This story initially appeared on Grist and is a part of the Local weather Desk collaboration.
When governments discover themselves combating the specter of coastal erosion, their default response tends to be fairly easy: If sand is disappearing from a seashore, they pump in additional sand to exchange it. This technique, often known as “seashore nourishment,” has grow to be a cornerstone of coastal defenses around the globe, complementing onerous constructions like sea partitions. North Carolina, as an illustration, has dumped greater than 100 million tons of sand onto its seashores over the previous 30 years, at a value of greater than $1 billion.
The issue with seashore nourishment is clear. In case you dump sand on an eroding seashore, it’s solely a matter of time earlier than that new sand erodes. Then you must do it yet again.
Seaside nourishment initiatives are speculated to final for round 5 years, however they typically disappear sooner than anticipated. Furthermore, an enormous coastal storm can wipe them out in a single evening. And the prices are staggering: Dragging in new sand requires leasing and working big diesel dredge boats. Solely the wealthiest areas can afford to do it yr after yr.
Now, after many years of reliance on repeated seashore nourishment, a brand new technique for managing erosion is exhibiting up on coastlines around the globe. It’s known as the “sand motor,” and it comes from the Netherlands, a low-lying nation with centuries of expertise in coastal safety.
A “sand motor” isn’t an precise motor—it’s a sculpted panorama that works with nature relatively than in opposition to it. As a substitute of rebuilding a seashore with a fair line of recent sand, engineers prolong one part of the shoreline out into the ocean at an angle.. Over time, the pure wave motion of the ocean acts as a “motor” that pushes the sand from this protruding landmass out alongside the remainder of the pure shoreline, spreading it down the shoreline for miles.
Whereas sand motors require rather more upfront funding than regular seashore nourishment—and plenty of occasions extra sand—additionally they defend extra land and final for much longer. Developed international locations such because the Netherlands and the UK are turning to those megaprojects as an alternative choice to repeated nourishment, and the World Financial institution is financing a sand motor in West Africa as a part of a billion-dollar adaptation program meant to struggle sea-level rise. However these huge initiatives solely work in areas the place erosion shouldn’t be but at a important stage. Which means they’re unlikely to indicate up in the USA, the place many coastal areas are already on the purpose of disappearing altogether.
The thought for the undertaking got here from a Dutch professor named Marcel Stive, who had watched with frustration as his nation’s authorities spent billions to nourish the identical coastal areas over and over as sea ranges saved rising. Stive introduced the concept to the federal government, which employed a big dredging firm known as Boskalis to construct a prototype on the shoreline south of The Hague.
Even this experimental undertaking, which the Dutch name “de Zandmotor,” was an unprecedented enterprise. Boskalis dredged up round 28 million cubic yards of sand from the ocean ground—greater than the Netherlands makes use of on nourishment initiatives nationwide in a given yr. Engineers then sculpted the sand right into a hook that curved eastward alongside the shore, making certain that waves would push the sand northeast towards seashores close to The Hague. In addition they created a lagoon in the midst of the sand construction in order that locals wouldn’t must stroll for nearly a mile to get to the water. Within the years since Boskalis completed development on the $50 million undertaking, the hook of sand has flattened out, virtually the way in which a wave breaks because it reaches the shore.
