How to Rebuild an Island by Harnessing Wave Power

In 2019, a group of island nations from the Pacific, including Fiji, Nauru, and Micronesia, issued a climate crisis declaration whereby they alerted to their shrinking territories because of rising sea levels. In a worst-case scenario, many of their islands will no longer be habitable by the next decade. And not only because of the loss of land, but also owing to the salination of their water reservoirs. According to some estimates, 40% of people living in coastal areas are currently at risk. Unfortunately, reverting climate change will require many decades, well beyond the time available for threatened populations. Thus, together with the increasing weight of renewable energy, new strategies are being developed to adapt to the challenges of climate change. One of these approaches is the one followed by a team at MIT, which is studying the way to harness the forces of nature to regain ground lost to the sea. Specifically, they are researching how the power of waves can be channeled towards the creation of sandbars. In just four months, this innovative technology project has reportedly broadened a coastal area by a foot and a half.   

Adaptation strategies had so far included the dredging of sand from seafloors or building barrier walls. These techniques are costly and not too eco-friendly. However, there could be smarter and more sustainable approaches. The team, led by Skylar Tibbits, an associate professor of design research in the MIT Department of Architecture, has been experimenting with the power of waves since 2018. Back then, they worked with two test tanks where they measured the impact of waves on the distribution of sand. That would be the testbed for the techniques that they later applied in the Maldives. To assess the efficiency of their experiments, they used satellite and drone imagery coupled with manual measurements of accumulated sand.

Transforming waves into allies

Indeed, the populations of these Pacific islands have become accustomed to considering waves like an enemy that is unrelentingly eating away their homelands. However, the same energy that gnaws at their coastlines could also become the best ally to protect them. Following their lab tests, Tibbits and his team started implementing the devices that they had designed to control sand flows. The tests carried out in the Maldives were based on heavy-duty canvas bladders sewn together into ramp geometries. Once submerged, the ramps redistribute wave turbulence, so it pushes the sand over them, creating sediment transport. The development of these simple and quickly deployed ramps replicates the behavior of coral reefs or volcanoes in the formation of sand deposits.

First outcomes and prospects   

Throughout 2019, the researchers assessed the efficiency of their system, which has achieved 300 cubic meters of sand accumulation in over four months. This means that an area of approximately 20 meters by 30 meters has grown by roughly half a meter. The long term goal is that these platforms can adapt to weather changes to optimize sand sedimentation, not only in the Maldives but also in other areas of the world. The team has received a National Geographic grant to continue with their research.

Source: MIT