Scientists attempt to create artificial islands in the Maldives

Around the world, coastlines are under threat from rising sea levels and intensifying storms. Island states and coastal cities are taking steps to defend themselves, from building sea walls to dredging sand from the seabed and pumping it onto beaches.

In the Maldives, an archipelago of about 1,200 islands stretching 560 miles (900 kilometers) across the Indian Ocean, the Massachusetts Institute of Technology’s Self-Assembly Laboratory and the Maldivian organization Invena are working on a more natural solution. Using submersible structures, they are harnessing the forces of the ocean to cause sand to accumulate in carefully chosen spots to protect the islands — and even potentially create new ones.

Since 2019, organizations have been conducting field trials in the Maldives, where the coastline of nearly every island is eroding.

The various experiments — conducted mostly in shallow waters off a reef south of the capital Malé — involved everything from submerging a net of ropes tied in tight knots to collect sand, to using a material that turns from textile into rigid concrete when sprayed with water to create a barrier that was placed on the seabed to collect sand there.

In another field experiment, a floating garden was installed above a sandbank, to explore whether roots could help stabilize already accumulated sand and collect more.

This may not sound all that groundbreaking. After all, ideas like using mangroves for coastal defense have been around for a while. But there’s serious data and technology behind the work.

The field installations begin as experiments in wave tanks on MIT’s campus in Cambridge, Massachusetts. To determine how to orient the structures and their optimal geometries, the team relies on information about ocean waves and currents collected by tilt sensors in the Maldives, publicly available tide and weather data, thousands of computer simulations, and a machine-learning model trained on satellite imagery to predict how the sand will move.

Skylar Tibbits, founder and co-director of the Self-Assembly Lab, which focuses on materials and processes that enable the formation of objects and spaces, told CNN who hopes the submersible structures could provide a more sustainable method than conventional engineering solutions for reinforcing eroded shorelines. “We are using the natural force of the ocean to guide the sand,” he said.

“The sand wants to be there”

The Maldives, with an average elevation of just one meter above sea level, is the lowest-lying country in the world. Authorities, resort operators and property developers have resorted to dredging and heavy engineering solutions, building retaining walls, breakwaters and groynes to try to deal with the problem.

But these interventions can be expensive, difficult to maintain and harmful to ecosystems.

Pumping and dredging need to be repeated every few years. Retaining walls and other infrastructure can even exacerbate the erosion they are supposed to prevent or correct, especially when the design or construction is of poor quality, or ideas are copied from elsewhere without taking local considerations into account.

Paul Kench, a coastal geomorphologist at the National University of Singapore who was not involved in the MIT and Invena work, has seen evidence of this. His research has shown that structures ranging from retaining walls to boat harbors can worsen erosion and degrade reef productivity.

“The types of engineering solutions we tend to use on continental shorelines really shouldn’t go near a reef island,” he said, but “people tend to use them because that’s what they know.”

The MIT Self-Assembly Lab and Invena’s use of local data works with natural forces, rather than against them, Tibbits argues, “so the sand wants to be there.” With each field experiment, the group says it is advancing its understanding of what materials, configurations, and construction techniques can make sand accumulate in the simplest, most cost-effective, sustainable, long-lasting, and scalable way.

In the short term, Tibbits believes what they have learned can be used to effectively rebuild existing beaches and islands.

The ambitious goal of the collaboration is to create artificial islands. So far, its second field experiment, launched in 2019 in the Maldives, has yielded the most promising results. It used biodegradable, textile-based, sand-filled bladders that were placed in strategic positions to create a sandbank.

In just four months, about half a meter of sand accumulated in an area measuring 20 by 30 meters. Today, the sandbank measures about two meters high, 20 meters wide and 60 meters long.

The material used is expected to last about 10 years, which could make it a more permanent — and therefore more cost-effective — solution than pumping and dredging, Tibbits said.

Scaling sustainable solutions

Other, more natural solutions are being tested and implemented elsewhere. In the Netherlands, for example, the world’s first sand motor—an artificially created sand peninsula that helps waves push sand onto the shore—was built more than a decade ago. In New York, oyster reefs are being replenished to protect coastlines.

While interest in solutions that incorporate nature is growing, they can be a tough sell.

“Those who control the purse strings … are very reluctant to step away from these solidly engineered structures for fear that their money is being wasted,” Kench said.

But a new approach could be crucial. A high proportion of coastal erosion in the Maldives is “anthropogenically forced” by heavy engineering interventions, said Kench, who is currently working with his students in the Maldives to better understand and model how island coastlines change. “Something these bogged-down countries don’t like to acknowledge is that they have had a heavy impact on the islands.”

In the Maldives, the government supports the work of the MIT Self-Assembly Lab and Invena, but that has not yet translated into financial support, Sarah Dole, co-founder of Invena, told CNN .

Late last month, the organizations installed a scaled-up version of their second field experiment, placing six fabric bladders in a ring formation, with the goal of collecting sand to form a sandbar regardless of the direction of waves and currents during the monsoon season. A survey will be conducted in November to verify the results.

Separately, a future project will restore a beach at a new resort development about a 15-minute speedboat ride from Malé.

Together, these trials, which are supported by a grant from the U.S. Agency for International Development (USAID), are trying to show that the group’s work can be successful at scale. “This is going to be very important, and all eyes are on it,” Dole said.

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This content was originally published in Scientists try to create artificial islands in the Maldives on the CNN Brasil website.

Source: CNN Brasil