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Mozambique Channel Mapping: Oil Spill Detection and Coral Reef Monitoring

The Mozambique Channel was identified as a high-risk area for pollution of the marine environment from ship-borne and ground sources. Approximately 30% of world’s crude oil is transported through the Channel with five thousand (5000) tanker or VLCC (very large crude carriers) voyages per year and 500 millions tons of oil products transiting through the regional waters. In recent years the traffic has intensified, including the number of vessels carrying crude oil and hazardous noxious substances (HNS) cargoes. Consequently, the risk of accidents from collisions and heavy weather conditions has also increased significantly.

The Western Indian Ocean region includes five coastal countries (Kenya, Mozambique, South Africa, Tanzania, and Somalia), one large island state (Madagascar), three small island states (Comoros, Mauritius and Seychelles), and the island territories of France in the southwest Indian Ocean (La Réunion union). Various threats to marine and coastal resources result from the growing population and expanding urbanization trends in these countries as well as economic activities in their coastal and marine economic zones. The region contains 13 major commercial ports and illegal discharges and spills originating from port activities represent additional considerable risk of pollution.

Potential damage due to accidental spills and illegal discharges from ships or ports would have disastrous consequences to the unique and ecologically vulnerable marine ecosystems of the region. This area is  contains a number of protected marine and coastal reserves including the UNESCO’s World Heritage site of Aldabra Atoll in Seychelles as well as two of the six Large Marine Ecosystems located in Africa: Agulhas and Somali Current. Extensive coral reefs are prevalent in Mozambique, Madagascar and Tanzania, so are the mangroves forest and internationally significant wildlife including marine turtles and dugong. These coastal ecosystems bear significant importance for local economy as the local population relay on these natural resources as a major source of income (e.g. tourism, aquaculture). In the event of a major spill, the entire economy of small island countries such as Comoros, Mauritius and Seychelles could be jeopardized.

Protecting the region coastal and marine environments and rich biodiversity from damage is one of the priorities of the Global Environment Facility (GEF) which plays a critical role in improving marine environmental protection around this heavily trafficked route by developing regional cooperation and strengthening technical capacity to respond to disasters, enhance maritime surveillance, navigation services, and port control. The GEF activities in the region have two main objectives: to help prevent ship-based environmental contamination (such as oil spills from groundings and illegal discharges of ballast and bilge waters) and unsustainable exploitation of marine resources (such as illegal fishing and fishing practices), and to strengthen the capacity of countries to respond to an oil spill emergency.  This includes development and installation of a pilot regional marine electronic highway- an integrated system of electronic nautical charts, continuous real-time positioning information, aids to navigation and shore-based Automatic Ship Identification System (AIS), transponders, and provision of real-time meteorological, oceanographic, and navigational information.

Collaboration with the European Space Agency

The World Bank and the European Space agency have partnered in support of GEF efforts to pilot operational regional oil spill response plan and mapping of environmentally sensitive areas. Satellite-based monitoring implemented in the Mozambique Channel represents ten years of investmants in pioneering the use of space technologies for maritime monitoring and surveillance. Currently all European waters and adjacent high seas are covered for detection of potential oil slicks. An alert is provided within 30 minutes of the satellite acquiring the image to European Union (EU) coas guards and the European Maritime Safety Agency (EMSA). This system is used in support of the aerial and vessel surveillance to ensure that they detect and communicate all significant discharges.

Western Indian Ocean is the first area outside of Europe, where such advanced monitoring tools are currently being piloted demonstrating that the state-of-the-art solutions can be quickly brought the other parts of the world to strengthen the capacity of developing countries to respond to an oil spill emergencies. In the case of Mozambique Channel, the beneficiary countries include Comoros, Kenya, Madagascar, Mauritius, Mozambique, Seychelles, South Africa, and Tanzania covering a combined coastline of 13,300 kilometers. The regional oil spill response center is planned to be hosted by the South African Maritime Safety Agency (SAMSA).

Satellite-based oil spill monitoring in the Mozambique Channel

Earth Observation data were used to support anti-pollution operations and polluter identification and to characterize oil spill occurences (frequency, time and place of occurrence). The concept of operations has three components:

  • Oil spill detection relying  on wide-swath SAR (Synthetic Aperature Radar) imagery and polluter identification with satellite Automatic Identification System (AIS) data
  • Near real time (30 min – 1hr) notification of the presence of oil spill to the national coast guard and port authorities in the participating countries 
  • Dedicated web portal with the information

Oil spill detection and polluter identification system relies on wide-swath radar imagery coupled with satellite AIS (Automatic Idendification System) data to provide reports concerning potential oils spill to the users in near real time. At the time of implementation of the project (from July to December 2011) as many as 38 oil spills were detected covering of total 17,5 millions square kilometers in 5 months and using 117 radar images from ENVISAT and Radarsat-2 satellites.


Oil spill service results (c) CLS

Figure1: The image of the catalog of satellite aquisitions and the pattern of detected pollutions. A shipwreck off the coast of Mauritius and deployed oil spill contingency. Credit: CLS

Monitoring of environmentally sensitive areas 

Protecting the region coastal and marine environments and rich biodiversity from damage is one of the priorities in the region. The evaluation of the data gaps and assessment of the quality of existing information as well as the existing measures to address threats of pollution revealed the need to develop regionally harmonized maps of environmentally sensitive areas. Preparation of the regional database on marine and coastal resources as well as methodology for evaluating ecosystem benefits is ongoing under the GEF guidance.

Various satellite were analyzed for monitoring of the environmental stress conditions. This consisted of the bi-weekly delivery of six kinds of products: hi-res and low-res sea-surface temperature, suspended sediment concentration, water transparency, chlorophyll concentration, and significant wave height. 

Sea surface temperature and chlorophil concentration in Mozambique Channel (c) CLS 

Figure2: Maps of chlorophyll concentration and sea surface temperature (SST). Credit CLS

The assessment of coral reef health and evolution included four study sites: Aldabra Atoll in the southwest Seychelles (a UNESCO World Heritage site since 1982 and an official Ramsar site since 2010), Mayotte (France), Rodrigues (Mauritius), and Tulear (Madagascar). High resolution optical data were used for coral reefs habitat maps (detailed geomorphological zonation) and change detection (spanning 2000-2011).

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Last updated: 2012-05-30

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