Mapping Oil Spill in Mauritius using Radar Remote Sensing
- Arpit Shah
- Aug 14, 2020
- 4 min read
Updated: Dec 8
MV Wakashio, a bulk carrier owned by the Japanese shipping company Nagashiki, was en route to Brazil after delivering its iron ore consignment to China when human negligence likely caused it to run aground on a reef in the shallow waters off the south-eastern coast of Mauritius on the evening of 25 July 2020. Rough seas, coupled with the limited experience of the Mauritian authorities in handling such maritime disasters, made it extremely difficult to refloat the vessel—or at the very least, extract the 4,000 tonnes of fuel onboard.
The worst fears materialized on 6 August 2020 when the bunker tank ruptured and fuel began leaking into the pristine turquoise waters. With the threat of irreversible devastation looming over the island nation’s famed reefs, lagoons, and beaches, the Mauritian government declared a state of emergency. Calls for international assistance intensified, particularly to France, given the proximity of Réunion Island—an overseas French territory.
Although the seas finally calmed enough by 12 August to allow responders to board the vessel and pump out the remaining oil, it was too late to prevent the initial catastrophe: 1,000 tonnes (≈7,000 barrels) of fuel had already spilled into the ocean and was spreading rapidly. The timely extraction, however, prevented an even greater disaster, as the vessel broke into two just three days later, on 15 August.
For extracting Earth Observation insights at a regional scale and beyond, satellite-based Remote Sensing remains the most efficient and cost-effective technique. With extensive open-access missions such as ESA's Copernicus Programme, virtually anyone—with some training and a standard personal computer—can now analyze satellite imagery and derive meaningful insights. What was once the domain of specialized scientists and research institutions is now accessible to a far wider audience.
And this is precisely what I set out to do. While the detailed methodology for detecting oil spills using Synthetic Aperture Radar (SAR) imagery can be viewed here, the final output from my independent assessment of the Mauritius oil spill extent is shown below.
(Sentinel-1B imagery has a spatial resolution of 5 m × 20 m.)
The devastation caused by the oil spill was considerable. Reports indicated that marine life was dying in significant numbers, while toxic fumes from the leaking fuel were causing discomfort and health issues for residents along the coast. All in all, this incident delivered a major blow to Mauritius’ tourism-dependent economy.
On 11 August, the Finnish microsatellite operator ICEYE released an updated oil-spill extent map (Figure 3 below). It was clear that the affected area was much larger than what my own analysis had shown just a day earlier. Part of this discrepancy may stem from the fact that ICEYE’s radar-satellite constellation is specially calibrated to detect Oil Spills. However, the spill was also expanding at an alarming rate—from 3.3 square kilometres detected by ICEYE on the first day of the leak (6 August) to 27 square kilometres just five days later, as depicted below-
Compared to the Deepwater Horizon disaster—where an estimated 3.19 million barrels of oil leaked into the Gulf of Mexico—this spill was far smaller in magnitude. Yet the increasing frequency of spills in ecologically sensitive regions, particularly in the Arctic Ocean, is deeply concerning. It underscores the urgent need to reconsider global shipping routes, accelerate the transition to renewable energy, and establish robust early warning and emergency-response mechanisms to combat such ecological crises effectively.
I can't help but feel that 2020 is nature’s way of telling us to repair our relationship with the environment—before it is too late.
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