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A two-kilometer-wide sandbar bends off the Dutch coast near The Hague. On sunny summer days, the sandbar is dotted with beach towels, and children play in the small lagoon that runs down its middle. The natural wave break makes the spot perfect for kite surfing and swimming. But this vacationer’s dream will not last: over the next few decades, this sandbar—a US $78-million artificial construction—will erode away. Yet the sandbar’s death will serve a greater purpose: protecting the Netherlands’ natural beaches from unrelenting erosion.
Every year, the Dutch government shells out millions of dollars to dump sand on receding beaches, shoring them up against an ever-encroaching sea. But that method is expensive, and requires constant upkeep. And, as scientists have shown, such beach nourishment schemes can be deadly to local wildlife. So in 2004, Dutch politicians and scientists set out to devise a long-term solution that would do less harm to the ecosystem and stem the drain on their finances.
Two years later, the coalition put forward its plan: the Sand Engine, an artificial peninsula built from more than 20 million cubic meters of sand designed to erode. As the team envisioned it, sand from the eroding Sand Engine would be shuttled to nearby beaches through the natural process of longshore drift. The Sand Engine would provide a gradual, long-term supply of sand—rather than a dump every few years.
Marcel Stive, a coastal engineer at the Delft University of Technology in the Netherlands, and one of the creators of the Sand Engine, says that as well as shoring up the beach, the slow spread of sand was designed to prevent the damage to worms, mussels, and other tiny organisms that results from more traditional beach nourishment techniques. Such a huge initial addition of sand was expected to damage the ecosystem directly at the Sand Engine, but only during the initial build. “The idea of this large nourishment is that sand will spread to adjacent beaches in both directions, so you won’t have to come back for 20 years,” he says.
Construction on the Sand Engine finished in 2011, and an interdisciplinary group of scientists has monitored the project ever since. After six years, the results look promising, and experts around the world are taking notice.
“It’s the best idea in quite a while” for reconciling the environmental and economic concerns of beach nourishment, says Charles Peterson, a beach ecologist at the University of North Carolina at Chapel Hill.
Arjen Luijendijk, a coastal engineer at the Delft University of Technology who also worked on the Sand Engine, says officials in Peru, the United Kingdom, and the United States have expressed interest in importing the design. The United Kingdom went one step further and built a small-scale version of the Sand Engine in Poole Bay, on England’s southern coast, in 2015.
From a coastal protection perspective, the Sand Engine is delivering on its promise, says Luijendijk.
“We clearly see that the sand from the Sand Engine spreads in a down-shore direction,” he says. “It’s impacting more than six kilometers of coast. It does its job.”
Luijendijk says the Sand Engine could keep working for 20 to 30 years, mitigating its $78-million initial price tag. According to Stive, the Sand Engine costs less over time than traditional beach nourishment.
But in its effects on the ecosystem, the Sand Engine hasn’t quite lived up to the scientists’ dreams. Ecologists working on the project say the shoreline has changed far more than was anticipated.
The populations of small organisms living in and around the Sand Engine have changed significantly says Simeon Moons, a marine ecology doctoral candidate at the NIOZ Royal Netherlands Institute for Sea Research. Moons’s research shows that the area around the Sand Engine was recolonized quickly following construction, but the species that moved in were different than the ones that were there before.
The Sand Engine is spreading sand six kilometers down shore, and that’s how far the ecological effects are reaching, too. But whether these changes will be harmful to the beach ecosystem over the long run is difficult to predict, says Moons.
Orrin Pilkey, a geologist at Duke University in North Carolina, says the ecological changes are important to note, but should not negate the overall benefits of the project. “If it changes the species, it may be damaging, but not as damaging as dumping sand and killing everything,” he says.