By Vasudevan Sridharan | 2026-03-23

As a rising tide of plastic debris clogs the world's rivers and oceans, governments and scientists are turning to space for solutions, with satellite imagery emerging as a critical tool to track and clean up marine litter.

In India, researchers, conservation groups, and government agencies have started to use remote sensing technologies to identify plastic pollution hotspots and understand how such waste travels to the sea.

The use of satellite data is particularly relevant for India, whose long coastline and dense coastal populations contribute to marine litter. Rivers and urban runoff transport large volumes of plastic waste into coastal waters.

Ocean plastic

To monitor the man-made litter filling up India’s oceans, the country has built a dedicated fleet of ocean-observation satellites, including Oceansat‑3, which the Indian Space Research Organization (ISRO) launched in 2022.

Oceansat‑3 carries instruments such as the Ocean Color Monitor-3 (OCM-3), which offers improved resolution for monitoring chlorophyll, phytoplankton and water quality.

Oceansat‑3 satellites are part of the broader Oceansat series designed to study ocean color, surface winds, and biological activity in the seas surrounding India.

Although the Oceansat program was first developed for fisheries forecasting and oceanographic research, scientists are now using its datasets to study marine pollution.

Satellite-derived information on ocean currents, phytoplankton blooms, and sediment movement helps researchers understand how floating debris travels across the Indian Ocean.

Further, the country is combining satellite monitoring with in-situ sensors and coastal observation systems.

The Indian National Centre for Ocean Information Services has deployed buoy-satellite integrated systems to collect real-time data on water quality parameters such as salinity, temperature, dissolved oxygen, and nutrient concentrations.

Data gathered by the state-run entity is transmitted via satellite to monitoring centers for analysis and forecasting coastal conditions.

'Ghost Gear'

Beyond the governmental efforts, conservation organizations are experimenting with satellite-based approaches to identify marine litter hotspots.

The marine program run by the conservation non-profit WWF‑India has explored the use of satellite imagery and geospatial analysis to track floating debris along India’s coast and identify priority intervention areas.

"Plastic pollution in India’s marine and coastal waters is a serious and growing concern," WWF-India Marine Conservation Program associate director Vinod Malayilethu told BlueShift.

He noted that large volumes of mismanaged plastic waste enter the ocean from rivers, coastal cities, ports and fishing activities.

"India is among the significant contributors to marine plastic leakage globally, and studies have documented high concentrations of microplastics along beaches, estuaries and nearshore waters," Malayilethu said.

"Abandoned Lost Discarded Fishing Gear (ALDFG), often referred to as 'Ghost Gear,' adds to the problem by continuing to trap fish, turtles and other marine life, damaging habitats such as coral reefs and seagrass beds," he said.

"Key learnings from ghost gear initiatives show that ALDFG is both an environmental and governance challenge, requiring prevention as much as retrieval," Malayilethu explained.

"Projects have demonstrated that community-led reporting and retrieval, fisher engagement, gear marking and incentive-based buy-back upcycling or recycling schemes significantly improve recovery rates and accountability," he said.

"However, major challenges persist, including limited data on the scale and location of submerged gear, high retrieval costs, weak traceability systems, lack of port reception and recycling infrastructure and unclear liability once gear is lost at sea."

Tech innovation

The integration of satellite monitoring with artificial intelligence is expected to accelerate these efforts.

Machine-learning algorithms can analyze thousands of satellite images to identify debris clusters, and can help to track how the clusters shift with ocean currents and seasonal monsoon cycles.

Researchers -- among them University College Dublin School of Geography assistant professor Srikanta Sannigrahi -- say this could eventually enable near-real-time monitoring of plastic pollution across large ocean regions.

"Satellite remote sensing combined with machine learning offers cost-effective, large-scale monitoring that traditional beach surveys cannot match," Sannigrahi told BlueShift.

Sannigrahi was one of the authors of a research paper that developed novel classification algorithms to map the floating debris.

Scaling his research to map plastics in vast waterbodies would be "enormously helpful," he said.

"Our automated Python-based pipeline is designed for transferability," he said. "We trained on Mediterranean data and validated successfully on geographically distant sites."

"Scaled globally via cloud platforms like Google Earth Engine, it could systematically monitor the approximately 1,000 rivers responsible for 80% of ocean plastic inflow," he explained.

It could "identify accumulation hotspots after flood events, track seasonal dynamics driven by monsoons and currents, and – critically – provide policymakers with evidence to evaluate whether interventions like single-use plastic bans are actually reducing ocean litter loading over time."

Indian application

Many of these approaches rely on data from the Sentinel-2 satellites operated by the European Space Agency, whose multispectral sensors capture ocean surface reflectance across several wavelengths.

Indian researchers have replicated the same techniques along the country’s coastlines.

A study analyzing satellite imagery over coastal waters near Puducherry used Sentinel-2 data and machine-learning models to detect floating marine litter.

By combining spectral indices such as the Floating Debris Index (FDI) with a random forest classification model, the researchers were able to identify plastic debris with an accuracy of more than 96% in test classifications.

"This [study] confirms our approach transfers to Indian waters," Sannigrahi said.

"The Indian Ocean remains severely under-sampled compared to other oceans, making satellite-based monitoring especially valuable here. Deploying our system at major Indian river mouths would be a high-impact next step."

Satellite detection has limitations. Plastics are easiest to identify when they form large floating patches, but smaller fragments and microplastics remain difficult to detect from space.

Nevertheless, remote sensing is increasingly seen as an indispensable tool for monitoring how marine pollution moves through coastal waters, with satellites providing governments and environmental organizations with critical data.

This is needed to plan clean-up operations and prevent further contamination.