Developing Integrated Remote Sensing and GIS Procedures for Oil Spills Monitoring at Libyan Coast

Abdallh Eljabri 1 , Caroline Gallagher 2 1 Glasgow Caledonian University

Abstract. Remote sensing (RS) and geographic information system (GIS) might contribute significantly to an accurate reading of the slimy signatures observed through satellite images. Originally, GIS has proven to be an indispensable management instrument for resource and damage assessments, oil spill response and planning. The method to the problem of oil spill mapping includes integration of the geographical, remote sensing, oil and gas production/infrastructure data and slick signatures, detected by satellite images, in GIS. The data was collected from various sources including nautical maps, geo-databases, ground truth and remote sensing data, and the GIS allows the retrieval of key information, such as forecasting oil spill locations, revealing offshore/onshore sources, and estimating the intensity of oil pollution. Remote sensing and GIS technologies will likely improve the identification and classification of oil spills, leading to construction of the final product, an oil spill distribution map. This paper discusses the work conducted through remote sensing and GIS technologies in order to develop an Oil Spill Management System. Oil spill data, access and protection information will be placed in GIS and interfaced with a relational database for rapid access, retrieval and query. The use of remotely sensed data allows to obtain essential information about marine water pollution; especially on oil spillage. Such a method has been applied to oil spill mapping on the Libyan coast. We conclude that the combination of GIS and remote sensing RS technologies provides an ideal solution for understanding the spatial/temporal distribution of oil spills in the marine environment and is considered as the core of the oil spill monitoring system.

Keywords: Oil spill pollution, GIS, Remote sensing Data.

1. Introduction Marine oil pollution is a major risk; oil Spills did happen in the past with all their negative environmental

consequences and they will likely occur in the future . Oil spills in the sea do present currently a serious environmental problem. Regularly, unauthorised discharges occur from ships and accidents at sea result in oil spillage. For instance, in the last decade there has been a growing concern over the increasing contamination and adjacent shoreline areas by oil spills (e.g. Gulf of Mexico April 2010). It can be observed that there is a lack of information on what happens to the oil after it leaks, or how to deal properly in case of oil spills, There is however a general consensus on the fact that oil pollution is one of the riskiest pollutants when it comes to health and safety, and lead to huge economic losses, as well as provoking hazards to humans and the environment [1]. Once applied to our task, GIS is considered to be an essential geo-information technology in order to acquire, store and retrieve data and images, as well as for processing the data collected into information for researchers, environmentalists and decision-makers. The most recent statistics show that, the variety of existing risks make part of the Libyan coast liable to oil pollution activity of different intensities [5]. In fact, Libyan coastal areas are already exposed to marine pollution and to all the disasters generating from it. The frequencies of the pollution often provoke severe damages on coastal environment. In such circumstances, Remote Sensing and GIS can be very useful tools to complement the methods used in Disaster Management Mitigation of disaster of oil spills management. However, it should be observed that their achievements depend on the level of knowledge obtained about the expected frequency, character, and magnitude of hazard events in an area [2]. Remote sensing also allows the monitoring of the

2012 2nd International Conference on Environment and BioScience IPCBEE vol.44 (2012) © (2012) IACSIT Press, Singapore

DOI: 10.7763/IPCBEE. 2012. V44. 4

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event as it occurs. From the vantage point of satellite, it is possible to consider, plan for and operationally monitor the event. This paper discusses the working process for the development of Oil Spill Management System in Libyan coastal area, through the use of GIS and remote sensing technologies. Such devices are expected to provide a real time and low cost system for detecting oil spill, and monitor oil spills along the Libyan coast. Practically, the System consists of three sub-systems; the detection and monitoring, then the spatial database and finally the prediction.

2. Methodology

2.1. The Geo-information Approach An approach directed towards an improvement in oil spill detection/identification in the sea with the use

Satellite images as the main source of information has been developed. Satellite images and extracted oil spill signatures integrated into the GIS significantly improve the capabilities of an oil spill [4] downloaded by monitoring system. Moreover, the GIS, as described below, is considered to be at the core of the oil spill monitoring system, allowing integration of all available data and information and producing the final product for end users and decision makers, an oil spill distribution map.

In this paper we consider a GIS as a tool for improving oil pollution identification and classification in Satellite image. It is proposed, that GIS approach and use of geographic, remote sensing, and other additional information can provide an important aid to correctly interpreting the slick signatures, providing a framework for analysis [4]. A schematic GIS approach to oil spill mapping is depicted in figure 1.

Fig 1: Synoptic of the method of identification

2.2. Data Availability and Acquisition GIS database for coastal areas can be provided from several sources (see table 1): All datasets and geographic information have to be compiled together and placed into a generally used

geographical projection using Environmental Systems GIS software. Table 1: database for coastal areas sources

GIS database for coastal areas sources

Vector shoreline and bathymetric data

Oil/gas production infrastructure

main shipping lanes

Fishing/aquaculture areas , coastal and marine

restricted, protected and vulnerable zones

National geophysical data centers or by digitizing detailed

nautical maps, or can be extracted from global/ regional

topographic models.

Regional/local archives, atlases or corporative databases

Nautical maps.

