Abstract
Abstract. This Pilot Study aimed at improving the information on the state of the Indonesian marine environment that is gained from satellite data. More than 2000 historical and actual synthetic aperture radar (SAR) data from ENVISAT ASAR and Sentinel-1A/B C-SAR, respectively, were used to produce oil pollution density maps of two regions of interest (ROI) in Indonesian waters. The normalized spill number and the normalized mean polluted area were calculated, and our findings indicate that in general, the marine oil pollution in both ROI is of different origin: while ship traffic appears to be the main source in the Java Sea, oil production industry causes the highest pollution rates in the Strait of Makassar. In most cases hot spots of marine oil pollution were found in the open sea, and the largest number of oil spills in the Java Sea was found from March to May and from September to December, i.e., during the transition from the north-west monsoon to the south-east monsoon, and vice versa. This is when the overall wind and current patterns change, thereby making oil pollution detection with SAR sensors easier. In support of our SAR image analyses high-resolution numerical forward and backward tracer experiments were performed. Using the previously gained information we identify strongly affected coastal areas (with most oil pollution being driven onshore), but also sensitive parts of major ship traffic lanes (where any oil pollution is likely to be driven into marine protected areas). Our results demonstrate the feasibility of our approach, to combine numerical tracer modelling with (visual) SAR image analyses for an assessment of the marine environment in Indonesian waters, and they help in better understanding the observed seasonality.
Highlights
Indonesian territorial waters cover about three million square kilometers and are home to more than 3.000 species of fish and more than 500 species of corals
Most oil pollution was observed in an area of high oil production industry, off Balikpapan and further north-east, but of less ship traffic. These findings indicate that in general, the marine oil pollution in both IndoNACE regions of interest (ROI) is of different origin
Particles were released on the last day of the months February, April, August and October in each year into the model grid boxes in the areas of the marine protected areas (MPA) in Seribu Islands (Figure 11) and Bontang and Berau (Figure 12)
Summary
Indonesian territorial waters cover about three million square kilometers and are home to more than 3.000 species of fish and more than 500 species of corals. The Indonesian coastline is longer than 80.000 kilometers, and the Indonesian archipelago encompasses more than 17.000 islands. Major ship traffic routes, connecting the economic centers on the South China Sea (and beyond) with Europe, Africa, Australia, or the Persian Gulf, run through Indonesian waters. The marine ecosystem in Indonesia is under increasing pressure due to social and economic growth in the entire region. Parts of the so-called Coral Triangle, a six million square kilometers area in Pacific Asia, lie in Indonesian territorial waters, where the coral reef area is estimated to be 20,000 square kilometers in size (Figure 2). Along with mangrove forests and seagrass meadows on the coasts, these areas are vulnerable to pollutants
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