Replenishment alters the shape and structure of the beach, and the way the ocean interacts with it. Storms, tides, and currents are always changing and reshaping beaches. But after beach replenishment, it can take a long time to return the beach to a more normal state.
In the last few decades, studies and anecdotal evidence have begun to confirm the negative safety impacts. An important reference is “The Impact of Sand Nourishment on Beach Safety” by Fletemeyer, Hearin, Haus and Sullivan published in January 2018 in the Journal of Coastal Research1.
The study shows how replenishment alters the shape of the beach, especially here in New Jersey. Typically, New Jersey beaches have what is called a “a low-intensity beach break” where the area in which waves break (from the water’s edge out) is quite wide. Because incoming waves break when they reach a water depth of 1.3 times the wave height, larger waves break farther offshore in deeper water, while smaller ones break closer to shore in the shallows. At least, that was the case prior to beach replenishment.
However, once millions of cubic feet of sand are pumped onto a beach, it’s as if it is high tide all of the time. The beach created is generally much steeper, dropping off more quickly to deep water. This geometry worsens as waves, tides and currents erode the new beach. A steeper beach causes the waves to break over a very narrow surf zone, with a much higher incidence of plunging breakers – waves that rise up suddenly and curl over. The situation becomes worse at high tide when water depth increases by 3-5 feet.
For the casual beachgoer, this means the water drops from knee-high shallows to overhead depth very quickly, with most waves breaking directly on the beach, and breaking more violently, regardless of size. The water of these waves pushes up the steep angle of the new sand beach and drags back with great force. Overall, what was a relatively benign area at the water’s edge becomes hazardous. For strong adults this can be troublesome. For poor swimmers and children, it can be life-threatening.
It seems likely these changes are contributing to an increase in accident rates being reported on recently replenished beaches. In January 2018, the Journal of Coastal Research published another research article on their website titled “Evaluating the Impact of Beach Nourishment on Surfing: Surf City, Long Beach Island, New Jersey, U.S.A.”2 They reported that data gathered by the United States Lifesaving Association in Ocean City, Maryland found a 297% increase in serious aquatic accidents, from 87 to 345, in the year after a beach replenishment in 2006. When the beach was replenished again in 2010, accidents jumped once more by 31%, from 233 to 306.
Here in New Jersey following a Cape May project in 2007, there was a 192% increase in accidents, from 12 to 35. The article states that these injuries were serious ones, including head, spinal, and shoulder dislocations. When you consider these links between beach replenishment projects and beach safety, the probability of these projects leading to injuries and deaths is troubling.
In 2008, so many people were getting hurt on replenished beaches that US Senator Frank Lautenberg called for an investigation. Press release on that here. And he sent this letter to the Army Corps about it.
Using the Cornell University Long and Intermediate WAVE (COULWAVE) Boussinesq wave model, the same article examined the effect of a standard beach replenishment project in Surf City, New Jersey, on the local surf break.
The study concluded that the quality of the surf break was degraded by compression of the surf zone, an increase in the occurrence of “closeouts,” a shift in breaker type toward collapsing breakers, particularly during high tide, and an increase in wave reflection. They found these points to agree with the testimony of local surfers. They determined that it required at least 21–22 months for the surf break quality to return to a pre-project state.
Importantly, the study found “The steepening of the slope of the beach proﬁle in the near shore promotes a shift in breaker type toward surging and collapsing breakers, particularly during high tide, which poses a formidable risk to surﬁng and is also dangerous to bathers.” The greater occurrence of closeouts and the narrowing of the surf zone are also conditions that can lead to reduced safety and an increase in injuries. Again, the link between beach replenishment and safety seems clear.
Other dangers we have noted locally include the formation of sand “cliffs” when storm waves erode newly deposited sand. Not only do these drop-offs create a hazard to people falling from the top of the cliff, they can also trap people at their base between breaking waves and sand during high tide. For examples, see the photos in Figure 1 and 2, taken in Monmouth County, NJ after beach replenishment projects there.
Sand cliff at Monmouth Beach, 2013
Famously, (or infamously) former NJ Governor Jim McGreevey broke his leg while on the beach in Cape May in 2003. The cause? You guessed it, a 4-foot high cliff where the beach replenishment was washing away. More in the NY Times here.
In summary, the dangers of replenished beaches are not only suspected, they have been studied and documented. This is one more reason that replenishment must be reduced or abandoned, at least in its present form, for the good of all visitors to New Jersey beaches.
Here are some more news items about safety and beach replenishments –
Surfrider blog post with an Asbury Park Press Article embedded therein – https://www.surfrider.org/coastal-blog/entry/beachfill-implicated-in-injuries
1) The Impact of Sand Nourishment on Beach Safety by John Fletemeyer, John Hearin, Brian Haus, and Andrea Sullivan; July 2018, Journal of Coastal Research https://www.jstor.org/stable/26296438
2) Evaluating the Impact of Beach Nourishment on Surfing: Surf City, Long Beach Island, New Jersey, U.S.A. by William Dally and Daniel Osiecki; January 2017, Journal of Coastal Research https://www.researchgate.net/publication/325097545_Evaluating_the_Impact_of_Beach_Nourishment_on_Surfing_Surf_City_Long_Beach_Island_New_Jersey_USA