rise and fall around this central point. Sea level is not a constant, though. It has risen nearly 11/2 feet since the early 1900s and almost 7 inches since the 1980s – and it continues to rise at ever accelerating rates. Natural beaches respond to sea level rise by moving westward to higher ground to reestablish themselves relative to that new sea level. When we built our communities, we set a fixed line with the beach to the east of the dunes and the town to the west – and we hold the beach in place. Because we don’t allow the beach to move to higher ground, with each storm, the beach system erodes. When storm energy has time to reorganize the beach to a configuration that matches current sea level and energy, it does. Thus, we find ourselves in a cycle where we have significant storm-driven beach erosion followed by repetitive beach replenishment projects.
Engineered beaches have become a fact of life for our communities, and we rely on this as a coastal protection strategy. It’s an expensive strategy, and as sea levels continue to rise at accelerating rates, and as both the frequency and intensity of coastal storms increases, we should expect that the replenishment cycle will become shorter and the costs will increase. We have set ourselves on a course of never-ending beach construction followed by erosion. This is now a necessity of island life, and strong communities are planning for these costs.