As the tides of change lap at the shores of our planet, coastal defenses are being tested like never before. The specter of rising sea levels and the fury of intensifying storms loom large over island states and coastal cities. In response, a diverse array of strategies has been deployed, from the sturdy construction of seawalls to the industrious dredging of sand from ocean floors to replenish eroding beaches.

In the Maldives, a tapestry of approximately 1,200 islands strewn across 900 kilometers of the Indian Ocean, a unique approach is being woven by the Massachusetts Institute of Technology (MIT) Self-Assembly Lab and the Maldivian organization Invena. They are harnessing the very forces that threaten the islands to reinforce their defenses. Submersible structures are being utilized to direct the ocean's energy towards the strategic accumulation of sand, an endeavor that could not only shield existing islands but also midwife the birth of new ones.

Since 2019, this alliance has been conducting field tests in the Maldives, where the relentless erosion of shorelines is a pervasive concern. Their experiments, primarily in the reef flats south of the capital Malé, have taken a myriad of forms. From the submersion of tightly knotted ropes to the transformation of textile into rigid concrete barriers, each initiative is a testament to the marriage of innovation and necessity.

Yet, these are not mere acts of desperation but are underpinned by a robust foundation of data and technology. The prototypes in the field are preceded by meticulous experiments in wave tanks at MIT's campus in Cambridge, Massachusetts. The orientation of the structures and the optimization of their geometries are informed by a chorus of data: tilt sensors in the Maldives, publicly accessible tide and weather information, and a plethora of computer simulations. A machine learning model, trained on satellite images,预测s the dance of sand particles.

Skylar Tibbits, the visionary behind the Self-Assembly Lab, speaks of a future where the submersible structures become the vanguard of a more sustainable approach to coastal reinforcement. "We’re using the natural force of the ocean to guide the sand," he remarks, "The sand wants to be there."

The Maldives, a nation barely a meter above the waves, stands as the world’s lowest-lying country. Its officials, resort operators, and real estate developers have traditionally turned to dredging and hard engineering solutions. However, these interventions often come with a hefty price tag, are maintenance-intensive, and can disrupt delicate ecosystems. The cycle of pumping and dredging is a Sisyphean task that must be repeated every few years, and the very infrastructure intended to curb erosion can sometimes exacerbate the problem, especially when designed without consideration for local nuances.

Paul Kench, a coastal geomorphologist at the National University of Singapore, has observed how structures like seawalls and boat harbors can worsen erosion and diminish reef productivity. "The kinds of engineering solutions that we tend to use on continental coastlines shouldn’t really go anywhere near a reef island," he cautions, yet they persist due to familiarity.

The collaboration between MIT and Invena is a testament to working with, rather than against, nature's forces. "So the sand wants to be there," Tibbits argues, as each field experiment furthers their understanding of the most effective materials, configurations, and techniques for sand accumulation.

In the near term, Tibbits is confident that their learnings can be applied to restore beaches and islands. Their ambitious goal is to cultivate artificial islands, a vision that began to take shape with their 2019 field experiment. Biodegradable, sand-filled textile bladders were strategically positioned to form a sand bar, and within four months, a significant accumulation of sand was observed.

The material is anticipated to endure for a decade, potentially offering a more permanent and cost-effective solution than traditional methods. Other natural solutions, such as the Netherlands' sand motor and New York's oyster reef restorations, are gaining traction worldwide.

Yet, shifting from traditional engineering structures to more natural solutions is often met with resistance. "Those who have control of the purse strings … they’re very reluctant to move away from these solid engineering structures," notes Kench, highlighting the challenge of breaking away from entrenched practices.

In the Maldives, the government's support for the innovative work of MIT and Invena has yet to translate into financial backing, according to Invena's co-founder Sarah Dole. Undeterred, the organizations have recently installed an expanded version of their experiment, aiming to collect sand and build a sand bank regardless of the monsoon's whims. The results of this scaled-up trial will be scrutinized in the coming months.