Building Beaches: Beach Nourishment in the United States
Summer in North America: as the weather gets hotter, people flock to coastal areas to cool off. While many visitors to coastlines think of these areas as naturally formed, most popular shorelines are carefully engineered spaces. If you’ve been or are planning to go to a beach this summer, whether on the Great Lakes, West, Atlantic or Gulf coasts, there’s a good possibility that you will be walking on a beach built through beach nourishment. Beach nourishment involves dredging sand from a “borrow area” offshore, pumping it onshore, and sculpting beaches that both mimic and enhance the original shoreline. Building up beaches has a long history in the United States and there are many competing interests involved in nourishment projects. Understanding these competing interests, and the pros and cons of nourishment, is increasingly important as oceans become more dynamic as a result of climate change and eat away at our shorelines.
There are many reasons for nourishing coastlines. Larger beaches protect coastal settlements while maintaining a view of the ocean, a space for leisure, and less obstruction or destruction of the natural environment for those organisms that rely on sandy spaces for habitat or reproduction. Nourishment (sometimes referred to as restoration) is known as soft engineering: instead of building sea walls or levees (hard engineering), nourished beaches can protect shorelines from storm surge by giving waves material on which to chew. An Army Corps of Engineers project manager referred to a nourished beach as a “sacrificial buffer” against storm surge and erosion. Coastal buildup has been linked to high property values and increased tourism. By one estimate, if beach nourishment projects ceased in North Carolina, coastal property values would drop by 17-34%. However, funding for these projects is currently being debated throughout the United States, as climate change enhances the need for bigger and more frequent filling.
New York State has the longest history of nourishment in the country. The first beach nourishment project was the construction and expansion of the shoreline off of Coney Island and Brighton Beach. At the turn of the twentieth century, visiting the shore for saltwater bathing became a popular health cure. The combination of sun and sand was thought to remedy a variety of diseases arising from the constriction of humans into dank, dark, and polluted urban spaces. As rural farmers and European immigrants flocked to cities like New York and Philadelphia, diseases such as rickets, tuberculosis, whooping cough, and pellagra spread rapidly. Progressive Era health officials sent their immigrant patients to Coney Island and Atlantic City, since all of these illnesses were believed to be cured, or at least alleviated, by exposure to salt and sun.
The City of New York developed plans to build a bathing beach and pier at the turn of the twentieth century, but it took almost 20 years to work out the legalities of transferring ownership of the beachfront property from private landowners to the city. This was complicated by the fact that many of these landowners were loath to give up their shore front property, because they charged beachgoers to sunbathe. By October 1921, the City passed legislation allowing them to transfer titles for beachfront property in the same manner that property was acquired for public road projects. The shoreline along these areas was sparse and eroding slowly; high tide reached the base of the buildings built along the water. This meant that an enormous amount of sand would need to be relocated to construct both a bathing beach and a pier.The project proved to be extremely expansive, requiring both hard and soft engineering. To secure the beach, 16 groins and jetties were built along the shoreline to stop sand from shifting too much, and a boardwalk was built 13 feet above traditional high tide. After the boardwalk and support structures were built, the beach fill was brought in. In 1923, 1,700,000 cubic yards of sand were deposited to create a bathing beach. The new high water mark was extended 330 feet seaward. The sand was pumped from four separate borrow areas no more than 3,500 feet off the coast. The total cost of the beach improvement was believed to be about $1,900,000—with half of that being spent on the boardwalk. Improvement of the beach continued throughout the first half of the twentieth century and maintenance is still required to maintain the beachfront.
The cost and effort to maintain filled beaches became painfully clear after Hurricane Sandy: the storm surge happily chomped down on the Eastern Seaboard’s nourished beaches. It was estimated that in one stretch of New Jersey, the storm eroded over 500,000 cubic yards of sand; 43% of New Jersey beaches lost 50-100 feet of beach. New York beaches were similarly affected. This type of unprecedented loss of sand (it would usually take almost a decade to lose this much sand by natural erosion) is prompting many to wonder whether these nourishment projects can be sustained over time.
Nourished beaches require constant care and a large amount of monetary investment, most of which comes from public funding. For example, Virginia Beach required $9 million of nourishment after Sandy. That was the 49th time that stretch of coastline had been built up since 1951. Most nourishment projects are subsidized by the federal government, with taxpayers picking up between 65% and 95% of the tab. A 1996 estimate placed the national expenditure for beach nourishment at $100 billion annually. It’s likely even more, as this estimate is almost 20 years old and does not account for projects on the West Coast (a list of all Pacific coast projects can be found here).