The responsibility of the corresponding authorities 18

2.3. Geographical Information System Physical maps of Libyan coast with scale 1:50,000 have been used as a base map for the thematic layer

and registration of each processed image. Spatial and non-spatial data have been analysed by using different functions of GIS techniques, such as vectorization, rasterization, data analysis and overlaying, and modeling to yield oil spills management system as thematic layers (Map composition). However, GIS is also considered to be at the core of oil spill monitoring systems [4]. A general view of such a system is depicted in figure 2. As shown, such a system could be composed of the data integration system based on a GIS and a number of subsystems responsible for the acquisition and processing remote sensing data and images; collection of in situ measurements and contextual information. Collected remote sensing and in situ data and measurements can be further used as input to oil spill drift models.

2.4. Spill Trajectory Model The development of a simple linear trajectory model will be customized into the GIS environment. In

addition, the direction and the velocity of the winds represent essential parameters since they are known for influencing oil slicks; accordingly the actual drift forecast takes into account all combined effects.

Oil slick movement = cw (z) . Uw + ca(z) . Ua Cw is wind drift factor, Uw is wind velocity at 10 m above the water surface, ca is current drift factor,

and Ua is depth average current velocity

3. Validation of the Methodology The results allow to state that GIS provides an efficient method for storage, retrieval, analysis and

visualisation of geographic, environmental and industrial information to support oil spill monitoring and identification. Figure 2 displays a window of the GIS constructed for oil spill applications in Libyan coast. Such a GIS was created using various sources, for example maps, charts, satellite images, raster and vector digital data and textual information.

Figure 3 displays only layers related to affected and non-affected areas by oil production and transportation: lease blocks, oil shipping routes, pipelines, oil and gas fields and bearing structures. Some of these results have already been presented and published [3], [4], [6], [7]. As a particular case, mapping the results for oil slicks associated with the bottom seepage in the southwest Caspian Sea with the use of SAR and GIS is presented by [8].

Fig 2: A window of the GIS constructed for oil spill monitoring in the libyan coast ,showing: affected and none affected

areas , oil transportation routes, pipelines, oil and gas fields.

4. Conclusion and Discussion The geographic information approach presented shows that it is feasible to compile oil spill distribution

maps using satellite imagery and GIS. Oil spill maps clearly indicate those marine areas that are exposed to oil pollution. This information will likely going to be valuable and very useful both for decision-makers of

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pollution authorities as well as for experts of environmental agencies. An oil pollution distribution map is a valuable and necessary remote sensing product and is of commercial value (figure 3)

A professional GIS for the mapping and identification of oil pollution affected areas and their sources should consist of the following data sets and their respective sources in Table1 (see also figure2)

Fig. 3: Approach to Geoinformation analysis: reproduced from [8].

One of the major advantages of GIS is the ability to extract oil pollution parameters such as location, size and spill areas. Spatial and temporal information (oil spill distribution at sea and its evolution in time) allows the users to establish the major cause and source of oil spills, and then outline the risk areas.

5. References [1] Ahlang, S. (2005). Safety issues in the oil & gas industry. Energy News, No.22.Brekke, C. & Solberg, A.H.S.

(2005). Oil spill detection by satellite remote sensing, Rem. Sens. Environ., 95, 1-13.

[2] Brekke, C. & Solberg, A.H.S. (2005). Oil spill detection by satellite remote sensing, Rem. Sens. Environ., 95, 1-13.

[3] Ivanov, A.Yu., Fang, M., HE, M.-X. and Ermoshkin, I.S., 2004, An experience of using Radarsat, ERS-1/2 and Envisat SAR images for oil spill mapping in the waters of the Caspian Sea, Yellow Sea and East China Sea. In Proceedings of the Envisat and ERS Symposium, 6–10 September 2004, Salzburg, Austria (ESA SP-572), H. Lacoste and L. Ouwehand (Eds). (Noordwijk, the Netherlands: ESA Publication Division).

[4] Ivanov, A.Yu., Golubov, B.N. and Zatyagalova, V.V., 2007, On oil/gas-bearing and unloading of underground fluids in the southern part of the Caspian Sea by the use of synthetic aperture radar images [in Russian]. Earth Observation from Space, 2, pp. 62–81.

[5] KLEMAS, V., 2010. Tracking oil slicks and predicting their trajectories using remote sensors and models: case studies of the Sea Princess and Deepwater Horizon oil spills. Journal of Coastal Research, 26(5), 789–797. West Palm Beach (Florida), ISSN 0749-0208

[6] Litovchenko, K.TS., Lavrova, O.Yu., Mityagina, M.I., Ivanov, A.YU. and YURENKO, YU.I., 2007, Oil pollution in the Eastern Black Sea: monitoring from space and sub-satellite verification [in Russian]. Earth Observation from Space, 1, pp. 81–94.

[7] SHI, L., Ivanov, A.YU., HE, M.-X. and Zhao, C., 2008, Oil spill mapping in the western part of the East China Sea using synthetic aperture radar imagery. International Journal of Remote Sensing, 29, pp. 6315–6329.

[8] Zatyagalova, V.V., Ivanov, A.YU. and Golubov, B.N., 2007, Application of Envisat SAR imagery for mapping and estimation of natural oil seeps in the South Caspian Sea. In Proceedings of the Envisat Symposium-2007, 23–27 April 2007, Montreux, Switzerland (ESA SP-636), H. Lacoste and L. Ouwehand (Eds), CD-ROM, (Noordwijk, the Netherlands: ESA Publication Division).

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