Oil spill assessment and coastal zone management planning for the Misratah coastline, Libya

Abstract

Knowledge of the spatial distribution of shoreline sensitivity, coastal resources and habitats vulnerable to an oil spill is crucial for effective coastal zone management. This goal is best achieved if the location of sensitive resources and the potential oil spill deposition areas are identified in advance, allowing protection priorities to be established and clean-up strategies selected to mitigate the environmental consequences of the spill. The risk of accidental oil spill in Libyan coastal waters might increase in the future, reflecting trends in (a) proposed oil exports from the Libyan coast, (b) increased marine shipping near the Libyan marine area and (c) proposed offshore oil exploration and production in western Libya. Moreover, the national coastal zone management strategy for Libyan coasts has not yet been applied. The poor coastal infrastructure, limited management facilities and the lack of oil spill monitoring and emergency plans, might increase spill impacts on coastal resources and habitats, making oil spills more complicated and increasing removal time. Therefore, a new regional oil spill management plan is developed for this thesis. A number of steps are required to build the scientific basis for the management of oil spills. Resources need to be identified and mapped, and those at most risk need identifying. The thesis builds a case study by identifying and mapping information on coastal resources, with an emphasis on coastal oil spill risk along the shoreline of the Misratah region. Three components were developed and integrated into evaluations of coastal risk from oil spills: (1) identification of biological, economic and cultural resources and their potential sensitivities to oil spills, (2) application of the Environmental Sensitivity Index (ESI) approach, and (3) oil spill simulation modelling. The outcome is the first reliable, high-resolution coastal zone strategy for the area, which can serve as a tool for shore-based management. The audit of cultural and natural resources identified areas of considerable wildlife value (for migratory birds and sea turtles), alongside sites of historic importance and local industry (fishing, saltpans). Particular features of the Libyan coast include wells on the shore close to the sea and beaches protected by offshore reefs that may break the surface. The Environmental Sensitivity Index (ESI) methodology was used to summarise potential vulnerability of sections of the coast on the basis of coastline morphology. Eleven shoreline classes were described in the study region, with vegetated low bank shores, ESI 9, as the most sensitive, and the exposed rocky shores and exposed man-made structures (ESI 1 and ESI 1 A) the least sensitive. To quantify potential oil spill pathways, the GIS-based simulation GNOME (General NOAA Operational Modeling Environment) was used in simulations of summer and winter seasonal conditions. This process identified coastal areas at higher risk of receiving spilt oil and the likely behaviour of oil slicks on the sea surface in the different seasons. The integrated oil risk assessment methodology applied in the thesis produced 43 ESI maps, covering 248 km of the Misratah coast. The shoreline areas most sensitive to oil spills are on the Eastern coast of the region. These are shores of ecological importance as coastal wetlands, turtle nesting areas and habitats for migratory birds. The risk of spilt oil reaching these high-sensitivity areas is relatively low, due to prevailing winds and currents. Approximately half of the 128 km of very high sensitivity shore was at medium risk of spills. This 128 km can be a priority for management measures, along with 12 km of high and medium sensitivity shores at high risk of oil. The majority of the shoreline faces a medium oil spill risk, especially along the North coast where potential oil spill resources are located. Overall, the thesis provides new information on both the littoral of Misratah and sources of oil, including identifying sensitive areas at most risk of pollution. This information can form the basis of coastal management for the region and communication with stakeholders. A fuller picture of the impacts of oil spilt in the region needs better monitoring infrastructure and consideration of links to the ecosystem services provided by fishing, tourism and salt production.