But such large public spending is being questioned, as climate change promises more frequent and stronger storms. In addition to needing more money for constant nourishment, the process is getting more expensive and difficult for certain areas. As of 2012, Palm Beach, Broward, and Dade counties in Florida ran out of sand in their borrow areas and have been looking for alternative locations both inland (the Everglades) and further offshore (Bermuda) to supplement their rapidly eroding beaches. While many officials question the continued nourishment of these spaces given the onslaught of higher tides, others point to concerns about the impact of a diminished shoreline on wildlife that utilize sandy beaches for habitat and reproductive purposes.
When I started researching the topic of beach nourishment, my main interest was the environmental impact of these huge projects. I expected that this would be well-studied ground, but was surprised to find who had been doing the research. In fact, in 1993, Walter G. Nelson, a professor of ocean engineering and environmental science, called for careful study designs for studying the impact of beach nourishment on ecological communities. However, by 2005, marine science researchers Charles Petersen and Melanie Bishop found that only 11 % of studies included both spatial and temporal controls, 56% stated conclusions that were not supported by the data, and 49% did not reach publication standards for citations and synthesis of previous research on the subject. More damning, the authors found that most studies were conducted by project promoters. Basically, most studies of beach nourishment and its impact on the environment are performed by interested parties and lack rigorous scientific parameters.
While there are limited rigorous studies of the impact of beach nourishment, several journal articles suggest that both dredging and depositing impact most organisms only in the short term. Dredging caused signs of stress in coral colonies off the southeastern Florida coast; during active dredging corals developed patchy bleaching, tissue swelling, and increased mucus production that damaged the colony. However, the secession of dredging reduced and sometimes entirely alleviated these symptoms. Similarly, populations of clams and crabs on or near the shoreline declined when sand was deposited but seemed to recover within a year of deposition. Studies have shown that sea turtles will lay clutches on a beach that has been nourished, but those visits drop off for the first year and later rebound. I don’t mean to downplay concerns about environmental impact: the temporary depletion of a population or the increase of stress is no small matter, especially as climate change changes ecological stressors in ways that scientists may not be able to currently evaluate or predict. Stress levels increase corals’ susceptibility to marine disease and decreased population consistently might cause genetic bottlenecks or other unforeseen consequences. But it appears that ecosystems may recover quicker than one might expect.
Perhaps surprisingly, the bigger concern is not the deposition of sand but the type of sand deposited. Both sea turtles and horseshoe crabs migrate to sandy beaches to reproduce. Sea turtles are endangered from poaching and bycatch. Horseshoe crab numbers are beginning to fall, as are the number of endangered red knots that depend upon their eggs for sustenance while migrating. Environmental activists have recommended beach nourishment to increase the availability of nesting spaces for these animals, but they have concerns about the type of sand deposited. Sand grain size is important: if it’s too large or too small, the weight of the sand could crush eggs or make it impossible for turtles to dig into or out of nests. In addition, grain size changes the permeability of moisture and heat to the eggs of both turtles and horseshoe crabs. Exchanging one type of sand for another also affects egg development. As South Florida ran out of sand, local governments and engineers looked towards other sources. Aragonite sand from the Bahama Banks is similar in grain size to Florida’s silicate based sand; researchers sought to test if the sand impacted sea turtle nesting. The same number of eggs hatched and emerged from nests. However, temperature monitoring showed that the aragonite nests were consistently colder than the silicate nests. Reptilian sex is determined through egg temperature during important developmental stages. Colder conditions skew sex rations male, meaning that fewer females were born, which has long term demographic consequences for turtle populations. To ensure that beach nourishment is providing not just space but the proper environment for reproduction, sand consistency must be closely monitored.
Beach nourishment is now at the center of conversations about climate change, environmental protection, natural resource management, and human interaction with these spaces. While I’ve outlined major engineering and environmental reasons for nourishment in the United States, people most often support nourishment because they like to spend a day at the beach. During the original dredge and fill of Coney Island, perfectly good borrow sand was wasted when beachgoers saw its reddish copper color. Boosters were willing to pay more for pristine, white-colored beaches. The way we dredge and nourish tries to take into account engineering best practices and the requirements of native organisms, but it is also predicated upon the aesthetic ideal of what a beach should look like. The importance of beaches for coastal defense, habitats and hatcheries, and leisure makes it especially difficult to untangle conversations about beach nourishment in America today. More pressing, we must figure out how to balance these intertwined expectations as rising seas eat away at coastlines.
Featured Image: Surfers Paradise’s beaches need constant maintenance. “2014-04-07 building sandcastles” by Flickr Commons user Sheridan Tighe under Creative Commons license (CC BY-NA-SA 2.0)