With 20% of the country below sea level, the Dutch are more vulnerable to rising sea levels than most. Cheryl Katz describes the latest innovation in flood management, a “28 million-cubic-yard heap of dredged sediment spreading along the shore”:
The Sand Engine is the signature project of Building with Nature, a consortium of Dutch industries, universities, research institutes, and public water agencies looking to harness natural systems for next-generation hydraulic engineering. Completed in late 2011 at a cost of 50 million euros ($67 million), the Sand Engine’s goal is to provide long-term fortification for eroding beaches as ocean currents gradually redistribute its dredged material. Until now, this coastline needed sand replenishment every five years, requiring expensive dredging that damaged marine ecosystems.
The Sand Engine will feed beaches for about 20 years at half the price, said Marcel Stive, chair of coastal engineering at Delft University of Technology (TU Delft) and principal creator of the technology. “At this moment, this is the safest coast we have,” Stive said. When the sand is fully spread out, it will protect 20 kilometers (12.4 miles) of shoreline from the current rate of sea-level rise, he said. If the amount of water increases, “we’ll just add more.”
(Photo: Dutch Sand Engine Flight 11 under construction on the coast between Ter Heijde and Kijkduin in September 2011, courtesy of Rijkswaterstaat. By Joop van Houdt)