Countries Are Building Giant ‘Sand Motors’ to Protect Their Coasts From Erosion

This story initially appeared on Grist and is a part of the Climate 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, referred to as “seashore nourishment,” has turn into a cornerstone of coastal defenses world wide, complementing laborious constructions like sea partitions. North Carolina, for example, has dumped greater than 100 million tons of sand onto its seashores over the previous 30 years, at a price of greater than $1 billion.

The issue with seashore nourishment is apparent. 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.

Seashore nourishment tasks are imagined to final for round 5 years, however they usually disappear quicker than anticipated. Furthermore, a giant 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 displaying up on coastlines world wide. 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 reasonably than towards it. As an alternative of rebuilding a seashore with an excellent line of latest 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 far more upfront funding than regular seashore nourishment—and plenty of instances extra sand—additionally they shield extra land and final for much longer. Developed nations 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 combat sea-level rise. However these large tasks solely work in areas the place erosion is just not but at a essential stage. Which means they’re unlikely to point out up in the USA, the place many coastal areas are already on the purpose of disappearing altogether.

The concept for the challenge 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 offered the thought 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 challenge, which the Dutch name “de Zandmotor,” was an unprecedented endeavor. Boskalis dredged up round 28 million cubic yards of sand from the ocean ground—greater than the Netherlands makes use of on nourishment tasks nationwide in a given yr. Engineers then sculpted the sand right into a hook that curved eastward along the shore, guaranteeing that waves would push the sand northeast towards seashores close to The Hague. Additionally they created a lagoon in the course 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 building on the $50 million challenge, the hook of sand has flattened out, nearly the best way a wave breaks because it reaches the shore.