In this third in a series of blogs and posts about living on an island, like I do on the Outer Banks of North Carolina in Emerald Isle, NC. And, living on an island is all about living with the ocean. And living with the ocean is all about mitigation techniques that have been employed on the barrier islands along the Gulf and Atlantic coasts to keep the ocean and sounds at bay.
In a previous blog, I examined jetties, one of the first mitigation techniques employed. In this blog, I examine sea walls. New Jersey has used seawalls and other beach armor (hard engineering) to excess, partly because beach development and property preservation was a late 1800’s phenomenon and partly because understanding coastal shore the dynamics was a late 1900’s research discipline. Seawalls are the largest of these structures. They are designed to withstand the full force of the ocean's waves in order to protect endangered property. And, many seawalls do that job very well. They save homes and other buildings that otherwise would have been destroyed. However, over time, they narrow and sometimes even destroy the beaches in front of them. Often, the speed at which a beach erodes will increase when a seawall is put in. Some beach-front property owners consider the loss of the beach a reasonable sacrifice for the survival of their buildings. However, when seawalls wipe out an entire beach, these same property owners sing a different tune.
Other victims of New Jersey's efforts to protect beaches and buildings from erosion are the towns of Sea Bright, Monmouth Beach & Long Branch, beach towns on the Jersey Shore, just South of Sandy Hook National Park. The use of seawalls, groins, jetties, bulkheads, revetments, and beach nourishment since the late 1800s has made this stretch of the shore one of the most heavily engineered sections of ocean front in the world. The seawall built between Sea Bright and Monmouth Beach in New Jersey is one of the longest (almost 5 miles) and tallest (over 8 feet) in the United States. Construction on this wall started in the mid to late 1880's to protect the railroad that brought sea bathers to these two communities. By the late 1990’s, tens of millions of dollars had been spent on maintaining the wall and the property it is protecting. Over the years, tons of sand has been dumped at the foot of the wall to replace lost beaches. Despite the wall and all the money spent on it, the beaches have (at one time or another) all but eroded completely leaving seawalls or the detritus of previous old seawalls, groins, and bulkheads to litter the sea for hundreds of yards. By gradually removing the beach in front of it, every seawall must eventually be replaced with a better (i.e., bigger), more expensive one. Today, in Sea Bright and Monmouth Beach, residents have built “walkovers,” structures that enables homeowners to traverse the current eight-foot seawall that separates the town from the beach.
Sea walls are examples of hard engineering, a term that also encompasses bulkheads, revetments, groins, jetties, and breakwaters built of wood, stone, concrete, or steel. These hard structures purposely interfere with waves and currents, all in an effort to retain sand and hold back tidal waters. Bulkheads and seawalls can protect upland property from damaging storm waves, but they do nothing to abate the erosion of the beach fronting the structure. In fact, such hard shore-parallel structures such as bulkheads and seawalls may accelerate beach erosion. When waves wash up against the walls, waves reflect back towards the ocean with much more energy than if the wall wasn't there. These reflected waves often cause the sand beach in front of a seawall to erode twice as fast as an adjacent beach without a seawall. As the beach continues to erode, the seawall may also block natural replenishment of sand from the dunes or cliffs behind the wall. Reflected waves and the diminished sand supply create a beach profile that is very steep and deep. Waves often reach the seawall without even breaking. Building such hard structures parallel to retreating shorelines is a recipe for permanent beach loss.
In the next number of blogs, I will continue to examine how mitigation techniques have been employed on the barrier islands along the Gulf and Atlantic coasts. That being said, to learn more about life in Emerald Isle, NC, go to my website, www.EIHomesforSale.com and request my free Guide to Living Were You Vacation or text your email address to: 919-308-2292.
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