On a freezing winter day along the south-central coast of Holland, two beachcombers, hunched against the wind, stroll along a crescent of sand extending more than half a mile into the North Sea. Nearby, a snowkiter skims over the 28 million-cubic-yard heap of dredged sediment spreading along the shore. If all goes as planned, the mound will eventually disappear, rearranged by ocean currents into a 12-mile-long buffer protecting the coastline for the next two decades.
This is the Sand Engine, one of the latest innovations from Dutch masters of flood control technology and designed, as the national water board Rijkswaterstaat says, so that “nature will take the sand to the right place for us.”
After having constructed the country’s vaunted system of sea gates and dikes, Dutch planners and engineers are now augmenting it with new technology enlisting nature to keep the water at bay. “Normally, there is a lot of erosion here,” says hydraulic engineer Mathijs van Ledden, sweeping an arm toward the snow-covered spit snaking around an elongated lagoon. Van Ledden is a flood risk reduction specialist with Royal HaskoningDHV, a Dutch engineering consultancy involved in creating the Sand Engine, currently 2.2 miles wide.
“This big reservoir of sand should re-nourish the rest of the coast in time,” he says, gesturing toward the skyline of The Hague, several miles away.