Satellite data detects hidden waste sites leaking into waterways

Every year, millions of metric tons of plastic waste end up in oceans, harming hundreds of species and their ecosystems. Most of this waste comes from land-based sources that leak into watersheds.

Writing in the journal Plos One, researchers said that efforts to address this issue require better understanding of where people dispose of waste on land.

Current resources to detect and monitor such sites - both official sites and informal or illegal ones - are lacking.

In recent years, the use of computational tools such as neural networks have been used to analyse satellite data to get a greater understanding of the Earth’s surface.

Researcher Caleb Kruse, of Earthrise Media, California, developed a new system of neural networks to analyse data from the European Space Agency’s Sentinel-2 satellites and demonstrated its potential for use in monitoring waste sites on land.

To evaluate the performance of the new system, the researchers first applied it to Indonesia, where it detected 374 waste sites – more than twice the number of sites reported in public records.

Broadening to all countries across Southeast Asia, the system identified a total of 966 waste sites – nearly three times the number of publicly recorded sites – that were subsequently confirmed to exist via other methods.

The researchers demonstrated that their new system can be used to monitor waste sites over time. In addition, they showed that nearly 20 per cent of the waste sites they detected are found within 200m of a waterway, with some visibly spilling into rivers that eventually reach the ocean.

These findings, as well as future findings using this system, could help inform waste-management policies and decision-making, the researchers believe.

The data is also publicly available which means that stakeholders can use it to advocate for action within their communities. Looking ahead, the researchers plan to refine and expand their new waste site-monitoring system globally.

“For the first time, Global Plastic Watch arms governments and researchers around the world with data that can guide better waste management interventions, ensuring land-based waste doesn’t end up in our oceans,” the authors wrote.

In December, nonprofit group Carbon Mapper began using observations from a Nasa satellite to discover the landfill sites responsible for emitting the most methane.