Sand Motor: A New Strategy for Coastal Erosion Management
Coastal erosion is a growing concern for governments around the world. Traditionally, the response to eroding beaches has been to pump in more sand through a process called “beach nourishment.” However, this strategy is not sustainable in the long term, as the newly added sand erodes quickly and requires constant replenishment. Moreover, it is an expensive endeavor that only the wealthiest areas can afford. But now, a new approach called the “sand motor” is gaining popularity and showing promise in managing erosion.
The sand motor is not an actual motor but rather a sculpted landscape that works with nature instead of against it. Instead of adding sand evenly along the shoreline, engineers extend one section of the beach out into the sea at an angle. Over time, the natural wave action of the ocean pushes the sand from this protruding landmass along the rest of the coastline, spreading it for miles. This method requires more upfront investment and more sand than traditional beach nourishment projects but offers long-lasting protection.
Countries like the Netherlands and the United Kingdom have embraced sand motors as an alternative to repeated nourishment projects. The World Bank is also financing a sand motor in West Africa as part of a billion-dollar adaptation program to combat sea-level rise. However, these large-scale projects are not suitable for areas where erosion is already at a critical stage, such as many coastal regions in the United States.
The concept of the sand motor originated from Dutch professor Marcel Stive, who grew frustrated with his country’s repeated beach nourishment efforts. The Dutch government hired Boskalis, a large dredging company, to build a prototype sand motor on the South Holland shoreline. This experimental project, known as “de Zandmotor,” involved dredging 28 million cubic yards of sand from the ocean floor and sculpting it into a hook shape. The sand motor was designed to last for 20 years but is expected to endure even longer.
While the success of the South Holland sand motor has inspired a few countries to replicate the Dutch model on a smaller scale, most nations require international assistance due to the high costs and expertise involved. Many countries settle for concrete barriers, rock walls, and smaller nourishment projects, which have shorter lifespans and can even accelerate erosion in neighboring areas.
West African countries, in particular, face severe erosion threats. The Gulf of Guinea’s coastline is eroding faster than almost anywhere else in the world, with significant economic and health consequences for coastal settlements. The World Bank has provided funding for erosion solutions in West Africa, including a sand motor project in Benin. This small nation is experiencing rapid erosion, with parts of its shoreline receding by up to 45 feet per year. The sand motor in Benin, built by Boskalis with World Bank funding, aims to protect a popular beachfront area that has been heavily impacted by erosion.
However, implementing sand motors in countries like Benin requires more than just the construction of these structures. It also involves shifting development away from the water’s edge, as the Dutch did successfully. This can be challenging in areas where homes and infrastructure are clustered along narrow strips of land. Nevertheless, the World Bank is open to funding managed retreat policies if national governments are willing to pursue them.
In the United States, where beachfront development is extensive, the sand motor approach may not be as viable. Coastal communities in states like Florida require constant infusions of sand to combat erosion, as their beaches have eroded significantly. The urgency for nourishment projects is high, and there may not be enough sand available to build a sand motor. Additionally, moving development away from the shoreline poses political and logistical challenges.
The sand motor offers a promising solution for managing coastal erosion, but its success depends on comprehensive climate adaptation plans that include shifting development inland. While it may not be suitable for all coastal areas, countries that can implement sand motors alongside managed retreat policies can benefit from long-lasting erosion control. As the threat of sea-level rise continues to grow, innovative strategies like the sand motor will play a crucial role in protecting vulnerable coastlines around the world.