Change Detection Analysis Using Sentinel-1 Satellite Data with SNAP and GEE Regarding Oil Spill in Venezuela

In Venezuela, according to a report by the National Aeronautics and Space Administration (NASA) dated September 2021, up to 50,000 oil spills at sea have been monitored in the 2010–2016-time frame. In the current two-year period, the situation does not seem to have changed: the state refinery of the Venezuelan oil company Petróleos de Venezuela, S.A. (PDVSA), located near El Palito (Carabobo), is estimated to have been responsible for nearly 100,000 barrels of oil spilled in just one year. The aforementioned spills, with the intensification of extraction, transport and storage operations, have given rise to a greater number of accidents resulting in uncontrolled dispersion of material, endangering local marine-coastal ecosystems. The one that took place in July 2020 stands out, reconstructed a posteriori using satellite images that have highlighted its geo-environmental impact. Remote sensing has played a fundamental role in identifying and monitoring the spread of hydrocarbons; in the present study, the same event was analysed using Sentinel-1 Synthetic Aperture Radar Image (SAR) Change Detection techniques. The use of the desktop software SeNtinel Application Platform (SNAP) of the European Space Agency (ESA) made it possible to quantify the ocean surface affected by the phenomenon under analysis; at the same time, an algorithm was formulated within the cloud platform Google Earth Engine (GEE) which confirmed the same outputs but more quickly and allowed the implementation of an algorithm that exploits the statistical concept of value of Otsu threshold. The results obtained were subsequently compared with other results extrapolated through automatic methodologies developed by ESA, which supported a better accuracy of the procedures used in this study.