Spills detection

The NOSV gives a better estimate of the detectability of marine oil pollution, independently of the local wind conditions of this particular study. These results show that higher wind speeds cause lower detectability of oil pollution, and the maximum (model) wind speed where oil spill detection in European coastal waters can be inferred. In particular, at wind speeds below 7 m s 1 oil spills are well detectable, whereas above 10 m s 1 wind speed the definite detection of marine oil pollution seems to be almost impossible. At wind speeds between 7 and 10 m s 1 the detectability of oil spills is rather low. These results can explain why less oil pollution was detected in the northern test areas during winter time. E.g., the mean wind speed in the central North Sea during winter time lies above 10 ms"1 (Figure 5), thus making it unlikely that every oil spill in that area was detectable by SAR sensors. 

Not all oil spills detected by using satellite images are necessarily illegal. In fact, we have to distinguish between spills outside special areas and spills inside special areas. Moreover, different rules apply to discharges coming from ships or offshore platforms. 

Luckily the ratio between number of images and number of spills of 1999 of 1 spill per image was not kept in the year 2000 and 2001. In fact, in the year 2000 the number of images analysed was more than twice larger (3500 images) but the number of oil spills detected increased only of 50 % (2350 spills) ... 

The results obtained analysing 1300 images for the year 2000 of the Baltic Sea are unsatisfactory. In fact only 100 oil spills were detected. This number of oil spills seems too low compared with data obtained from aerial surveillance in the framework of the Helsinki Convention (see ref. HELCOM). In particular, in the year 2000, 476 oil spills were detected by aerial surveillance (4809 flight hours). In the following years, the number of spills detected by aerial surveillance shows a positive decrease, 389 in 2001, 344 in 2002, 292 in 2003. 

Concerning the possibility to correlate the oil spills detected by satellite with spills observed by aircraft, a specific study has been developed by JRC. However, the number of matching possibilities does not have a solid scientific basis because there is too much uncertainty on the persistence and drifting of an oil spill. 

Espedal H A and Wahl T (1999) Satellite SAR oil spill detection using wind speed history information. Int J Remote Sensing 20 49-65 Fortuny J, Tarchi D, Ferraro G and Sieber A (2004) The Use of Satellite Radar Imagery in the Prestige Accident, paper submitted to Interspill 2004, 14-17 June, Trondheim, Norway... 

Bern T-I, Wahl T, Andersson T, Olsen R (1992a) Oil spill detection using satellite based SAR Experience from a field experiment. Proc First ERS-1 Symposium, Cannes, France, 4-6 Nov. 1992, p.829-834 Bern T-I, Barstow S, Moen S (1992b) Oil spill detection using satellite-based SAR. Phase 0 and 1 1992, OCN R-92071. Marine Spill Response Corporation, Washington D.C. MSRC Technical Report Series 92-004, 108 p Bravo-Zhivotovskii DM, Dolin LS, Ermakov SA, Zujkova AM, Luchinin AG, Titov VI (1984) The effect of decimeter wind wave amplification in the oil slick zone. Dokl Acad Sci USSR 276 1243-1246 (in Russian)... 

Huhnerfuss H, Alpers W, Jones WL, Lange PA, Richter K (1981) The damping of ocean surface waves by a monomolecular film measured by the wave staffs and microwave radars. J Geophys Res 86 429-438 Huhnerfuss H, Alpers W, Witte F (1989) Layers of different thickness in mineral oil spills detected by grey level textures of real aperture radar images. Int J Remote Sensing 10 1093-1099... 

Brekke C, and Solberg AHS (2005) Oil spill detection by satellite remote sensing. Remote Sensing of Environment 95 1 -13... 

Del Frate F, Petrocchi A, Lichtenegger J, and Calabresi G (2000) Neural Networks for oil spill detection using ERS-SAR data. IEEE Trans Geosci Rem Sens 38 2282-2287... 

Figure 20. Spill detection and related pollutants (the absorbance values are calculated from the dilution factor).

In the frame of alert systems, wind, waves and currents can scatter a few hours a large oil spill over a wide area within in the open sea. Moreover, while UV scanners capture the ultraviolet radiation reflected by the sea surface, false detection may occur due to the wind sheen. Both very low and very high wind speeds influence oil spill detection by radars. At high wind speed, even thick oil slicks are dispersed into the water column and oil caimot be detected at low wind speed it is not possible to distinguish between thick and thin oil sUcks false alarm or misinterpretation of SAR data can occur in the absence of accurate wind speed measurements. 

Del Frate, F. A. Petrocchi, J. Lichtenegger, G. Calabresi, Neural networks for oil spill detection using ERS-SAR data. IEEE Transactions on Geoscience and Remote Sensing 38 (5), 2282-2287 (2000). 

The employer should institute a leak and spill detection program for operations involving MDA in order to detect sources of fugitive MDA emissions. 

Leak and spill detection, (i) The employer shall implement procedures to detect leaks of MC in the work-place. In work areas where spills may occur, the employer shall make provisions to contain any spills and to safely dispose of any MC-contaminated waste materials. 

C) Implementation of work practices (such as leak and spill detection, cleanup and enclosure of containers) required by paragraph (f)(1) of this section by the applicable dates indicated in paragraph (n)(2)(iv) of this section. 

How much of the transported commodity might be released The answer to this differs at different locations along a pipeline and can be derived from pipeline flow rates, spill detection time, pipeline shutdown time, drain down volume, and other technical factors. 

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